60th annual meeting austrian physical society 6–10 september … · 2010. 9. 6. · 8.4 fakt 54...

60th Annual Meeting Austrian Physical Society

6–10 September 2010 Salzburg, Austria

Faculty of Natural Sciences University of Salzburg

Hellbrunnerstrasse 34, 5020 Salzburg, Austria

Impressum

Herausgeber: Für die ÖPG Maurizio Musso Universität Salzburg FB Materialforschung & Physik

Hellbrunnerstr. 34 A 5020 Salzburg AUSTRIA Tel: +43-662-8044-5525 Fax: +43-662-8044-150 E-mail: [email protected]

Layout: Claudia Heissl

Druck: Offset Druckerei 5020

EHRENSCHUTZUnder the auspices of

LandshauptfrauMag. Gabi Burgstaller

Rektor der Paris Lodron Universität O.Univ.-Prof. Dr. Heinrich Schmidinger

Vize-Rektor der Paris Lodron Universität O.Univ.-Prof. Dr. Albert Duschl

Dekan der Naturwissenschaftlichen Fakultät O.Univ.-Prof. Dr. Georg Amthauer

ORGANISATIONSKOMITEE Organisation Committee

Ao.Univ.-Prof.DI Dr. Maurizio Musso Leitung und Organisation

Claudia Heissl Tagungsbüro Organisation Tagungsband

Dr. Wilhelm Heidegger EDV, Technik

DANKSAGUNG Acknowledgements

Die Organisatoren danken für die freundliche Unterstützung von The organizers wish to thank for the friendly support by

Bundesministerium für Wissenschaft und Forschung

Bundesministerium für Unterricht, Kunst, und Kultur

Land Salzburg

Stadt Salzburg

SPONSOREN / FIRMENAUSSTELLER Sponsors / Industrial Exhibtion

INHALTSVERZEICHNIS Table of Contents

1. Allgemeine Informationen / General Information 1

2. Programm / Program 63. Energietag (AKE) 74. Teilchen_at / Exhibition 135. Hauptvorträge / Plenar Talks 146. Physik in Österreich – Physics in Austria 217. Preisvorträge / Prize Lectures 278. Fachtagungen / Topical Sessions 34 8.1. ACP 34 8.2 AKU 35 8.3 AMP 41 8.4 FAKT 54 8.5 FKP-NESY 88 8.6 GEP 116 8.7 LHS 121 8.8 MBU 123 8.9 OGD 1339. Poster 159 9.1 AMP 159 9.2 FAKT 168 9.3 FKP 180 9.4 GEP 196 9.5 MBU 197 9.6 NESY 199 9.7 OGD 204

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1. Allgemeine Informationen / General information

Die aktuellen Informationen können unter http://www.events.sbg.ac.at/oepg2010abgerufen werden.

Die actual information can be downloaded from the conference website: http://www.events.sbg.ac.at/oepg2010

Tagungsort / Conference Venue

Universität Salzburg, Naturwissenschaftliche Fakultät, Hellbrunnerstr. 34, A-5020 Salzburg, Austria.

University of Salzburg, Faculty of Natural Sciences, Hellbrunnerstr. 34, A-5020 Salzburg, Austria

Das Tagungsbüro befindet sich für die Dauer der Jahrestagung in der Natur-wissenschaftlichen Fakultät beim Haupteingang.

The conference office is situated at the main entrance oft he Natural Sciences Faculty for the duration of the conference.

Die Tagungsanmeldung ist über das Formular der Website: http://www.events.sbg.ac.at/oepg2010/files/registration_form_engl_oepg_2010.pdfoder auch direkt vor Ort im Tagungsbüro möglich.

The conference registration can be done via the registration form to be downloaded from the website http://www.events.sbg.ac.at/oepg2010/files/registration_form_engl_oepg_2010.pdfor directly at the conference registration desk.

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Tagungsgebühren / Conference fees

Anmeldung und Zahlungsmodalitäten / Registration and Payment

Vor der Konferenz / Before the conference:

Banküberweisung an / Bank transfer to

UniCredit Bank Austria AG (Rainerstr. 2, A-5020 Salzburg) BLZ 12 000; Kto-Nr. 0695 3834 602; Universität Salzburg IBAN AT23 1200 0069 5383 4602, BIC BKAUATWW Referenzcode / Reference code: ÖPG 2010 ; Kostenstelle P_148500_03

Bei Tagungsrezeption: Es wird um Barzahlung ersucht. Die Anmeldung vor Ort (siehe auch Tagungsprogramm) beginnt am Mo, 6. Sept. 10-16 Uhr, am Di, 7. Sept.

Kategorie Vor 31. Juli 2010 Before 31 July 10

Nach 31 Juli 2010 After 31 July 10

ÖPG Mitglied und assoz. Mitglied

ÖPG Member and assoc. Members

EURO 60 EURO 70

ÖPG Nicht-Mitglied

Non-Member EURO 80 EURO 90

Lehrer

Teacher EURO 15 EURO 20

Bachelor/Master Student/Student

Doktorand/ PhD student

frei /free

EURO 15

frei/free

EURO 20

Tagesgebühr

Daily fee EURO 30 EURO 30

TagesgebührDoktorand

Daily fee PhD-student

EURO 10 EURO 10

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von 09:00 bis 17:00 Uhr, am Mi, 8. Sept., und Do, 9. Sept. von 8:30 bis 16:30 Uhr und am Fr, 10. Sept. von 8:30 bis 11 Uhr.

At the conference registration: You are kindly requested to pay in cash at the registration. The registration times (see also program) are as follows: Mo, 6 Sept. 10hr00 to 16hr00, Tue, 7 Sept. 8hr30 – 16hr30, We, 8 Sept and Thu, 9 Sept from 8hr30 to 16hr30 and on Fr, 10 Sept from 8hr30 to 11hr00.

Reisekostenzuschuss für studentische ÖPG-Mitglieder Travel support for student members of ÖPG:

Studentische ÖPG-Mitglieder können einen Reisekostenzuschuss mittels des im Tagungsbüro aufliegenden Formulars beantragen (Befürwortung durch Betreuer notwendig). Die Höhe der Zuschüsse richtet sich nach den zur Verfügung stehen-den Mitteln, der Zahl der Ansuchen sowie der tatsächlichen Höhe der Reisekosten.

Student members of ÖPG can apply for travel support via the form available at the registration. The signature (approval) of the applicants tutor is necessary on the form. The amount of support depends of the funds available, the number of applications and the actual travel costs.

Unterbringungsmöglichkeiten / Accommodation

Für die Stadt Salzburg können Unterkünfte beim Tourismusbüro Salzburg, Tel.+43/662/88 98 7-0, Fax+43/662/88 98 7-32, E-mail: [email protected]://www.salzburg.com/tourismus/185.htm oder http://www.salzburg.info online gesucht und gebucht werden.

For the City of Salzburg one can search / book via the Tourist Office Salzburg Tel.+43/662/88 98 7-0, Fax+43/662/88 98 7-32, E-mail: [email protected]://www.salzburg.com/tourismus/185.htm oder http://www.salzburg.info online

Hörsäle und Ausstattung / Lecture rooms and equipment

Die Hauptvorträge, die Preisvorträge sowie die „Physik in Österreich“-Vorträge finden im Audi Max (HS 401, Erdgeschoß) statt. Die Fachtagungen finden mit Ausnahme der AKE und GEP (Haus der Natur, Museumsplatz 5; Bus Nr. 1 vom Bahnhof und Bus Nr. 8 von der Naturwissenschaftl. Fakultät) im Erdgeschoß im Blauen (HS 402) und im Grünen Hörsaal (HS 403), sowie im 1. Stock in den Seminarräumen 411, 412, 414 und 415 statt.

Alle Hörsäle sind mit einem PC und einem Beamer ausgestattet, sodass die Mitnahme eines USB-Sticks genügt. Betriebssystem ist MS Windows XP mit PowerPoint als Standard-Präsentations-Software. Sollten Sie ein anderes Betriebs-

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system bzw. eine andere Präsentations-Software benötigen, so ist ein eigenes Notebook mitzubringen. Technische Unterstützung vor Ort ist möglich.

Die Erfahrung zeigt, dass es bei den Beamer-Präsentationen immer wieder zu zeitlichen Verzögerungen beim Ablauf der Sitzungen kommen kann (Inkom-patibilitäten von Soft- & Hardware, Nicht-Standard-Schriftsätze, etc.). Für einen reibungslosen Ablauf der Fachsitzungen sind die Fachausschuss-Vorsitzenden verantwortlich.

The plenary talks, the prize lectures and the session “Physics in Austria” are presented in the Audi Max (HS 401, ground floor). The topical sessions are presented in Grüner und Blauer Hörsaal (HS 402 und HS 403, ground floor) and in the lecture rooms 411, 412, 414 and 415 (first floor), with exception of the topical sessions AKE and GEP which will take place at Haus der Natur (Museumsplatz 5; reachable by bus no. 1 from the main station or bus no. 8 from the Faculty of Natural Sciences).

All lecture rooms are equipped with computer and beamer for which you only need to bring your USB-stick. Operating system is MS Windows XP with PowerPoint as standard presentation software. Should you need another operation system resp. another presentation software it is recommended to supply your own laptop. Technical assistance will be available in the lecture rooms. Experience has proved that there are always delays with preparation of lectures due to incompatibility of software, etc. The chairmen and -women of the topical sessions are responsible for the smooth operation of the session.

Posters Format: Breite max. 97 cm, Höhe max. 147 cm, bzw. A0 Format. Posters können bei Beginn der Tagung (Mo, 6. Sept. 2010) angebracht werden, und sollten möglichst bis zum Abend des 9. Sept. 2010 ausgestellt bleiben. Bei der allgemeinen Postersitzung am Di, 7. Sept. 2010, 15:30 Uhr, sollte mindestens ein Autor beim Poster anwesend sein.

Format: Width: 97 cm, Height 147 cm (A0 Format). You can fix your poster on the first of day of the conference (Mo, 6 Sept. 2010). On Tue, 7 Sept. 2010, at 15hr30 there should be at least one author presenting the poster at the general poster session.

Internet-Zugang, E-mail / Access to Internet and E-MailAllen Tagungsteilnehmern stehen während der Tagung 10 PCs mit Internet-Zugangim Trakt des Zentralen Informatikdienstes (Computerraum für Studierende; siehe Plan) in der Zeit von 10 bis 18 Uhr zur Verfügung. Für die Nutzung dieser PCs wird Username und Passwort an der Registration ausgegeben.

Zugang zum WLAN: Benutzer, die an ihrer Universität einen gültigen Account haben, kommen sich automatisch in das WLAN der Universität Salzburg einwählen.

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Bei keinem gültigen Universitätsaccount können sich die Teilnehmer bei der Registration einen Account holen (Username und Passwort).

There are 10 PCs with internet access available for all participants between 10hr00 – 18hr00 (guest computer room, 1st floor). Username and password for the participants will be provided at the registration upon request. For access to WLAN: For users with regular account at their home university(valid for Europe and Canada) the WLAN of the University of Salzburg is accessible. Users without regular account can request an account (i.e. username and password) at the registration desk.

Buffet zur Postersession / Poster session buffetDas Buffet wird am Di, 7. Sept. 2010 um 15 Uhr eröffnet parallel zur Poster-Session und um 18 Uhr geschlossen. The poster session buffet is open from 15hr00 to 18:00hr on Tuesday, 7 Sept 2010.

Übersichtsplan der Naturwissenschaftlichen Fakultät Map of Natural Sciences Faculty

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3. ENERGIETAG – Realisierung der Klimaziele ENERGY DAY – Implementing the Climate Targets

Freier Eintritt – Free entrance

Montag – Monday, 6 September 2010 / Haus der Natur

Arbeitskreis Energie - Working Group Energy (AKE)

Parallel Session AKE

Zeit Time

Vortragender Lecturer

Vortragstitel Title of Talk

14:00 - 14:10 Norbert Pillmayr (Kelag) Einleitung - Opening

14:10 - 14:50 Christian Kirchsteiger (European Commission)

2020/2050 Perspectives for Energy in the EU

14:50 - 15:30 Martin Greiner (Aarhus University)

A 100% Renewable Energy System for Europe

15:30 - 16:10 Helmuth Böck (TU Wien)

Gibt es eine Renaissance der Kernenergie?

16:10 - 16:30 Pause - Break

16:30 - 17:10 Christian Schwarz (Kelag) Generation Klimaschutz

17:10 - 17:50 Gudrun Weinwurm (TU Wien) Energie und Umwelt in der Forschung

17:50 - 18:30 Martin Thomas(OMV)

OMV Gas & Power - Adapting to the Changing Environment

18:30 - 19:00

Führung durch das Museum Haus der Natur -

Guided Tour of the Museum Haus der Natur

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AKE-1: Haus der Natur, Mo, 7. Sept, 14:10 Uhr

2020/2050 Perspectives for Energy in the EU

C. Kirchsteiger

European Commission, Directorate-General for Energy, Luxembourg

The objective of this presentation is to highlight the current and potential future roles of energy in achieving the goals of the EU 2020/2050 energy and climate policy. The relation between the achievement of these goals and the needs for further decarbonisation of energy supply is evaluated in a 2050 perspective. It is shown that the real issue is to strive for cost-effectiveness of solutions, involving both decarbonisation and efficiency measures. High shares of low-carbon electricity can be achieved in the EU by 2050 without unreasonable costs while limiting fossil fuel dependency by applying on the demand side measures related to energy efficiency, transport, co-generation, and on the supply side measures related to the use of all low carbon options, i.e. renewables, nuclear power plants, CCS and CO2 efficient fossil fuels. Renewable energy and energy efficiency measures are by no means sufficient to substitute for a phasing out of nuclear power plants. In contrary, in order to achieve a sustained and secure electricity supply under the constraints of the EU energy and climate policy goals, significant amounts of new nuclear generating capacity need to be deployed in Europe over the next few decades. An estimate of corresponding needs is given. Finally, the European Commission’s actions towards creating an EU-wide framework for a responsible use of nuclear energy are presented together with current trends on both, EU and Member State levels.


A 100% Renewable Energy System for Europe

M. Greiner1, D. Heide1, L. von Bremen2 and C. Hoffmann3

1Aarhus School of Engineering and Department for Mathematical Sciences, Aarhus University, [email protected]

2ForWind Center for Wind Energy Research, University of Oldenburg 3Corporate Research and Technology, Siemens AG

The design of a 100% renewable energy system for future Europe depends on the weather. The weather determines how much wind and solar power generation is best for Europe, how much and what kinds of storage, balancing and power transmission are needed, and how much cooperation between European countries

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is required. Simple spatio-temporal modelling, solid time-series analysis and the physics of complex networks provide quantitative answers to these important questions [1].

References [1] Heide, D., Bremen, L., Greiner, M., Hoffmann, C., Speckmann, M.,

Bofinger, S., “Seasonal optimal mix of wind and solar power in a future, highly renewable Europe”, Renewable Energy 35 (11), 2483-2489 (2010)


Gibt es eine Renaissance der Kernenergie?

H. Böck Technische Universität Wien/Atominstitut, Stadionallee 2,1020 Wien [email protected]

Am Ende der ersten Dekade des 21.Jahrhunderts zeichnet sich weltweit eine beginnende Renaissance der Kernenergie ab. Diese ist einerseits gekennzeichnet durch die Auswirkungen der Finanz– und Wirtschaftsprobleme und andererseits durch die Entwicklungen der Klimaschutzdebatte, welche eine Dekarbonisierung der Energie– und Industriestrukturen eingeleitet hat. Die Produktion und Anwendung der Elektrizität spielt in diesem Zusammenhang eine Schlüsselrolle, da auch in den nächsten Jahrzehnten mit steigendem Elektrizitätsverbrauch in den Industrie-, Schwellen- und Entwicklungsländern zu rechnen ist. Die Nutzung der Wasserkraft und der Kernenergie stellen derzeit die bedeutendste CO2 freie Erzeugung von Elektrizität mit unterschiedlichen Entwicklungen und Perspektiven dar. Österreich liegt gemeinsam mit Spanien und Luxemburg an drittletzter Stelle bei der Erreichung des Kyoto-Zieles, das bis 2020 eine CO2 Reduktion von 20% gegenüber 1990 vorschreibt. Seit etwa 10 Jahren zeichnet sich eine weltweite Renaissance der Kernenergienutzung ab, obwohl dies von vielen NGO’s und Politikern aus weltanschaulichen Gründen negiert wird. Wesentliche Aspekte dieser Renaissance sind

bedeutende Laufzeitverlängerungen bestehender Anlagen in vielen Ländern,

Revision der Nuklearpolitik (Ausstieg vom Ausstieg) in vielen europäischen Ländern und

geplante bedeutende Investitionsprogramme in vielen Ländern Europas. Ziel dieses Beitrages ist es, einen Überblick über den Stand und die zukünftige Kernenergienutzung in Europa und insbesondere in den österreichischen Nachbarstaaten zu geben. Der Fokus liegt dabei auf jenen Ländern in welchen es in den letzten Jahren bedeutende Änderungen (Ausstieg vom Ausstieg, Ausbauprogramme) in Sachen Kernenergienutzung gegeben hat. Im europäischen Kontext kann Österreich daher nicht mehr als „Insel der Nuklear-Seligen“ bezeichnet werden, sondern wird zunehmend von Nachbarstaaten

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umrundet von denen Nuklearstrom importiert wird; der Anteil in Österreich wird derzeit auf ca. 15% geschätzt. Durch den steigenden Stromimport erhöht sich der Anteil an Nuklearstrom in Österreich weiter und wir werden zu einem ökologischen Trittbrettfahrer Europas.


Generation Klimaschutz

C. Schwarz

KELAG – Kärntner Elektrizitäts-AG, Arnulfplatz 2, 9020 Klagenfurt [email protected]

Der Energiesektor steht im Spannungsfeld der Zielvorstellungen des Energie- und Klimapakets der EU, der daraus abgeleiteten landesspezifischen Gesetzgebung und einem stetig steigenden Energiebedarf. Darüber hinaus nimmt die Sensibilisierung der Bevölkerung für Klimaaspekte permanent zu. Der Vortrag widmet sich nun der Thematik, wie sich die Kelag als Landesenergieversorger und internationaler Energiekonzern diesen Heraus-forderungen stellt. Es wird ausgehend von einer kurzen Darstellung der Rahmenbedingungen die Strategie der Kelag und deren Entwicklung bzw. die darin enthaltenen Maßnahmenschwerpunkte vorgestellt. Einen wesentlichen Bestandteil zur Umsetzung der Strategie stellt die Kampagne „Generation Klimaschutz“ dar, weshalb auf diese im Besonderen eingegangen wird. Mit der Kampagne „Generation Klimaschutz“ verfolgt die Kelag das Ziel, das Bewusstsein ihrer Kunden für Klimaschutz und Energieeffizienz zu schärfen, um ihrer hohen Verantwortung nachzukommen.


Energie & Umwelt in der Forschung

G. Weinwurm1, S. Seidler2 und B. Neunteufl3

1,2Technische Universität Wien, Vizerektorat für Forschung, 1040 Wien, Karlsplatz 13, [email protected] Universität Wien, Büro für Öffentlichkeitsarbeit, 1040 Wien, Operngasse 11 Das Wachstum der Weltbevölkerung und die zunehmende Globalisierung – und dadurch auch Industrialisierung – werden zu einer Verdoppelung des Primär-energiebedarfs bis zum Jahr 2050 führen. Der vermehrte Einsatz von fossilen Ressourcen (Kohle, Öl und Gas) ist einerseits wegen der begrenzten Reserven mit

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Risiken bei der gesicherten und preisstabilen Beschaffung verbunden, andererseits mit Klima- und Umweltauswirkungen wie Erderwärmung und Luftverschmutzung. Bei der Lösung dieses Konfliktes werden traditionelle technologische Lösungs-ansätze immer stärker versagen, die auf einer Effizienzsteigerung von bekannten Energieumwandlungstechnologien und auf Methoden und Verfahren zur rascheren Erschließung von zusätzlichen (fossilen) Ressourcen beruhen. Die Betrachtung der gesamten Energiewandlungskette und der Technologie-lebenszyklen in ihrer Effizienz, ihren Kosten und ihren Umweltauswirkungen wird genauso erforderlich sein wie die stärkere Orientierung in Richtung nachhaltiger Technologien. Unter diesen Gesichtspunkten erfolgte eine Neuorientierung der Energieforschung an der Technischen Universität Wien. Der Forschungsschwerpunkt Energie und Umwelt verfolgt einen systemtechnischen und interdisziplinären Ansatz, bei dem die breiten technologischen Kompetenzen der TU Wien im Energiebereich durch interne wissenschaftliche Expertise in den Bereichen Klima, Umwelt, Wirtschaft und Ressourcen erweitert werden. Getreu dem Mission Statement der TU Wien „Technik für Menschen“ können dadurch für die bedeutenden lokalen und globalen Zukunftsfragen an Forschung, Wirtschaft und Gesellschaft genauso ganzheitliche Lösungen erarbeitet werden wie für komplexe interdisziplinäre Forschungs-aufgaben. Aufbauend auf der an der TU Wien vorhandenen Kompetenz wurden sechs wesentliche Forschungsgebiete zum Thema Energie und Umwelt identifiziert: „energieaktive Siedlungen und Infrastrukturen“, „nachhaltige und emissionsarme Mobilität“, „klimaneutrale Energieerzeugung, -speicherung und -verteilung“, „Umwelt-Monitoring und Klimaanpassung“, „effiziente Nutzung von stofflichen Ressourcen“, „nachhaltige Technologien, Produkte und Produktion“. Um die Vernetzung und den Informationsaustausch zwischen den Forschungsgruppen an der TU Wien zu erweitern, wurde das virtuelle Forschungszentrum „Energie und Umwelt“ gegründet, das unbehindert durch organisatorische Grenzen wie Institute oder Fakultäten aufgestellt, als offenes Netzwerk organisiert und in einem zentralen Managementknoten gebündelt ist. Es dient als Kommunikations- und Projektplattform für die ForscherInnen der TU Wien, um neue Ideen und Zusammenarbeiten im Rahmen von innovativen interdisziplinären Projekten zu ermöglichen und fakultätsübergreifende Lösungen zu erarbeiten. Durch diese Initiative ist eine stärkere Nutzung von Synergien zu erwarten, sowie eine erhöhte Aufmerksamkeit von Öffentlichkeit und Förder- und Auftraggebern in Bezug auf die Kompetenzen der TU Wien. Selbstverständlich und notwendig ist auch die Offenheit und Kooperations-bereitschaft nach außen. Im Rahmen des Forschungsschwerpunktes erfolgen der Ausbau und eine Verstärkung der Kooperationen mit anderen österreichischen Universitäten, sowie der Ausbau der Kooperation mit Wirtschaft und Körperschaften und eine Internationalisierung der Forschung.

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OMV Gas & Power – Adapting to the Changing Environment

M. Thomas

OMV Power International GmbH, Trabrennstrasse 6-8, 1020 Wien, [email protected]

The energy market environment is currently changing, long term growth of gas and power is expected. Key drivers for this assumption is further electrification, CO2regulations and increased liquidity of gas and power markets. Power generation in OECD Europe drives the gas demand increase. European import dependency shapes the gas infrastructure development as Europe is the largest net gas importer, domestic production is decreasing and the link between Southeastern and Caspian supply regions will increase flexibility. OMV is adapting its business portfolio based on the changing energy map. Creation of energy hubs, new development of combining CO2 capture technologies with EOR and EGR, and strengthening E&P and Gas&Power in terms of investments will change the portfolio. On top, OMV invests in gas fired and renewable power generation assets. Conversion from gas to power enables the optimization of gas and power assets in OMV’s core markets. Building up a balanced portfolio of power plants in terms of fuel and markets will create additional value to OMV and a reduction of the CO2footprint. The flexibility of gas fired power plants and renewable assets fit well together. Overview on the status quo of OMV’s power plant projects: CCPP Brazi/Romania, CCPP Samsun/Turkey, CCPP Haiming/Germany, windpower Dorobantu/Romania, Heat Recovery Plant Weitendorf/Austria.

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4. teilchen.at EXHIBITION

Ausstellungsdauer / duration of exhibition:

3 bis 20 September 2010 Mo - Fr 8:30 – 18:30

Ausstellungsort / Location: Foyer der Naturwissenschaftlichen Fakultät, Universität Salzburg

Hellbrunnerstrasse 34, A 5020 Salzburg

Freier Eintritt – free entrance

http://events.teilchen.at

Moderne Grundlagenforschung aus dem Bereich Sterne.Kerne.Teilchenmit Fokus auf österreichische Beiträge und ihre Anwendungen sind Thema der „teilchen.at“ Ausstellungen.

Subject of the exhibition “teilchen.at” is modern fundamental research around the topic Stars.Nuclei.Particles, focused on Austrian contributions and related applications.

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5. HAUPTVORTRÄGE / PLENARY TALKS

Dienstag - Tuesday 7 September 2010 / Audi Max

Plenarvorträge - Plenary Talks

Zeit Time


Vortragstitel Title of Lecture

10:30 11:30 Reinhard Kienberger (MPQ Garching)

Attosecond Physics - From generation of attosecond pulses to applications

on solids

11:30 12:30 Rupert Ursin (IQOQI Wien) Entangled photons

Öffentlicher Vortrag - Public Lecture

18:30 20:00 Rudi Grimm (IQOQI Innsbruck)

Cool und faszinierend: Quantenmaterie am absoluten Nullpunkt

Mittwoch - Wednesday 8 September 2010 / Audi Max


Zeit Time



9:00 10:00 Harald Giessen (Univ. Stuttgart)

Three-dimensional metallic metamaterials:

From simple to complex – coupling matters!

10:00 11:00 Osamu Kumagai (Sony Corporation)

Physics in Industry, 50 Years of laser innovation of laser diode

and optical storage

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Donnerstag - Thursday 9 September 2010 / Audi Max


Zeit Time



10:30 11:30 Steven T. Bramwell (University College London)

Magnetricity and magnetic monopoles in spin ice


18:30 20:00 Robert Schöfbeck (HEPHY, ÖAW)

Sterne - Kerne – Teilchen: Eine Reise von den kleinsten Teilchen bis zu den Grenzen des Weltalls auf der Suche

nach der neuen Physik

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PVH-1: Audi Max, Di, 7. Sept, 10:30 Uhr

Attosecond Physics - From Generation of Attosecond Pulses to Applications on Solids

R. Kienberger

Max-Planck-Insitut für Quantenoptik, Garching, Germany

The generation of ever shorter pulses is a key to exploring the dynamic behavior of matter on ever shorter time scales. Over the past decade novel ultrafast optical technologies have pushed the duration of laser pulses close to its natural limit, to the wave cycle, which lasts somewhat longer than one femtosecond (1 fs = 10-15 s) in the visible spectral range. Time-resolved measurements with these pulses are able to trace atomic motion in molecules and related chemical processes. However, electronic dynamics inside atoms often evolve on an attosecond (1 as = 10-18 s) timescale and require sub-femtosecond pulses for capturing them. Atoms exposed to a few oscillation cycles of intense visible or near-infrared light are able to emit a single electron and XUV photon wavepacket of sub-femtosecond duration [1,2]. Precise control of these sub-femtosecond wavepackets have been achieved by full control of the electromagnetic field in few-cycle light pulses [3]. These XUV pulses together with the few-cycle (few-femtosecond) laser pulses used for their generation have opened the way to the development of a technique for attosecond sampling of electrons ejected from atoms or molecules [4]. This is accomplished by probing electron emission with the oscillating electric field of the few-cycle laser pulse following excitation of the atom by the synchronized sub-femtosecond XUV pulse. Sampling the emission of photo electrons in this manner allows time-resolved measurement of the XUV pulse duration as well as of the laser field oscillations [5]. After the full characterization of these tools, first experiments have been carried out to measure sub-femtosecond behavior of matter. Recently, the dynamics of the photoionization process on solids has been studied [6]. Not only that attosecond metrology now enables clocking on surface dynamics, but also the individual behaviour of electrons of different type (core electrons vs. conduction band electrons) can be resolved. Here, we measured a time delay of about 100 as on the emission of the aforemention two types of electrons. The information gained in these experiments may have influence on the development of many modern technologies including semiconductor and molecular electronics, optoelectronics, information processing, photovoltaics, electrochemical reactions, electronically stimulated chemistry on surfaces and interfaces, non-adiabatic reactions, optical nano-structuring, and interference effects in spectroscopy. References [1] M. Hentschel et al., Nature 2001, 414, 501. [2] R. Kienberger et al., Science 2002, 297, 1144. [3] A. Baltuska et al., Nature 2003, 421, 611. [4] R. Kienberger et al., Nature 2004, 427, 817. [5] E. Goulielmakis et al. Science 2004, 305, 1267. [6] A. Cavalieri et al., Nature 2007, 449, 1029.

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PVH-2: Audi Max, Di, 7. Sept., 11:30 Uhr

Entangled Photons

R. Ursin

Institute for Quantum Optics and Quantum Information (IQOQI) Austrian Academy of Science, Vienna, Austria

It is an open issue whether quantum laws, originally established to describe nature at the microscopic level of atoms are also valid in the macroscopic domain on distances accessible in space. Some proposals predict that quantum entanglement is limited to certain mass and length scales or altered under specific gravitational circumstances. Testing the quantum correlations over distances achievable with systems placed in the Earth orbit or even beyond would allow to verify both, the validity of quantum physics and the preservation of entanglement over distances impossible to achieve on ground. Another area of applications is in metrology where quantum clock synchronization and quantum positioning are studied. We proposedto the European Space Agency (ESA) to perform space-to-ground quantum communication tests from the International Space Station (ISS) orbiting at a height of approximately 400 km. We present the proposed experiments in space as well as the design of a space based quantum communication payload. Additionally we will present the ongoing ESA funded R&D activities performed in a consortium consisting of partners from academia as well as from industry.

PVH-3: Audi Max, Di, 7. Sept., 18:30 Uhr

Public Lecture: Free entrance

Cool und faszinierend: Quantenmaterie am absoluten Nullpunkt

R. Grimm

Institut für Experimentalphysik, Universität Innsbruck und Institut für Quantenoptik und Quanteninformation (IQOQI), Österreichische Akademie der Wissenschaften, Innsbruck, Austria [email protected]

Richtig "heiß" geht es in der Quantenwelt gerade dann zu, wenn es extrem kalt wird. Bei Temperaturen von nur wenigen Milliardstel Graden über dem absoluten Nullpunkt zeigen kleine Atomwolken ein sehr eigentümliches Verhalten. Es entstehen Quantenkondensate, in denen sich Millionen einzelner Teilchen völlig gleich verhalten. Eine merkwürdige Zweiklassengesellschaft tritt in Erscheinung, wobei einige Atome sich besonders gesellig benehmen, andere Atome aber zu Einzelgängern werden. So bizarr dieses Verhalten auch erscheint, liefert es einen

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Schlüssel zum tieferen Verständnis von Materie sowie die Grundlage für neue Anwendungen. Vor allem aber ist es faszinierend, verblüffend und einfach cool.

PVH-4: Audi Max, Mi, 8 Sept., 09:00 Uhr

Three-Dimensional Metallic Metamaterials: From Simple to Complex – Coupling Matters!

H. Giessen

4th Physics Institute and Research Center SCOPE, University of Stuttgart, Germany

Metallic metamaterials have shown a number of fascinating properties over the last few years. A negative refractive index, negative refraction, superlenses, and optical cloaking are some of the ambitious applications where metamaterials hold great promise. We are going to present fabrication methods for the manufacturing of 3D metamaterials [1]. We are investigating their coupling properties and the resulting optical spectra. Hybridization of the electric [2] as well as the magnetic [3] resonances allows us to easily understand the complex optical properties. Lateral as well as vertical coupling can result in EIT-like phenomena [4,5,6]. These phenomena allow construction of novel localized surface plasmon resonance sensors with a figure of merit as high as five [7]. The connection between structural symmetry and their electric as well as magnetic dipole and higher-order multipole coupling will be elucidated. It turns out that stereometamaterials [8], where the spatial arrangement of the constituents is varied, reveal a highly complex rotational dispersion.

References [1] Na Liu, Hongcang Guo, Liwei Fu, Stefan Kaiser, Heinz Schweizer, and

Harald Giessen: Three-dimensional photonic metamaterials at optical frequencies, Nature Materials 7, 31 (2008).

[2] N. Liu, H. Guo, L. Fu, S. Kaiser, H. Schweizer, and H. Giessen: Plasmon Hybridization in Stacked Cut-Wire Metamaterials, Advanced Materials 19, 3628 (2007)

[3] Na Liu, Liwei Fu, Stefan Kaiser, Heinz Schweizer, and Harald Giessen: Plasmonic Building Blocks for Magnetic Molecules in Three-Dimensional Optical Metamaterials, Advanced Materials 20, 3859 (2008).

[4] Na Liu, Stefan Kaiser, and Harald Giessen: Magnetoinductive and Electroinductive Coupling in Plasmonic Metamaterial Molecules, Advanced Materials 20, 4521 (2008).

[5] Na Liu, N. Liu, L. Langguth, T. Weiss, J. Kästel, M. Fleischhauer, T. Pfau, and H. Giessen: Plasmonic EIT analog at the Drude damping limitNature Materials 8, 758 (2009).

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[6] B. Lukyanchuk, N.I. Zheludev, S.A. Maier, N.J. Halas, P. Nordlander, H. Giessen, and C.T. Chong: The Fano resonance in plasmonic nanostructures and metamaterials, Nature Materials 9 (2010), in press.

[7] Na Liu, T. Weiss, M. Mesch, L. Langguth, U. Eigenthaler, M. Hirschner, C. Sönnichsen, and H. Giessen: Planar metamaterial analog of electromagnetically induced transparency for plasmonic sensing Nano Lett. 10, 1103 (2010).

[8] Na Liu, Hui Liu, Shining Zhu, and Harald Giessen: Stereometamaterials Nature Photonics 3, 157 (2009).

PVH-5: Audi Max, Mi, 8 Sept., 10:00 Uhr

Physics in Industry, 50 Years of Laser Innovation of Laser Diode and Optical Storage

O. Kumagai

Sony Corporation Japan

Laser Diode is always in the heart of optical storage systems and a variety of other industrial applications. Innovations in Laser Diode technologies have brought optical storage evolutions from CD, to DVD and then BD in every 10 years. Reviewing the development history would tell us how physics has created a huge market and why recent innovations will predict future applications.

PVH-6: Audi Max, Do 9 Sept., 10:30 Uhr

Magnetricity and Magnetic Monopoles in Spin Ice

S. T. Bramwell

London Centre for Nanotechnology, University College London, UK

In the absence of electrical currents Maxwell's Laws imply that magnetic phenomena can be represented in terms of magnetic charge or pole density. A consequence of this is that the ends of long thin bar magnets attract each other by Coulomb's Law, as discovered by Coulomb himself in the mid 19th century. So if magnetic poles can behave like electrical charges, can they form a magnetic equivalent of electricity - "magnetricity"? The conventional answer to this question is no, because magnetic charge in materials remains essentially dipolar as opposed to being free to move

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independently as monopoles. The independent motion of magnetic monopoles is a prerequisite for magnetricity. In this talk I shall describe recent experiments that prove that some real materials do contain magnetic charge in the form of freely moving, emergent magnetic monopoles - atom sized packets of magnetic charge that may form currents analogous to electrical currents. This remarkable phenomenon occurs in a class of material called "spin ice". I will show how the conduction of magnetic charges in spin ice is equivalent to the conduction of electric charge in weak electrolytes such as water or water ice, and I will demonstrate how this analogy enabled us to quantitatively measure the elementary magnetic charge [1].

[1] Bramwell et al., Nature 461, 956 (2009).

PVH-7: Audi Max, Do, 9 Sept., 18:30 UhrPublic Lecture: Free entrance

Sterne – Kerne – Teilchen Eine Reise von den kleinsten Teilchen bis zu den Grenzen des Weltalls auf der Suche nach der neuen Physik

R. Schönbeck

Institut für Hochenergiephysik, Österreichische Akademie der Wissenschaften, Vienna, Austria

Wir begeben uns zuerst auf eine bildhafte Reise zu den riesigen kosmischen Strukturen im Weltall, welche die moderne Physik seit kurzem vor schwierige Rätsel stellt. Auf der Suche nach der Zusammensetzung des Universums müssen wir auch in die Welt der Elementarteilchen eindringen an der man sieht, wie neueste Erkenntnisse über die kosmische dunklen Materie wichtige Impulse für Experimente am großen Teilchenbeschleuniger, dem LHC am CERN in Genf, liefern. Danach sehen wir uns an, wie die Experimente der Teilchenphysiker ablaufen, welche Technik hinter den gewaltigen Anlagen steht und wie das alles mit den großen Fragen der Kosmologie zusammenhängt.

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6. PHYSIK IN ÖSTERREICH / PHYSICS IN AUSTRIA

Dienstag - Tuesday 7 September 2010 / Audi Max

Physik in Österreich - Physics in Austria

Zeit Time



Fachausschuss Oberflächen, Grenzflächen, Dünne Schichten - Scientific Committee Surfaces, Interfaces, and Thin Layers (OGD)

13:30 13:50 Peter Puschnig (MU Leoben)

Imaging molecular orbitals through photoemission spectroscopy

Fachausschuss Kern- und Teilchenphysik - Scientific Committee Nuclear and Particle Physics (FAKT)

13:50 - 14:10 Wolfgang Dungel (HEPHY ÖAW)

Victor-Franz-Hess Prize Lecture: High precision flavor physics

at the Belle experiment

Fachausschuss Forschung mit Neutronen und Synchrotronstrahlung - Scientific Committee Research with Neutrons and Synchrotron Radiation

(NESY)

14:10 - 14:30 Oskar Paris (MU Leoben) Physics of fluids in confined geometries

Fachausschuss Festkörperphysik – Scientific Committee Solid State Physics (FKP)

14:30 - 14:50 Wolfgang Parz (TU Wien)

Femto-second spectroscopy: Measuring the beat of a quantum

cascade laser

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Fachausschuss Geschichte der Physik Scientific Committee History of Physics (GEP)

14:50 - 15:10

Franz Sachslehner (Univ. Wien)

Peter Maria Schuster (Victor-Franz-Hess-

Gesellschaft)

Brigitte Strohmaier(Univ. Wien)

Historisch wertvolle physikalische Instrumente im Europäischen Zentrum für Physikgeschichte „echophysics“ in Schloss Pöllau: eine Auswahl aus den Altbeständen der Fakultät für Physik der Universität Wien

PA-OGD-1: Audi Max, Di, 7 Sept, 13:30 Uhr

Imaging Molecular Orbitals through Photoemission Spectroscopy

P. Puschnig1, S. Berkebile2, A. J. Fleming2, G. Koller2,C. Ambrosch-Draxl1, F. P. Netzer2 and M. G. Ramsey2

1Lehrstuhl für Atomistic Modelling and Design of Materials, Montanuniversität Leoben, Franz-Josef-Straße 18, 8700 Leoben, 2Institut für Physik, Karl-Franzens-Universität Graz, Universitätsplatz 5, 8010 Graz

Angle-resolved photoemission spectroscopy (ARPES) is commonly applied to study the band structure of solids by measuring the kinetic energy versus angular distribution of the photo-emitted electrons. Here we apply this experimental technique to characterize discrete orbitals of large �-conjugated molecules. By evaluating the transition matrix element of the ultra-violet photoemission process, we are able to establish a simple relation between the observed angular intensity distribution and the Fourier transform of the initial state orbital. Thus, by measuring two-dimensional photoemission intensity maps at constant initial state energy, we are able to reconstruct the real space electron distribution of individual molecular orbitals [1,2]. We apply the technique to a crystalline film of pentacene and a highly-oriented monolayer of para-sexiphenyl adsorbed on Cu(110). The data allows us to precisely determine the molecular orientation and to image the HOMO and LUMO orbitals, respectively. Given recent advances in ARPES instrumentation, we believe the demonstrated simple relation between the photoemission intensity and the

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Fourier transform of the molecular orbital can be a valuable tool for further investigation of organic molecular films and monolayers. Moreover, we anticipate that reciprocal space maps from ARPES experiments could nicely complement scanning probe techniques in continued attempts to image individual molecular wave functions [3].

References [1] P. Puschnig et al. “Reconstruction of Molecular Orbital Densities from

Photoemission Data”, Science 326, 702-706 (2009) [2] J. Ziroff et al.,“Hybridization of Organic Molecular Orbitals with Substrate

States at Interfaces: PTCDA on Silver“, Phys. Rev. Lett. 104, 233004 (2010) [3] F. Himpsel, “Angle-resolved photoemission: From reciprocal space to real

space“, J. Electron. Spectrosc. Relat. Phenom.doi:10.1016/j.elspec.2010.03.007 (2010).

PA-FAKT-2: Audi Max, Di, 7 Sept, 13:50 Uhr

Victor-Franz-Hess Prize Lecture

High Precision Flavor Physics at the Belle Experiment

W. Dungel

Institut für Hochphysik, Österr. Akademie der Wisenschaften Nikolsdorfergasse 18, A 1040 Wien [email protected]

The Belle experiment in Tsukuba, Japan, has collected a data sample of close to 1.6 billion B meson decays which allows to study differences in the decays of particles and anti-particles with high precision. This matter-antimatter asymmetry, called "CP violation", is a necessary condition for baryogenesis, the process thought to be responsible for the matter dominance in the universe. Belle's observations confirmed the theory of CP violation by M. Kobayashi and T. Maskawa, leading to their Nobelprize in Physics in 2008. In my presentation, I will summarize some of the achievements of the Belle experiment and introduce the future Belle-II upgrade. Furthermore, I will describe how I contributed to the study of CP violation through a high precision measurement of the Cabibbo-Kobayashi-Maskawa matrix element |Vcb|.

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PA-NESY-3: Audi Max, Di, 7 Sept, 14:10 Uhr

Physics of Fluids in Confined Geometry

O. Paris

Institute of Physics, University of Leoben Franz-Josef-Straße 18, 8700 Leoben Austria Email: [email protected]

Nanoporous materials with cylindrical pores of some nanometers in diameter on a highly ordered pore lattice are ideal model systems to study the behaviour of fluids in confinement. We employed small-angle neutron scattering (SANS) and synchrotron radiation based small angle X-ray scattering (SAXS) to study liquid film formation and gas-liquid phase transitions (capillary condensation) of simple fluids [1], water [2], and the self assembly of amphiphilic molecules [3]. We also investigated the interaction of the guest fluids with the host solid pore walls, which leads to a fluid pressure dependent deformation of the solid material [4]. This deformation can be monitored in-situ by following the shift of the Bragg reflections from the pore lattice and allows extracting nanomechanical properties of the material [5]. The basic physics of the adsorption induced deformation can be understood by combining fundamental principles of fluid thermodynamics with solid mechanics [5,6].

References [1] Findenegg, G.H., Jähnert, S., Müter, D., Prass J. and Paris O., “Fluid

adsorption in ordered mesoporous solids determined by in-situ small-angle X-ray scattering”, Phys. Chem. Chem. Phys. 12, 7211-7220 (2010).

[2] Erko, M., Wallacher, D., Brandt, A. and Paris, O., In-situ Small-Angle Neutron Scattering Study of Pore Filling and Pore Emptying in Ordered Mesoporous Silica, J. Appl. Cryst. 43, 1-7 (2010).

[3] Mueter, D., Shin, T., Deme, B., Fratzl, P., Paris O. and Findenegg, G.H., Surfactant self assembly in cylindrical silica nanopores, J. Phys. Chem. Lett. 1, 1442-1446 (2010).

[4] Günter, G., Prass, J., Paris, O. and Schoen, M., Novel insights into nanopore deformation caused by capillary condensation, Phys. Rev. Lett. 101, 086104 (2008).

[5] Prass, J., Müter, D., Fratzl, P. and Paris, O., Capillarity-driven deformation of ordered nanoporous silica, Appl. Phys. Lett. 95, 083121 (2009).

[6] Schoen, M., Paris, O., Günther, G., Müter, D., Prass and Fratzl, P., Lattice deformations in ordered mesoporous matrices: Experimental studies and theoretical analysis, Phys. Chem. Chem. Phys. 12 , Advance Article, DOI 10.1039/c000782j (2010).

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PA-FKP-4: Audi Max, Di, 7 Sept, 14:30 Uhr

Femto-second Spectroscopy: Measuring the Beat of a Quantum Cascade Laser

W. Parz1, R. Haddad1, T. Müller1, G. Strasser2, and K. Unterrainer1

1Institut für Photonik, Technische Universität Wien, Gusshausstraße 25-29, 1040 Wien 2Institut für Festkörperelektronik, Technische Universität Wien, Floragasse 7, 1040 Wien

The ultrafast light- matter interaction in quantum cascade lasers below and above the threshold is explored directly in the time domain with a time resolution of 10 fs. This is done by generating broadband mid-infrared pulses by phase matched difference frequency mixing in a 30 μm thick GaSe crystal. The coherent detection works up to 70 THz, employing the electro optic effect in a ZnTe crystal. This detection scheme is invariant to the strong co-emitted light fields of the QCL above threshold, and thus, allows us to measure the whole gain dynamics below and above the laser threshold [1]. Employing free space coupling to a quantum cascade laser, we are able to determine the basic static device properties, like gain and different loss mechanisms in a broad spectral range [2]. Moreover, the high phase resolution together with time gating methods lets us determine the complex valued refractive index to a high degree of precision ( n < 7.103) [3]. We also show the possibility of this method to monitor the instant temperature in the active region using the thermo- optic effect. Dynamical properties of the gain, like gain relaxation, were measured in a pump- probe configuration and electro- optic detection. Generating strong resonant pump pulses in the mid- infrared we find induced transmission with a population relaxation time of 3 ps, for a laser below threshold. Above threshold, the relaxation time for induced absorption shortens to below 1 ps. This life time shortening is a direct consequence of the stimulated emission process [4].

References [1] J. Kröll, J. Darmo, S. Dhillon, X. Marcadet, M. Calligaro, C. Sirtori,

K. Unterrainer, Nature 449, 698-701 (2007). [2] W. Parz, T. Müller, J. Darmo, T. Müller, J. Darmo, M. Austerer, G. Strasser,

L. Wilson, J. Cockburn, A. Krysa, J. Roberts, K. Unterrainer, APL 93, 091105 (2008).

[3] W. Parz, T. Müller, J. Darmo, M. Austerer, G. Strasser, L. Wilson, J. Cockburn, A. Krysa, J. Roberts, K. Unterrainer, Optics Letters 34, 208 (2009).

[4] W. Kuehn, W. Parz, P. Gaal, T. Müller, J. Darmo, M. Austerer, G. Strasser, L. Wilson, J. Cockburn, A. Krysa, J. Roberts, K. Unterrainer, APL 93, 151106 (2008).

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PA-GEP-5: Audi Max, Di, 7 Sept, 14:50 Uhr

Historisch Wertvolle Physikalische Instrumente im Europäischen Zentrum für Physikgeschichte „Echophysics“ in Schloss Pöllau: Eine Auswahl aus den Altbeständen der Fakultät für Physik der Universität Wien

F. Sachslehner1, P. Maria Schuster2 und B. Strohmaier3

1Universität Wien, Fakultät für Physik, Strudlhofgasse 4, 1090 Wien, [email protected] 2Victor-Franz-Hess-Gesellschaft, Schloss 1, 8225 Pöllau,Stmk, [email protected], 3Universität Wien, Fakultät für Physik, Währingerstr. 17, 1090 Wien, [email protected]

Einer der Museumsbereiche ist dem „Institut für Radiumforschung der Kaiserlichen Akademie der Wissenschaften“ in Wien gewidmet, das 1910 eröffnet wurde. Es war weltweit die erste Forschungseinrichtung, die der Erforschung der physikalischen Eigenschaften des Elements Radium gewidmet war. Ausgestellt sind Messgeräte der Radioaktivitätsforschung und Möbel, großteils aus der Originalausstattung dieses „Radiuminstituts“. Die Exponate sind nunmehr im Besitz der Universität Wien, die sie dem ECHoPhysics leihweise überlassen hat. Neben den Leihobjekten, die aus dem ehemaligen Radiuminstitut stammen, gibt es noch zahlreiche optische und elektrische Objekte, die seit dem Jahr 1902 dem ehemaligen II. Physikalischen Institutes der Universität Wien zuzuordnen sind. Der Anschaffungszeitraum liegt im Wesentlichen in der zweiten Hälfte des 19. Jahrhunderts und um die Wende vom 19. zum 20. Jahrhundert. Das eine oder andere Objekt stammt sogar noch aus dem Physikalischen Museum an der alten Universität Wien und ist über das Physikalische Institut der k. k. Universität in Wien-Erdberg (Christian Doppler, Andreas von Ettingshausen, Josef Stefan) in die Türkenstraße 3 im 9. Wiener Bezirk gelangt. Ab 1875 gab es dort drei Institute: Das Physikalische Institut, das Physikalische Kabinett und das neue, von Josef Loschmidt geführte Physikalisch-Chemische Institut. Viele der gezeigten Objekte stammen aus diesem Institut, insbesondere der Periode von 1891 bis 1902, als Franz S. Exner dessen Vorstand war. Durch die Neuordnung der physikalischen Institute an der Universität Wien im Jahr 1902 wurde das Physikalisch-Chemische Institut in II. Physikali-sches Institut umbe-nannt; es übernahm zu dieser Zeit auch Geräte aus dem ursprünglichen Physikalischen Institut. Hervorzuheben sind die Originalapparate von Josef Stefan.

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7. PREISVORTRÄGE / PRIZE LECTURES

Preisvorträge - Prize Lectures

Dienstag – Tuesday, 7 September 2010 / Audi Max

Christian Doppler Preis der Salzburger Landesregierung - Christian Doppler Prize of Land Salzburg

11:30 12:30 Rupert Ursin (IQOQI Wien, ÖAW) Entangled Photons

Victor Franz Hess Preis des Fachausschusses Kern- und Teilchenphysik - Victor Franz Hess Prize

of the Scientific Committee Nuclear and Particle Physics (FAKT)

13:50 14:10 Wolfgang Dungel(HEPHY, ÖAW)

High precision flavor physics at the Belle experiment

Wissenschafter des Jahres - Scientist of the Year

18:30 20:00 Rudi Grimm

(IQOQI Innsbruck, ÖAW)

Öffentlicher Vortrag - Public Lecture:Cool und faszinierend:

Quantenmaterie am absoluten Nullpunkt

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Mittwoch - Wednesday 8 September 2010 / Audi Max

Festsitzung Preisverleihung Prize award celebration session

11:20 – 12:30 Laudationes

Fritz Kohlrausch Prize, Roman Ulrich Sexl Prize,

Max Auwärter Prize, Victor Franz Hess Prize,

Anton Paar Prize,AT&S Prize, AYPT-IYPT,

Int. Physics Olympiad, Physik-Fachbereichsarbeiten

Roman Ulrich Sexl Preis/Prize

13:15 – 13:45

Gerhard Haas (Neues Gymnasium

Leoben)

Brigitte Pagana-Hammer (GRg3

Wien, Fak. Physik, Univ. Wien)

Austrian Young Physicists' Tournament (AYPT)

International Young Physicists' Tournament (IYPT)

IYPT-Aufgaben: Eine didaktische Herausforderung für den Physikunterricht

13:45 – 14:15 AYPT- IYPT Fight Demonstration, Physics Olympiad, Physik-Fachbereichsarbeiten

Fritz Kohlrausch Preis/Prize

14:15 – 14:55 Francesca Ferlaino(Univ. Innsbruck)

Few-Body Physics with Ultracold Gases: The Fascinating Case of Cesium

14:35 – 14:55 Thomas Müller (TU Wien) Carbon-Based Optoelectronics

Max Auwärter Preis/Prize

14:55 – 15:35 Stephen Berkebile(Univ. Graz)

Epitaxial Organic Films and Their Interfaces: Growth and Electronic Structure

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Donnerstag - Thursday 9 September 2010 / Grüner Hörsaal

AT&S Preis des Fachausschusses Festkörperphysik - AT&S Prize of the Scientific Committee Solid State Physics (FKP)

16:35 - 16:50 Florian Libisch (TU Wien)

Simulation of coherent, large-scale nanostructures

Anton Paar Preis des Fachausschusses Festkörperphysik - Anton Paar Prize of the Scientific Committee Solid State Physics (FKP)

17:05 - 17:20 Daniel Primetzhofer(Univ. Linz) Electronic interactions of slow ions

Abstracts Ursin, Grimm see Plenary Talks and Public Lectures p. 17

Victor Franz Hess Prize Lecture: Abstract see Physics in Austria p. 23

AT&S Prize Lecture: Abstract see Topical Session FKP-NESY p. 104

Anton Paar Prize Lecture: Abstract see Topical Session FKP-NESY p. 107

PV-1a: Audi Max, Mi, 8 Sept, 13:15 Uhr

Roman Ulrich Sexl Preisvortrag

Das AYPT

Gerhard Haas

Neues Gymnasium Leoben

Das AYPT ( Austrian Young Physicists Tournament ), veranstaltet vom Verein AYPT – Forschungsforum junger Physiker, welches alljährlich in Leoben stattfindet, dient dazu jene Schüler auszuwählen, die als Nationalteam Österreich beim entsprechenden internationalen Turnier ( IYPT), der sog. Physik- WM, vertreten sollen. Im vorliegenden Beitrag wird auf die Entwicklung des AYPT in Österreich, den Ablauf des Turniers sowie auf die Ziele dieser Veranstaltung eingegangen.

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PV-1b: Audi Max, Mi, 8 Sept, 13:30 Uhr

Roman Ulrich Sexl Preisvortrag

IYPT-Aufgaben: Eine didaktische Herausforderung für den Physikunterricht

B. Pagana-Hammer

Landstraßer Gymnasium, SSR Wien, Fakultät für Physik, Univ. Wien

Die Aufgabenstellungen, die zur Vorbereitung auf die Teilnahme am International Young Physicists‘ Tournament (IYPT) bearbeitet werden müssen, sind das Kernstück dieses Wettbewerbs. Die im Laufe des Jahres zu bearbeitenden 17 kleinen Forschungsprojekte geben den Teilnehmerinnen und Teilnehmern Gelegenheit forschend zu lernen und zu einem selbstständig erworbenen Erkenntnisgewinn zu gelangen. Die selbständige Aneignung von Wissen durch die Beschäftigung mit den IYPT- Aufgaben, den sogenannten Tasks, lässt sich auch im Regelunterricht nützen und eröffnet völlig neue fachdidaktische Perspektiven. Die Schülerinnen und Schüler gewinnen Einblick in das Wesen der Naturwissenschaften, des naturwissenschaftlichen Arbeitens und der Forschung. Dadurch wird ein Konzeptwechsel in der Einstellung zu den Naturwissenschaften vollzogen, und ein innovativer Zugang zur naturwissenschaftlichen Bildung ermöglicht. Die persönliche Erfahrung im wissenschaftlichen Arbeiten wirkt sowohl der unkritischen Akzeptanz als auch der unreflektierten Ablehnung der Naturwissenschaften, insbesondere der Physik, entgegen. Wie eigenständige Erkenntnisprozesse mit Hilfe von IYPT-Aufgaben im Physikunterricht initiiert und begleitet werden können, soll im vorliegenden Beitrag an Hand eines konkreten Beispiels skizziert werden.

PV-1c: Audi Max, Mi, 8 Sept, 13:45 Uhr

IYPT 2010 Austrian Team, 2nd place among 23 teams: Michael Scherbela, Johannes Tiefnig, Bernhard Zatloukal (Bischöfliches Gymnasium Graz), Martin Schnedlitz (Seebacher Gymnasium Graz), Philipp Heise (BRG Auhof-Linz) Team Leader: Dieter Winkler (Bischöfliches Gymnasium Graz), Angel Usunov (IYPT - Forschungsforum junger Physiker)

PV-1d: Audi Max, Mi, 8 Sept, 13:55 Uhr

International Physics Olympiad 2010 Silver Medalists: Michael Scherbela (Bischöfliches Gymnasium Graz), Andeas Theiler (HTL Weiz); Bronze Medalist: Stephan Troyer (BG/BRG Mödling Keimgasse): Honorable Mention: Philipp Heise (BRG Auhof-Linz) Advisors: Helmut Mayr (BGRG Wien-15/Schmelz, Sir Karl Popperschule/Wien-4), Engelbert Stütz (BRG Auhof-Linz)

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PV-1e: Audi Max, Mi, 8 Sept, 14:05 Uhr

Physik-Fachbereichsarbeiten Prämierte Schüler: Markus Kunesch (Akad. Gym. Wien), Andreas Hakon Kretschmer (GRG Rosasgasse), Sebastian Schnaubelt (BG/BRG Horn) Betreuer: Katrin Graf (Akad. Gym. Wien), Andrea Mayer (GRG Rosasgasse), Hans Hofbauer (BG/BRG Horn).

PV-2a: Audi Max, Mi, 8 Sept, 14:15 Uhr

Fritz Kohlrausch Prize Lecture

Few-Body Physics with Ultracold Gases: The Fascinating Case of Cesium

F. Ferlaino1, M. Berninger2, A. Zenesini2, B. Huang2, H.-C. Nägerl2 and R. Grimm2,3

1Institut für Experimentalphysik, Universität Innsbruck, 6020 Innsbruck, Austria, [email protected] für Experimentalphysik, Universität Innsbruck, 6020 Innsbruck, Austria, 3Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria

In 1970, Vitaly Efimov predicted one of the most counterintuitive phenomena in few-body physics. He found that a system of three strongly interacting particles supports an infinite series of “giant” three-body bound states, known as trimer states, with a Russian-doll-type scaling. Despite the great attention the Efimov effects has attracted in various fields, ranging from nuclear to molecular physics, its observation remained an elusive goal for 35 years. With the advent of ultracold atomic and molecular systems with tunable interaction novel possibilities of investigation opened up. Cesium is the first species that has revealed signatures of Efimov states and related few-body phenomena. I will first give an overview of our previous observations on three-body recombination [1] and atom-dimer relaxation [2]. I will then present our results on four-body systems [3] and discuss how all these observations fit together in the Efimov scenario. Finally, I will report on the progress of our current experiments, which are dedicated to a comparison of Efimov features on different Feshbach resonances and to the search of tetramer states in dimer-dimer collisions.

References [1] T. Kraemer, M. Mark, P. Waldburger, J. G. Danzl, C. Chin, B. Engeser, A. D.

Lange, K. Pilch, A. Jaakkola, H. -C. Nägerl, and R. Grimm, Nature 440, 315 (2006).

[2] S. Knoop, F. Ferlaino, M. Mark, M. Berninger, H. Schöbel, H. -C. Nägerl, and R. Grimm, Nature Phys. 5, 227 (2009).

[3] F. Ferlaino, S. Knoop, M. Berninger, W. Harm, J. P. D'Incao, H. -C. Nägerl, and R. Grimm, Phys. Rev. Lett. 102, 140401 (2009).

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PV-2b: Audi Max, Mi, 8 Sept, 14:35 Uhr

Fritz Kohlrausch Prize Lecture

Carbon-Based Optoelectronics

T. Müller

Technische Universität Wien, Institut für Photonik, Gußhausstraße 27-29 A 1040 Wien E-mail: [email protected]

Carbon-based materials exhibit extraordinary physical properties and have therefore attracted much attention from both universities and the electronics industry. In this talk I will review our research activities on the optical and optoelectronic properties of graphene and carbon nanotubes. Specifically, I will present photoconductivity studies of graphene [1], I will discuss the origin of its photoconductive behaviour [2], and present an ultrafast (>40 GHz) metal-graphene-metal photodetector [3]. We used this graphene-based photodetector to demonstrate the faithful detection of data streams at rates of 10 gigabits per second [4]. In our carbon nanotube work, we fabricated split-gate, single nanotube diodes. We then utilized the radiative electron-hole recombination of the carriers generated at the p-n junction to produce the first nanotube true light-emitting diode [5]. The efficiency of this diode was orders of magnitude higher than what had been achieved previously using ambipolar nanotube transistors, had much lower power consumption and a significantly narrower linewidth. This light emitting diode opens up the possibility of developing nanotube single-photon sources and other nanodevices.

References [1] F. Xia, T. Mueller, R. Golizadeh-Mojarad, M. Freitag, Y. Lin, J. Tsang,

V. Perebeinos, and Ph. Avouris, “Photocurrent imaging and efficient photon detection in a graphene transistor”, Nano Lett. 9, 1039 (2009)

[2] T. Mueller, F. Xia, M. Freitag, J. Tsang, and Ph. Avouris, “Role of contacts in graphene transistors: A scanning photocurrent study”, Phys. Rev. B 79,245430 (2009)

[3] F. Xia, T. Mueller, Y. Lin, A. Valdes-Garcia, and Ph. Avouris, “Ultrafast graphene photodetector”, Nature Nanotechnol. 4, 839 (2009)

[4] T. Mueller, F. Xia, and Ph. Avouris, “Graphene photodetectors for high-speed optical communications”, Nature Photon. 4, 297 (2010)

[5] T. Mueller, M. Kinoshita, M. Steiner, V. Perebeinos, A. A. Bol, D. B. Farmer, and Ph. Avouris, “Efficient narrow-band light emission from a single carbon nanotube p-n diode”, Nature Nanotechnol. 5, 27 (2009)

33

PV-3: Audi Max, Mi, 8 Sept, 14:55 Uhr

Max Auwärter Prize Lecture

Epitaxial Organic Films and Their Interfaces: Growth and Electronic Structure

S. Berkebile

Institute of Physics, Karl-Franzens University Graz, Austria

An understanding of the interfaces in molecular organic thin films is crucial to the improvement of organic electronic devices. The interactions at interfaces between different organic layers and inorganic contact and support materials are major determinants of important factors in organic thin films such as electronic level alignment between different materials, molecular orientation and geometric structure within the organic layers, and the process of crystalline film growth. A study of three rod-like organic molecules on three inorganic substrates has been conducted using a variety of measurement techniques to gain a systematic insight into these issues. Particular attention has been given to the orientation and ordering in the first few molecular layers and the consequences of the structure of these first layers upon further crystalline growth in thin films. It will be shown that with the appropriate choice of substrate and growth conditions, well-ordered and oriented monolayer and ‘single’ crystalline films of conjugated organic molecules can be grown for further controlled studies. Such films are a prerequisite for experimental band structure determination in defined crystallographic directions and the measurement of the momentum-distribution of individual molecular orbitals with angle-resolved ultraviolet photoemission spectroscopy (ARUPS). Measurements of the inter- and intramolecular dispersion in organic molecular crystals has led to the reconstruction of real-space molecular orbitals from photoemission data and can be used to study both basic and practical properties of organic molecular thin films and monolayers, such as interactions at organic/inorganic interfaces including pi-orbital – metal hybridization and the basic electronic structure in systems of limited size and low dimensions.

This work was supported by the Austrian Science Foundation FWF. We acknowledge the Helmholtz-Zentrum Berlin – Electron storage ring BESSY II for provision of synchrotron radiation at beamline TGM-4. The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement n.°226716.

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8. FACHTAGUNGEN / TOPICAL SESSIONS

8.1 ACP – Arbeitskreis Chancengleichheit Physik

Donnerstag - Thursday 9 September 2010 / HS 411

Arbeitskreis Chancengleichheit Physik - Working Group Equal Opportunities in Physics (ACP)

Parallel Session ACP

Zeit-Time VorsitzendeChairwoman Thema - Topic

9:00 - 11:00 Regina Hitzenberger (Univ. Wien)

Offene Diskussion von Themen des Arbeitskreises - Erstellung einer Agenda

für die nächsten Jahre; Open discussion on topics

of the working group - set-up of an agenda for the next years

35

8.2 AKU – Akustik


Fachausschuß Akustik - Scientific Committee Acoustics (AKU)

Parallel Session AKU

Zeit-Time Vortragender Lecturer


13:30 - 13:50 Holger Waubke (ÖAW) Randelemente Methode mit numerisch bestimmter Greenscher Funktion

13:50 - 14:10 Wolfgang Kreuzer (ÖAW)Verwendung der Randelemente

Methode zur Berechnung von Baffle-Problemen in der Akustik

14:10 - 14:30 Georg Rieckh (ÖAW) Simulation der Wirkung verschiedener Schallschutzwandtypen

14:30 - 14:50 Ferhat Kiymaz (ÖAW)

Hörprobenauswahl zur Diagnose der auditiven Wahrnehmung anhand

mathematischen und statistischen Werkzeugen

14:50 - 15:10 Michael Mihocic (ÖAW) EXPSUITE: Software Framework zur

Durchführung psychoakustischer Experimente

15:10 - 15:30 Ewald Enzinger (ÖAW) Einfluss des GSM/UMTS Adaptive

Multirate (AMR) Sprachcodecs auf Formantmessungen

36

AKU-1: HS 412, Do, 9 Sept, 13:30 Uhr

Randelemente Methode mit numerisch bestimmter Greenscher Funktion

H. Waubke1, G. Rieckh1 and W. Kreuzer1

1Institut für Schallforschung, Österreichische Akademie der Wissenschaften, Wohllebengasse 12-14, A-1040 Wien, [email protected]

Eine analytische Lösung für Wellen einen horizontal geschichteten Halbraum lässt sich im Fourier-transformierten Raum angeben. Die Fourier-Rücktransformation über die horizontalen Richtungen hat numerisch zu erfolgen. Um auch Tunnel und Einschnitte behandeln zu können, soll mittels der Fourier-Transformation die Greensche Funktion ermittelt werden. Diese Funktion ist das Fundament der Randelemente Methode. Liegen Auswertepunkt und Punkt der Test-Belastung aufeinander, so wird die Funktion singulär und ist mithin schlecht numerisch zu behandeln. Dieses Problem kann jedoch umgangen werden, wenn die Integration über das Randelement vor der Fourier-Rücktransformation ausgeführt wird. In diesem Fall verbleibt ein einfaches Integral über eine reguläre Funktion übrig, die gegenüber der sonst notwendigen Fourier-Rücktransformation noch mittels einer sinc Funktion abgeschwächt wird, wenn man gegen unendlich geht. Mit diesem Ansatz ist es möglich, die direkte Randelemente Methode in Verbindung mit der numerisch bestimmten Greenschen Funktion zu verwenden. Darüber hinaus kann man die Randelemente Methode im einfach transformierten Raum ansetzen, sofern der Tunnel oder Einschnitt gerade ist. Anstelle eines dreidimensionalen Problems wird eine Folge von unabhängigen zweidimensionalen Querschnittsmodellen für jede Wellenzahl generiert. Dieses Vorgehen wird in der Literatur auch als 2.5D Verfahren bezeichnet [1].

Literatur [1] Tang, Z., Liu, Q. H., “The 2.5D FDTD and Fourier PSTD methods and

applications”, Microwave and Optical Technology Letters 36 (6), 430-436 (2003)

AKU-2: HS 412, Do, 9 Sept, 13:50 Uhr

Verwendung der Randelemente Methode zur Berechnung von Baffle-Problemen in der Akustik

Z.-S. Chen1 , W. Kreuzer1, H. Waubke1 und A. J. Svobodnik2

1Österreichische Akademie der Wissenschaften, Institut für Schallforschung, Wohllebengasse 12-14, A-1040 Wien; E-Mail: [email protected] International, Wien

37

Um zum Beispiel das Abstrahlverhaltens eines Hochfrequenzlautsprechers (Tweeter) zu simulieren, ist es möglich, den Lautsprecherkasten, der im Vergleich zum Tweeter sehr groß ist, als schallhart reflektierende Platte (Baffle), in der der Tweeter eingebaut ist, zu modellieren. Die Schallabstrahlung kann dann mit Hilfe der Randelemente Methode (BEM) numerische berechnet werden. Um die Berechnungen effizient durchführen zu können, wird der Raum in drei Sub-Räume zerlegt. Einen Halbraum 2 vor dem Baffle, einen Halbraum 3 dahinter und einen geschlossenen Raum 1 um das abstrahlende Objekt herum. Durch die Verwendung der Halbräume muss der Baffle nur in 1 diskretisiert werden, außerhalb wird er durch eine Randbedingung im Halbraums definiert. Es ist bekannt, dass die numerische Lösung eines akustischen Aussenraum-problems für gewisse kritische Frequenzen eine nicht eindeutig ist. Um dennoch eine eindeutige Lösung zu garantieren, wird die Randelemente Methode mit einer Burton Miller Formulierung verwendet.

AKU-3: HS 412, Do, 9 Sept, 14:10 Uhr

Simulation der Wirkung verschiedener Schallschutzwandtypen

G. Rieckh1, H. Waubke1, W. Kreuzer1 and Z. Chen1

1Institut für Schallforschung, Österreichische Akademie der Wissenschaften, Wohllebengasse 12-14, A-1040 Wien, [email protected]

Mit zunehmendem Verkehr und strengeren Schallschutzbestimmungen ist es zunehmend wichtig die akustische Wirkung von Schallschutzwänden nicht nur durch eine Steigerung von deren Höhen zu verbessern, sondern auch verschiedene Formen und absorbierende Materialien zu studieren. Zu diesem Zweck wurde eine Studie durchgeführt, bei der verschieden Typen von Schallschutzwänden in einer Simulation miteinander verglichen wurden. Die Simulation beruht auf einer zweidimensionalen Formulierung der Randelementemethode [1]. Sie berücksichtigt sowohl Form und Absorptionsvermögen der Schallschutzwand, als auch Effekte, die auf die das umliegende Gasland zurückzuführen sind. Von speziellem Interesse ist die für die Randelementemethode nötige Green’sche Funktion für den Halbraum mit Impedanzrandbedingungen.

Literatur [1] Waubke, H., Chen, Z., Kreuzer, W., “Auralization of noise recordings behind a

simulated noise barrier”, Fortschritte in der Akustik, Proceedings of the NAG/DAGA09, Rotterdam, p.637-640 (2009).

38

AKU-4: HS 412, Do, 9 Sept, 14:30 Uhr

Hörprobenauswahl zur Diagnose der auditiven Wahrnehmung anhand mathematischen und statistischen Werkzeugen

F. Kiymaz

Institut für Schallforschung der Österreichischen Akademie der Wissenschaften, Wohllebengasse 12-14, 1040 Wien, Österreich, E-mail: [email protected]

Um eine Aussage über „Lästigkeit“ von Lärm machen zu können, muss man die psychoakustischen Faktoren von Lärm mit in die Aussage einbeziehen. Um die Wirksamkeit von Schallreduzierungsmaßnahmen fest zu stellen, wurde das Institut für Schallforschung im Rahmen eines Projektes mit Erstellung und Durchführung von akustischen Wahrnehmungstests beauftragt. In einer Vorsynthese wurden aus den an uns gelieferten Messdaten, Signale der Schallereignisse rekonstruiert, und deren Schallattribute mit dem hausinternen Softwaretool S_Tools-STx errechnet. Aus den bearbeiteten Ausgangsdaten, (über 10.000 voneinander unterschiedliche Schallereignisse) wurden einige wenige, aussagekräftige ausgewählt. Sie werden in Form von psycho-akustischen Wahrnehmungstest an Testpersonen ausgewertet. Eine große Anzahl an Ausgangsdaten erforderte die Auswahl der Testsequenzen unter Verwendung von mathematischen und statistischen Werkzeugen, wie Gruppierungsverfahren, Mittelwertbildung und Approximationsverfahren an Schallattributen, die nach einer der Vorgängerprojekte [1] des Instituts für Schallforschung, für das Störempfinden des menschlichen Gehörs als relevant gekennzeichnet waren. Für die ausgewählten Testsequenzen werden an 20 normal hörenden Testpersonen unterschiedlicher Altersgruppen psychoakustische Wahrnehmungstests durchgeführt. Anhand der Auswertung der Tests werden wir ggf. eine Änderung in Störempfinden des Menschen bei variierenden Schallreduzierungsmaßnahmen feststellen. Dadurch können wir die Grundfrage „Welche Schallschutzmaßnahmen wirken bei den gegebenen Randbedingungen besser als andere“ beantworten.

References [1] Deutsch, Werner A., “Automatische Lärmbewertung von Zugsvorbeifahrten”, DAGA 2007.

39

AKU-5: HS 412, Do, 9 Sept, 14:50 Uhr

Expsuite: Software Framework zur Durchführung psychoakustischer Experimente

M. Mihocic, P. Majdak und B. Laback

Institut für Schallforschung Wien, Österreichische Akademie der Wissenschaften, [email protected]

Am Institut für Schallforschung werden seit 2003 psychoakustische Experimente mit akustischer und elektrischer Stimulation (Cochleaimplantate) durchgeführt. Vier Testplätze dienen der Durchführung psychoakustischer Studien und akustischer Messungen: Zwei doppelwandige Schallkammern der Type IAC-1202A, die für psychoakustische Tests mit Kopfhörern sowie Sprach- und Audioaufnahmen verwendet werden. Die Bedienung erfolgt mit je einem Computer, wobei 2-Kanal-Audio mit Abtastraten von 192 kHz zur Verfügung steht. Ein reflexionsarmer Raum in der Größe 6 x 6 x 3 m steht für akustische Tests im Quasi-Freifeld zur Verfügung. Der Raum unterstützt 24 bidirektionale, mit einem Computer verbundene, Audio-Kanäle sowie Audio- und Videoüberwachung und wird für Projekte wie Messung der Außenohrübertragungsfunktionen, Schallquellenlokalisationstests und akustische Holografie verwendet. Ein räumlich abgegrenzter Testplatz für Experimente mit Cochleaimplantat-Trägern bietet die Möglichkeit der direkten bilateralen elektrischen Stimulation mittels computergenerierter Signale. Für die Ansteuerung der Hardware wird ExpSuite als Software-Lösung verwendet. ExpSuite besteht aus einem Framework und den darauf basierenden Applikationen. Dabei profitiert sie von der „Rapid Application Development”-Umgebung in Visual Basic, die eine schnelle Entwicklung der Experimente ermöglicht. Durch den modularen Aufbau kann der Applikationsprogrammierer das Verhalten der Applikationen selbst definieren: zum Beispiel die Generierung einer Tabelle mit Testparametern und Ergebnissen (Item list), die Erzeugung und das Abspielen der Stimuli, den Ablauf des Experiments oder die Auswertung der Ergebnisse. Das Framework selbst unterstützt prozedurelle Eigenschaften wie zeitliche Struktur (z.B. adaptive und ineinander verschachtelte Abläufe), Parametrierung der einzelnen experimentellen Schritte, technische Anforderungen wie Steuerung über Joypad, Maus und Tastatur oder Verwendung von Touchscreen, Drehteller und Positions-Tracking-Systemen. Damit kann sich der Applikationsprogrammierer auf die Entwicklung des experimentellen Designs konzentrieren. Die auf der Item list basierende Oberfläche hat sich seit Jahren bewährt und wird ständig weiter entwickelt. Mit der direkten Anbindung an Matlab steht den ExpSuite-Applikationen eine Vielfalt von Matlab-internen Funktionen zur Verfügung, die auch zur direkten Auswertung der Ergebnisse verwendet werden können. Die Ausgabe der in vektororientierter Form in Matlab erzeugten Stimuli kann über herkömmliche akustische Audiogeräte oder als elektrische Stimulation über ein Cochleaimplantat-Interface erfolgen. Das Programm Pure Data (pd) übernimmt die akustische Signalverarbeitung in Echtzeit (z.B. komplexe Filterung und Signalgenerierung), die Ausgabe der Stimulationsdateien, sowie die simultane Aufnahme und Wiedergabe mehrerer Audiokanäle. Die elektrische Stimulation zur

40

Durchführung von Experimenten mit Cochleaimplantat-Trägern erfolgt über die Research Interface Boxen (RIBs), die eine binaural synchronisierte Stimulation der Med-El Prozessoren unterstützen. ExpSuite wird am Institut für Schallforschung entwickelt und gepflegt. Sie ist unter der European Union Public License (EUPL) lizenziert und steht unter http://expsuite.sourceforge.net allen interessierten zur Verfügung.

AKU-6: HS 412, Do, 9 Sept, 15:10 Uhr

Einfluss des GSM/UMTS Adaptive Multirate (AMR) Sprachcodecs auf Formantmessungen

E. Enzinger

Institut für Schallforschung, Österr. Akademie der Wissenschaften, [email protected]

Der bei GSM und UMTS zur Sprachübertragung verwendete Adaptive Multirate (AMR) Codec sieht acht Qualitätsstufen mit unterschiedlichen Bitraten vor. Während eines Gesprächs wird auf Basis der Kanalübertragungsqualität die optimale Stufe ausgewählt. Um Unterschiede bei durch auf LPC basierenden automatischen Trackern ermittelten Formantspuren zu untersuchen, wurden Studioaufnahmen mit den verschiedenen Codecstufen en- und dekodiert und anschließend Formantfrequenzen in Vokalen extrahiert. Dies hat besondere Relevanz für forensische Sprechervergleiche auf Basis von Formanten, wenn die Vergleichsaufnahmen von Gesprächen über Mobiltelefone stammen.

41

8.3 AMP – Atome, Moleküle, Quantenphysik und Plasmen /


Fachausschuss Atome, Moleküle, Quantenphysik, und Plasmen Scientific Committee Atoms, Molecules, Quantum Optics,

and Plasmas (AMP)

Parallel Session AMP

Zeit-Time Vortragender - Lecturer Vortragstitel - Talk Title

09:00 - 09:30 Gregor Weihs (Univ. Innsbruck) Three slits rule out multi-order interference

09:30 - 09:45 Marcus Huber (Univ. Wien)

Detection and classification of genuine multipartite entanglement in high-

dimensional mixed states

09:45 - 10:00 Christoph Uiberacker (MU Leoben)

Resonant population transfer in N-level systems by arbitrary pulses

10:00 - 10:30 Beatrix Hiesmayr (Univ. Wien)

Testing foundations of quantum mechanics in particle physics

11:00 11:30 Pause - Coffee Break

42


Fachausschuss Atome, Moleküle, Quantenphysik, und Plasmen Scientific Committee Atoms, Molecules, Quantum Optics, and

Plasmas (AMP)

Parallel Session AMP


13:30 - 14:00 Martin Ratschek (TU Graz)

Electron spin resonance in doped helium nanodroplets as tool to study magnetic

properties and spin dynamics

14:00 - 14:15 M. Ellmeier (TU Graz)

Contrast measurements of CPT resonances formed on the 87Rb D1 and D2 line

14:15 - 14:30 T. Gruber (TU Graz)

Ab initio spin densities of small alkali-metal doped helium droplets

14:30 - 14:45 Peter Cristofolini (Univ. Innsbruck)

Towards the generation of entangled photon pairs in microcavities

14:45 - 15:00 Florian Lackner (TU Graz)

Photoionization of Rb atoms on He nanodroplets

15:00 - 15:15 Elisabeth Schwarz(TU Wien)

Plasma generation by combinationof two laser wavelengths

15:15 - 15:30 Christoph Spengler(Univ. Wien)

A composite parameterization of unitary groups, density matrices and subspaces

43

AMP-1 HS 414, Do, 9 Sept. 2010, 09:00 Uhr

Three Slits Rule Out Multi-Order Interference

G. Weihs1,2, U. Sinha2, I. Söllner1, C. Couteau3, T. Jennewein2 and R. Laflamme2,4

1Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria, [email protected] for Quantum Computing and Dept. of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo ON N2L3G1, Canada 3Laboratoire de Nanotechnologie et d’Instrumentation Optique, Université de Technologie de Troyes, 12 rue Marie Curie, 10 000 Troyes, France 4Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo N2L2Y5, Canada

In Ref. [1] Sorkin investigated the possibility that quantum mechanics might be formulated as a generalized measure theory. Born's rule that quantum mechanical probabilities are absolute squares of complex amplitudes results in the interference of possible evolutions, just like in the interference of classical waves. Quantum mechanical interference violates the sum rule that probabilities of mutually exclusive events can be added. One can imagine a yet more general theory by assuming that it violates the next higher sum rule about the additivity of probabilities of three mutually exclusive possibilities. Standard quantum mechanics does obey this second sum rule and so does any classical wave theory. In other words, interference only occurs from all possible pairwise combinations of possibilities. A violation of that second sum rule would mean that there is higher order interference and that Born’s rule would have to be modified. This would have dramatic implications, most likely resulting in a nonlinear theory. It has further been shown that a modification of Born’s rule would allow computation that is more powerful than quantum computation, as well as perfect distinction of non-orthogonal quantum states. The latter would render quantum key distribution as we know it impossible. We experimentally tested the validity of the second sum rule by measuring the interference patterns produced by three slits and all the possible combinations of these slits being open or closed [2]. We use either attenuated laser light or a heralded single photon source combined with single photon counting to confirm the particle character of the measured light. Within our experimental accuracy and Born's rule is vindicated and the second sum rule appears to be obeyed [3].

References [1] R. D. Sorkin, Quantum Mechanics as Quantum Measure Theory, Mod. Phys.

Lett. A 9, 3119 (1994). [2] U. Sinha, C. Couteau, Z. Medendorp, I. Söllner, R. Laflamme, R. Sorkin, and

G. Weihs, Testing Born's Rule in Quantum Mechanics with a Triple Slit Experiment in Foundations of Probability and Physics - 5, Accardi, L.; Adenier, G.; Fuchs, C.; Jaeger, G.; Khrennikov, A.; Larsson, J. & Stenholm, S. (ed.), AIPConference Proceedings 1101, 200-207 (2009).

44

AMP-2 HS 414, Do, 9 Sept. 2010, 09:30 Uhr

Detection and Classification of Genuine Multipartite Entanglement in High-Dimensional Mixed States

M. Huber1, Andreas Gabriel2 and Beatrix Hiesmayr3

1University of Vienna, Boltzmanngasse 5, A1090 Vienna, [email protected] of Vienna, Boltzmanngasse 5, A1090 Vienna 3University of Vienna, Boltzmanngasse 5, A1090 Vienna

We present a general framework to identify genuinely multipartite entangled mixed quantum states in arbitrary-dimensional systems and show on exemplary cases that the constructed criteria are stronger than previously known ones. Our criteria are simple inequalities involving matrix elements of the given quantum state and detect genuine multi-partite entanglement that had not been identified so far. They are experimentally accessible without quantum state tomography and are easily computable as no optimization or eigenvalue evaluation is needed. We also provide an optimal way for constructing the observables needed to identify the separability. Also we show that with such inequalities it is possible to distinguish certain classes of genuinely multipartite entangled states, e.g. the GHZ and W class. Furthermore these criteria prove to be versatile tools for detecting separability with respect to different partitions of multipartite states and provide novel ways of deriving lower bounds on concurrence based entanglement measures. In the end we show how with the help of such a framework, one can go further and not only identify genuine multipartite entanglement, which is constituted by non-2-separability, but generalize it to achieve criteria for non-k-separability in arbitrary dimensional multipartite states.

References [1] M. Huber, F.Mintert, A. Gabriel and B.C. Hiesmayr, „Detection of High-

Dimensional Genuine Multipartite Entanglement of Mixed States“, Phys. Rev. Lett. 104, 210501 (2010)

[2] A. Gabriel, B.C. Hiesmayr and M, Huber, „Criterion for k-separability in mixed multipartite systems“, arXiv/quant-ph: 1002.2953

45

AMP-3 HS 414, Do, 9 Sept. 2010, 09:45 Uhr

Resonant Population Transfer in N-Level Systems by Arbitrary Pulses

C. Uiberacker1 and W. Jakubetz2

1Montanuniversität Leoben, Inst. f. Physik; [email protected]ät Wien, Inst. f. theoretische Chemie

N-level models are used in a variety of fields like biological and chemical systems (e.g. isomerization reactions [1]) but also quantum computing, quantum optics or spintronics. Furthermore in recent years strong short laser pulses became available [2]. Various control strategies [3,4] have been explored in order to steer population to a chosen level in reactions. The resulting pulse fields are usually complicated and hard to interpret, which favours an analytic approach providing simple rules [5]. By assuming the experimental pulse to have finite support in time and interpreting the duration as one period of a periodic signal we use Floquet theory to analyse the propagator. We find that the criterion on the Floquet eigenvalues for full population transfer given by Holthaus [6] for adiabatic pulses can be generalized to arbitrary pulses. However it turns out that this criterion is only necessary and the eigenvectors are needed to provide a sufficient criterion.

References [1] C.Uiberacker and W.Jakubetz, “Molecular isomerization induced by

ultrashort infrared pulses. I. Few-cycle to sub-one-cycle gaussian pulses and the role of the carrier-envelope phase“, J.Chem.Phys. 120,11532 (2004), ibid., “Molecular isomerization induced by ultrashort infrared pulses. II. Pump-dump isomerization using pairs of time-delayed half-cycle pulses“, J.Chem.Phys. 120, 11540 (2004)

[2] T. Brabec and F. Krausz, “Intense few-cycle laser fields: Frontiers of nonlinear optics”, Rev. Mod. Phys. 72, 545 (2000)

[3] H. Rabitz, R. de Vivie-Riedle, M. Motzkus, K. Kompa, “Whither the Future of Controlling Quantum Phenomena?”, Science 288, 824 (2000)

[4] M. Seidl, M. Etinski, C. Uiberacker and W. Jakubetz, “Pulse-train control of branching processes: Elimination of background and intruder state population”, J. Chem. Phys. 129, 234305 (2008)

[5] C.Uiberacker and W. Jakubetz, “Strong-field dipole resonance: Limiting analytical cases”, Phys. Rev. A 80, 063406 (2009)

[6] M. Holthaus, “Pulse-Shape-Controlled Tunneling in a Laser Field”, Phys. Rev. Lett. 69, 1596 (1992)

46

AMP-4 HS 414, Do, 9 Sept. 2010, 10:00 Uhr

Testing foundations of Quantum Mechanics in Particle Physics

T. Adaktylos1, A. Gabriel1, B.C. Hiesmayr12, F. Hipp1, M. Huber1, G. Krizek1,S. Radic1, H. Schimpf1, Ch. Spengler1 and H. Waldner1

1University of Vienna, Faculty of Physics, Botzmanngasse 5, A-1090 Vienna 2 University of Sofia, Faculty of Physics, Blvd. James Bourchier 5, 1164 Sofia, Bulgaria

Particle physics has become an interesting testing ground for questions of foundations of quantum mechanics. Entangled massive meson-antimeson systems are specially suitable as they offer a unique laboratory to test various aspects of particle physics (CP violation, CPT violation,...) as well to test foundations of quantum mechanics, e.g. Bell inequalities [1, 2, 3, 4], decoherence effects [5, 6], quantum marking and erasure concepts [7, 8], Bohr's complementary relation [9, 10]. The main aim of this talk is to show that these systems not consisting of ordinary matter and light provide novel insights into quantum theory. Particularly, we show that a certain Bell inequality is related to the observed tiny difference between matter and antimatter [3, 4], the so called CP violation explored in particle physics. Herewith two different powerful concepts in physics, entanglement or its manifestation and symmetry, become related. Then we show a Bell inequality sensitive to the quantum number strangeness [3], which is not violated for the maximally entangled spin singlet state, but surprisingly for a non-maximally entangled state [1]. This opens for the first time the possibility of a direct experimental. We will shortly discuss the status quo of the realization [11] with the upgraded KLOE detector (DAPHNE machine, Italy). In summary, understanding the nature of entanglement and its manifestation needs also studies of entanglement at different energy scales and as recent works show there are still many open questions concerning entanglement, e.g. about high dimensional genuine multipartite entanglement [12] or of relativistic entanglement of massive spin 1/2 particles [13].

References [1] B.C. Hiesmayr: Nonlocality and entanglement in a strange system.European

Physical Journal C, Vol. 5073-79 (2007). [2] B.C. Hiesmayr: A generalized Bell inequality and decoherence for the K0

anti-K0 system. Found. of Phys. Lett. 14, 231 (2001). [3] R.A. Bertlmann and B.C. Hiesmayr: Bell inequalities for entangled kaons

and their unitary time evolution. Phys. Rev. A 63, 062112 (2001). [4] R.A. Bertlmann, W. Grimus and B.C. Hiesmayr: Bell inequality and CP

violation in the neutral kaon system. Phys. Lett. A 289, 21 (2001). [5] R.A. Bertlmann, K. Durstberger and B.C. Hiesmayr: Decoherence of

entangled kaons and its connection to entanglement measures.Phys. Rev. A 68, 012111 (2003).

47

[6] R.A. Bertlmann, W. Grimus and B.C. Hiesmayr: Quantum mechanics, Furry's hypothesis and a measure of decoherence. Phys. Rev. D 60, 114032 (1999).

[7] A. Bramon, G. Garbarino and B.C. Hiesmayr: Quantum marking and quantum erasure for neutral kaons. Phys. Rev. Lett. 92,020405 (2004)

[8] A. Bramon, G. Garbarino and B.C. Hiesmayr.: Active and pas- sive quantum eraser for neutral kaons. Phys. Rev. A 69, 062111 (2004).

[9] B.C. Hiesmayr and M. Huber: Bohr's complementarity relation and the violation of the CP symmetry in high energy physics. Physics Letters A, 372 (20), 3608 (2008).

[10] A. Bramon, G. Garbarino and B.C. Hiesmayr.: Quantitative complementarity in two-path interferometry, Phys. Rev. A 69, 022112 (2004).

[11] G. Amelino-Camelia et.al: Physics with the KLOE-2 experiment at the upgraded DAPHNE. Accepted by Physical Journal C or arXiv:1003.3868.

[12] M. Huber, F. Mintert, A. Gabriel and B.C. Hiesmayr. Detection of high-dimensional qenuine multi-partite entanglement of mixed state. Phys. Rev. Lett. 104, 210501 (2010).

[13] N. Friis, R.A. Bertlmann, M. Huber, B.C. Hiesmayr. Relativistic entanglement of two massive particles. Phys. Rev. A81, 042114 (2010)

AMP-5 HS 414, Do, 9 Sept. 2010, 13:30 Uhr

Electron Spin Resonance in Doped Helium Nanodroplets as Tool to Study Magnetic Properties and Spin Dynamics

M. Ratschek1, M. Koch1,*, J. Poms1, A. Volk1, C. Callegari1,2, and W. E. Ernst1

1Institute of Experimental Physics, TU Graz, Petersgase 16, 8010 Graz, Austria 2 Sincrotrone Trieste, Strada Statale 14 – km 163.5, 34149 Basovizza, Trieste, Italy *Corresponding author: [email protected]

Superfluid helium (He) nanodroplets provide a versatile substrate to isolate and cool (0.38 K) single atoms and molecules and, if desired, assemble weakly bound complexes. Electron spin resonance (ESR) is a versatile probe of the electronic environment in radicals and, via spin tags, also in ESR-silent species. We have recently achieved ESR of single alkali-metal atoms isolated on He nanodroplets [1,2,3]. The influence of the droplet on the alkali-metal valence-electron wave function is directly noticeable as a shift of the ESR transitions with respect to that of free atoms. This perturbation depends on the size of the droplets and can be modeled with an increase of the hyperfine constant, that is, an increase of the Fermi contact interaction. After a careful characterization of the Rb-He-droplet system the method is currently being developed into a more universal diagnostic tool to study magnetic properties and spin dynamics. We believe that ESR-silent species located inside the droplet can be investigated by utilizing the surface Rb atom

48

as spin label, and the droplet size will be a convenient handle to control the distance between the two. We are also extending our method to study magnetically active materials of technological importance, such as Cr, Cu, and small clusters thereof.

References [1] Koch, M., Auböck, G., Callegari, C., and Ernst, W.E., “Coherent Spin

Manipulation and ESR on Superfluid Helium Nanodroplets”, Phys. Rev. Lett. 103(3), 035302–1–4(2009)

[2] Koch, M., Lanzersdorfer, J., Callegari, C., Muenter, J.S., and Ernst, W.E., “Molecular Beam Magnetic Resonance in Doped Helium Nanodroplets. A Setup for Optically Detected ESR/NMR in the Presence of Unresolved Zeeman Splittings.”, JPC A 113, 13347 (2009)

[3] Koch, M., Callegari, C., and Ernst, W.E., “Alkali-metal electron spin density shift induced by a helium nanodroplet”, Mol. Phys. 108, 1008 (2010)

AMP-6 HS 414, Do, 9 Sept. 2010, 14:00 Uhr

Contrast Measurements of CPT resonances Formed on the 87Rb D1 and D2 Line

M. Ellmeier1, R. Lammegger1 and L. Windholz1

1Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, 8010 Graz, [email protected]

We present investigations on contrast measurements of Coherent Population Trapping (CPT) resonances used to improve the noise performance of a new compact Coupled Dark State Magnetometer (CDSM). CPT can be understood as a quantum interference effect, which occurs in an atomic three level excitation system in the simplest case. The CPT resonances - representing so called dark states - can obtain line widths of about 30 Hz (about seven orders of magnitude smaller than the width of the optical transition), therefore this phenomenon can be used for precision measurements. In our experiment several three level excitation systems are established via a modulated vertical-cavity surface-emitting laser within the hyperfine structure of the 87Rb D1 and D2 lines. In our setup the contrast of the CPT resonances for the excitation of the D1 and D2 line is determined by an indirect contrast measurement method well-suited for small CPT resonance amplitudes with low signal-to-noise ratio.

We report an increase of the contrast for the excitation of the D1 line compared to the D2 line. This is mainly caused by a different number of hyperfine levels contributing to the excitation process. In our case the excited state 52P1/2 of the

49

D1 line has half of hyperfine levels compared to the excited state 52P3/2 of the D2 line. In the latter case not all excited state levels contribute to the preparation of the CPT resonances. Those levels, being not involved in the CPT resonance creation, will lead to a decreased excitation efficiency of the atomic level population into the dark states. As a consequence, in the case of the D2line excitation the contrast of the CPT resonances is reduced significantly. For this reason the D1 line excitation is preferable in applications like compact CPT atomic clocks and magnetometers.

AMP-7 HS 414, Do, 9 Sept. 2010, 14:15 Uhr

Ab Initio Spin Densities of Small Alkali-Metal Doped Helium Droplets

T. Gruber, A. W. Hauser and W. E. Ernst

Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria, [email protected]

In recent experiments of our group on alkali-metal-doped helium droplets, it could be shown that the hyperfine structure of the dopants is strongly affected by the helium surrounding. [1] A change of the hyperfine splitting of 39K is observed as a function of the nozzle temperature, indicating a dependence on the helium droplet size. Hence we started a theoretical investigation based on an open shell coupled cluster approach to study this size effect within molecular orbital theory. In our theoretical model we are restricted to very small HeNX clusters (N=1-5,X=Li,Na,K) due to the high computational demands of the chosen method. However, it is possible to identify two antagonistic effects of the helium surrounding on the electronic wavefunction of the alkali dopant: The first effect is a compression of the wavefunction which leads to higher spin densities | 0|2 at the core, the second one is a reduction of | 0|2 due to the Pauli repulsion, i.e. the deformation of the s-orbitals.Despite of the computational limitations we also try to give estimations for larger systems. Here we apply a combination of the quantum chemistry approach with a stochastic geometry optimization. Assuming only two-body-interactions we use the simulated annealing technique to obtain geometry predictions.

References [1] Koch, M., Auböck, G., Callegari, C., Ernst, W. E., “Coherent spin

manipulation and ESR on superfluid helium nanodroplets”, Physical Review Letters 103(3), 035302–1–4(2009)

50

AMP-8 HS 414, Do, 9 Sept. 2010, 14:30 Uhr

Towards the Generation of Entangled Photon Pairs in Microcavities

P. Cristofolini, Z. Vörös and G. Weihs

Photonik Gruppe, Institut für Experimentalphysik, Universität Innsbruck Technikerstrasse 25d, A-6020 Innsbruck, Österreich E-Mail: [email protected]

Quantum wells (QWs) placed at the antinodes of a semiconductor microcavity are an interesting system to study light-matter interactions and cavity QED in a solid state environment. Because of their small size and the ease of incorporating them into integrated optics setups, semiconductor microcavities can be used as an efficient, small and fast source of entangled photons [1] for quantum computation and cryptography. In the strong coupling regime of quantum well excitons and cavity photons, the system can be described as consisting of polaritons, new quasiparticles with interesting properties. Several schemes have been proposed to generate entangledphotons [2] using polariton-polariton scattering. All of them require a good control of the excitation laser's parameters. We built a new experimental apparatus using a spatial light modulator (SLM) to steer one or multiple beams without moving any mechanical parts. In this way we can precisely control the excitation angle, its spot size and position on the sample. In the future we will perform state tomography in order to measure the degree of entanglement of the generated pairs.

References [1] W. Langbein, Polariton “Correlation in microcavities produced by parametric

scattering”, Phys. Stat. Sol., 242(11):2260_2270, July 2005. [2] C. Ciuti, “Branch-entangled polariton pairs in planar microcavities and photonic

wires”, Phys. Rev. B, 69(24):245304, Jun 2004.

AMP-9 HS 414, Do, 9 Sept. 2010, 14:45 Uhr

Photoionization of Rb Atoms on He Nanodroplets

F. Lackner 1, M. Theisen¹, and W. E. Ernst1

1Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, Graz, 8010, Austria, [email protected]

Ionization experiments of Rb doped onto superfluid He nanodroplets are presented. Rb atoms on the surface of helium droplets were photoionized by means of one photon ionization, and via resonant two step ionization (with the 52P1/2 and 52P3/2state as intermediate states). The two step ionization has the advantage of being

51

selective for Rb monomers. The Rb atom in the 52P1/2 state remains on the droplet while the one in the 52P3/2 state detaches from the droplet [1]. The ionization products were monitored with a time-of-flight mass spectrometer. At low masses the formation of Rb+-HeN (N<20) complexes was observed except in the case of two step ionization via the 52P1/2 state. The detection of very high masses, up to several thousand amu, indicates the formation of stable Rb+-HeN(e.g., N=1500) complexes. We conclude therefore that the Rb+ is immersed in the He droplet subsequently to the ionization process.

References [1] Auböck, G., Nagl, J., Callegari, C., Ernst, W.E.,”Electron Spin Pumping of

Rb Atoms on He Nanodroplets via Nondestructive Optical Excitation”,Physical Review Letters 101, 035301 (2008)

AMP-10 HS 414, Do, 9 Sept. 2010, 15:00 Uhr

Plasma Generation by Combination of Two Laser Wavelengths

E. Schwarz, G. A. Reider, A. Kremsner and E. Wintner

Photonics Institute, Vienna University of Technology, Gusshausstrasse 25-29, 1040 Wien, Austria E-mail: [email protected]: [email protected] E-mail: [email protected]: [email protected]

Engine concepts of the future have to aim for an increase in efficiency going along with a simultaneous reduction of detrimental exhaust components (CO, CHx, NOxand soot). One promising idea to reach these goals is the concept of laser-induced ignition for combustion engines. Generally, a laser-ignition system offers a multitude of advantages e.g. the probability to ignite leaner mixtures is higher. As a consequence of the high leanness of the mixtures, the flame temperature is lowered and hence also the NOx-emissions, whereas the efficiency of the engine can be increased. For electric spark ignition the spark voltage has to be raised with increasing pressure, which causes stronger erosion of the electrodes. Laser ignition systems do not require electrodes and hence maintenance costs of a laser ignition system are expected to be significantly lower than those of a spark plug system [1]. Customary lasers are, because of their overall size and high initial costs, only applicable for laboratory test rigs and cannot fulfill the needs of an ignition laser. Therefore, it was necessary to develop a compact and robust ignition laser by ourselves which can deliver the pulse energy required to ensure reliable ignition. The outcome was a compact high peak power, passively Q-switched, longitudinally diode-pumped solid-state laser [2]. The next challenge will be to optimize the laser system in regard of efficiency and costs.

52

To improve the laser system systematic studies to reduce the laser pulse energy for plasma generation (MPE) were achieved. The influence of the laser wavelength on the plasma formation has been studied extensively in previous experimental and theoretical studies [3]. Summarized briefly, a shorter wavelength can be focused to a smaller spot size which reduces the threshold for plasma formation while the plasma absorption for a longer wavelength is much better. With a coherent superposition of an infrared-laser pulse and its second harmonic, the threshold of plasma formation as well as the energy transfer efficiency from the laser field to the plasma can be significantly improved in comparison to purely monochromatic radiation. The first time we present experimental results concerning coherence effects in two color laser plasma generation in air at atmospheric pressure.

References [1] H. Kopecek, E. Wintner, M. Lackner, F. Winter, and A. Hultqvist, Laser-

Stimulated Ignition in a Homogeneous Charge Compression Ignition Engine. SAE SP. 1819, 183 (2004).

[2] H. Kofler, J. Tauer, G. Tartar, K. Iskra, J. Klausner, G. Herdin, and E. Wintner, An Innovative solid-state laser for engine ignition. Laser Physics Letters. 4(4), 322 (2006).

[3] L.J. Radziemski and D.A. Cremers, Laser-Induced Plasmas and Applications. 1 ed. Optical Engineering, ed. B.J. Thompson (Marcel Dekker Inc., New York, 1989).

AMP-11 HS 414, Do, 9 Sept. 2010, 15:15 Uhr

A Composite Parameterization of Unitary Groups, Density Matrices and Subspaces

Ch. Spengler, M. Huber and B. C. Hiesmayr

Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria [email protected],[email protected],[email protected]

Many quantities in quantum physics are related to optimization problems that necessitate to vary over the set of all unitary transformations, density matrices or subspaces. Problems of this kind arise, for instance, in the field of quantum information in the detection, classification and quantification of entanglement (see [1, 2, 3] and references therein), finding optimal measurement settings for quantum states with respect to Bell inequalities [4, 5] and the study of (n-copy) distillability [6, 7]. All these tasks can be considerably simplified by using adequate parameterizations of the central objects. Here we introduce a non-redundant composite parameterization [8] of the unitary group U(d) for arbitrary dimension d

53

whose building blocks are matrix exponential functions of generalized anti-symmetric sigma-matrices and one-dimensional projectors. The specific form of this parameterization has several advantages with respect to numerical tractability and the identification of irrelevant parameters concerning a vast number of problems. It enables us to formulate redundancy-free density matrices of arbitrary rank k. Furthermore, we show how the parameterization can be used to construct and cover all k-dimensional orthonormal subspaces of C^d with the minimal number of parameters. As an example it will be shown that this feature paves the way for numerically investigating distillability of high-dimensional quantum systems.

References[1] Gühne O. and Tóth G., “Entanglement detection”, Physics Reports 474,

1 (2009) [2] Horodecki R., Horodecki P., Horodecki M. and Horodecki K., “Quantum

entanglement“, Rev. Mod. Phys. 81, 865 (2009) [3] Huber M., Mintert F., Gabriel A. and Hiesmayr B.C., “Detection of high-

dimensional genuine multi-partite entanglement of mixed states”, Phys. Rev. Lett. 104, 210501 (2010)

[4] Son W., Lee J., and Kim M.S., “d-outcome measurement for a nonlocality test”, J. Phys. A: Math. Gen. 37, 11897 (2004)

[5] Spengler Ch., Huber M., and Hiesmayr B.C., “On the state space geometry of the CGLMP-Bell inequality”, arXiv:0907.0998 (2009)

[6] Horodecki M., Horodecki P., and Horodecki R., “Mixed-State Entanglement and Distillation: Is there a “Bound” Entanglement in Nature?”, Phys. Rev. Lett. 80, 5239 (1998)

[7] Dür W., Cirac J.I., Lewenstein M. and Bruss D., “Distillability and partial transposition in bipartite systems”, Phys. Rev. A 61, 062313 (2000)

[8] Spengler Ch., Huber M. and Hiesmayr B.C., “A composite parameterization of unitary groups, density matrices and subspaces”, arXiv:1004.5252 (2010)

54

8.4 FAKT (KTP) – Fachausschuss Kern- und Teilchenphysik



Parallel Session FAKT (Topic LHC)

Zeit Time



9:00 9:10 Kajetan Fuchsberger(CERN) Status of the LHC beam commissioning

9:10 9:20 Franz Mittermayr (HEPHY ÖAW) Status of the CMS experiment at CERN

9:20 9:30 Christian Thomay (HEPHY ÖAW)

Commissioning of the b-jet identification in CMS

9:30 9:40 Edmund Widl (HEPHY ÖAW)

Preparation for supersymmetry searches at CMS:

Jets and missing energy

9:40 9:50 Thomas Bergauer (HEPHY ÖAW)

Operation of the CMS Tracker at the Large Hadron Collider

9:50 10:00 Valentin Knünz (HEPY ÖAW)

Measurement of quarkonium production at CMS

10:00 10:10 Erik Huemer (HEPHY ÖAW)

Upgrade of the CMS tracker for hHigh luminosity operation

10:10 10:20 Elmar Ritsch (Univ. Innsbruck)

Simulation of Calorimeter Punch – Through Particles in ATLAS

55

10:20 10:30 Patrick Jussel (Univ. Innsbruck)

First observations of J/ + and D(*)

mesons in pp collisions at s = 7 TeV in the ATLAS experiment

10:30 10:40 Wolfgang Kiesenhofer (HEPHY ÖAW)

Muon reconstruction for SUSY searchers at CMS



Fachausschuß Kern- und Teilchenphysik - Scientific Committee Nuclear and Particle Physics (FAKT)

Parallel Session FAKT (Topic Theory)

Zeit Time



13:30 13:50 Reinhard Alkofer (Univ. Graz)

On baryon properties from QCD bound-state equations

13:50 14:00 Beatrix Hiesmayr (Univ. Wien)

Testing foundations of quantum mechanics in particle physics

14:00 14:10 Marcus Huber (Univ. Wien)

Detection and classification of genuine multipartite entanglement in high-

dimensional mixed states

14:10 14:20 Andreas Krassnigg (Univ. Graz)

Toward a comprehensive meson spectroscopy with the Bethe-Salpeter

equation

14:20 14:30 Martina Blank (Univ. Graz)

From (in)homogeneous Bethe-Salpeter amplitudes to observables

56

14:30 14:40 Sabine Ertl (TU Wien)

All stationary axi-symmetric solutions to topologically massive gravity

14:40 14:50 Branislav Cvetkovi(Institute of Physics,

Belgrade) Canonical structure of new massive gravity

14:50 15:00 Harold Steinacker (Univ. Wien)

Emergent Geometry and Gravity from Yang-Mills Matrix Models

CANCELLED

15:00 15:10 Wolfgang

Waltenberger (HEPHY ÖAW)

Towards a description of physics beyond the standard model with on-shell

effective theories


Parallel Session FAKT (Topic Plan)

16:30 - 16:45 Michael Benedikt (CERN) Status of the MedAustron Project

16:45 - 17:00 Christian Fabjan (TU Wien)

The Physics Cluster for Atomic and Subatomic Physics

17:00 18:00 Jahreshauptversammlung des

Fachausschusses FAKT FAKT Annual General Assembly


18:30 20:00 Robert Schöfbeck (HEPHY ÖAW)

Sterne - Kerne – Teilchen Eine Reise von den kleinsten Teilchen bis zu den Grenzen des Weltalls auf der der

Suche nach der neuen Physik

57

Freitag - Friday 10 September 2010 / Audi Max


Parallel Session FAKT (Topic Experiment)


9:00 9:20 Olaf Hartmann (SMI ÖAW) The FOPI Experiment at GSI-SIS

9:20 9:30 Tobias Jenke (TU Wien)

Rabi spectroscopy and excitation in a gravity cavity of neutron matter waves

9:30 9:40 Xiangzun Wang (TU Wien) Standard model tests with PERC

9:40 9:50 Barbara Wünschek (SMI ÖAW)

Status and plans of experiment E17 at J-PARC

9:50 10:00 Claudia Lederer (Univ. Wien)

New measurement of the 62Ni(n, ) cross-section with n_TOF at CERN relevant for

the astrophysical s-process

10:00 10:10 Klaus Mair (Univ. Wien)

Developments towards Radiocarbon Dating of ultra-small DNA samples

10:10 10:20 Martin Martschini (Univ. Wien)

Recent advances in AMS of 36Cl with a 3-MV-Tandem

10:20 10:30 Oswald Massiczek (SMI ÖAW)

A new cryogenic target and microwave cavity for hyperfinestructure spectroscopy

of antiprotonic helium

10:30 10:40 Susanne Friedreich (SMI ÖAW)

Hyperfine structure spectroscopy with antiprotonic helium

58

10:40 10:50 Stefan Pavetich (Univ. Wien)

AMS measurement of the reaction 35Cl(n, )36Cl and its relevance to

astrophysics and nuclear technology


Parallel Session FAKT (Topic Detector + Software)

11:30 11:40 Wolfgang Frisch (HEPHY ÖAW)

HFOLD a program package for calculating MSSM two-body Higgs decays at full

one-loop level

11:40 - 11:50 Natascha HörmannUsing Vienna Tier-2 Grid computing for data analysis of the CMS experiment and for other

research projects

11:50 - 12:00 Robert Fröschl(CERN)

JEREMY – a code for radiological characterization of accelerator components

at CERN

12:00 - 12:10 Denise Neudecker (TU Wien)

GENEUS - A program designed for nuclear data evaluations

12:10 - 12:20 Gamal Ahmed (SMI ÖAW)

Silicon photomultiplier for subatomic physics experiments

- performance studies at SMI

12:20 - 12:30 Imanuel Gfall (HEPHY ÖAW)

Belle II silicon vertex detector: mechanics and cooling

12:30 - 12:40 Jürgen Pfingstner (CERN)

Ground motion mitigation in the main linac of CLIC

12:40 12:50 Philipp Müllner (SMI ÖAW)

Gem detector development for hadron-physics experiments

12:50 - 13:30 FAKT Fachtagung Zusammenfassung FAKT Session Summary

59

FAKT-1 Audi Max: 9 Sept. 2010, 9:00 Uhr

Status of LHC Beam Commissioning

K. Fuchsberger

CERN, 1211 Genève 23, Switzerland, BE-OP-SPS, [email protected]

After the incident on the 19th September 2008 and more than one year without beam the commissioning of the LHC started again on November 20, 2009. Progress was rapid and collisions under stable beam conditions were established at 1.2 TeV within 3 weeks. In 2010 after qualification of the new quench protection system the way to 3.5 TeV was open and collisions were delivered at this energy after a month of additional commissioning. Currently commissioning for unsafe beams is in progress. Intensity increase will be done in steps, each of them followed by an extended running period. We describe the experiences and issues encountered during these first periods as well as the current status of commissioning with beam.

FAKT-2 Audi Max: Do, 9 Sept. 2010, 9:10 Uhr

Status of the CMS Experiment at CERN

F. Mittermayr1, CMS Collaboration2

1 Institute of High Energy Physics of the Austrian Academy of Sciences Nikolsdorfer Gasse 18, 1050 Vienna, Austria [email protected], 1211 Geneva 23, Switzerland

The Large Hadron Collider (LHC) at CERN is now in operation and providing steady particle beams at an energy of 3.5 TeV giving CMS the chance to observe already known phenomena as well as enabling early searches for new physics. The CMS collaboration has already published papers on real collision data. This talk will give an overview of the latest developments in CMS’ operation, performance and the results already achieved at half the LHC design energy by the physics teams.

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Commissioning of the b-jet Identification in CMS

C. Thomay

Institut for High Energy Physics, Austrian Academy of Sciences Nikolsdorfer Gasse 18, A-1050 Wien [email protected]

The identification of jets containing products of the decay of a B-hadron is a key component in the analysis of proton-proton-collisions at the LHC, both for measurements in the framework of the standard model and for searches for New Physics. First data recorded by the CMS experiment have been used to compare the distributions of observables used in the identification, such as impact parameters of tracks and reconstructed decay vertices, with the expectations from simulation. Preliminary measurements of the performance of the algorithms in terms of efficiency and mis-identification rates are also shown.


Preparation for Supersymmetry Searches at CMS: Jets and Missing Energy

E. Widl1 and R. Schöfbeck2

Institute of High Energy Physics of the Austrian Academy of Sciences Nikolsdorfer Gasse 18, A-1050 Vienna, Austria [email protected], [email protected]

Searches for supersymmetry [1] have to deal with a broad range of signatures on top of a large variety of background processes with cross-sections expected to be some orders of magnitude bigger than the actual signal. Therefore one requires a good understanding of the corresponding physics observables and careful control over backgrounds from standard model processes. For this purpose the first proton-proton collision data at a center-of-mass energy of 7 TeV recorded by the CMS experiment [2] have been used to study the performance of the reconstruction of jets and missing energy [3,4]. The methods developed for data-driven background estimation have been tested to study QCD backgrounds and to validate predictions of background distributions [5]. All results have been compared with predictions from simulation.

References [1] Martin, S., “A Supersymmetry Primer”, arXiv:hep-ph/9709356v5[2] CMS Collaboration, “The CMS Experiment at the CERN LHC”, JINST 3,

61

S08004 (2008) [3] CMS Collaboration, “CMS Jet Performance in pp Collisions at s = 7 TeV”,

CMS Physics Analysis Summary, CMS PAS JME-10-003 [4] CMS Collaboration, “CMS MET Performance in Jet Events from pp

Collisions at s = 7 TeV”, CMS Physics Analysis Summary, CMS PAS JME-10-004

[5] CMS Collaboration, “Performance of Methods for Data-Driven Background Estimation for SUSY Searches in the CMS Experiment”, CMS Physics Analysis Summary, CMS PAS SUS-10-001


Operation of the CMS Tracker at the Large Hadron Collider

W. Adam, T. Bergauer, M. Dragicevic, M. Friedl, R. Frühwirth, St. Hänsel, M. Hoch, J. Hrubec, M. Krammer, M. Pernicka, E. Widl

Institut für Hochenergiephysik der ÖAW, Nikolsdorfer Gasse 18, 1040 Wien [email protected]

The inner tracking detector of the Compact Myon Solenoid (CMS) Experiment at CERN is the largest semiconductor tracking device built so far. It consists of more than 25,000 individual silicon sensors with a total active area of almost 200 square meters. Its design, construction and commissioning was a huge effort of more than 50 institutes around the world and lasted almost seven years. The institute of High Energy Physics (HEPHY) of the Austrian Academy of Sciences contributed significantly to this project since its beginning by working on both the silicon strip and the pixel detectors. With the start of normal operation of the Large Hadron Collider (LHC), the CMS Tracker became operational as a scientific device and as part of the CMS experiment during data taking. Operation experience is gained continuously as the LHC delivers proton-proton collisions. In this presentation all critical systems of the tracker will be summarized and performance data will be presented. These numbers will show that both, the tracker and the whole experiment are working extremely well. First physics plots are already emerging, like measurements of the masses of different well-known particles. These measurements are helpful in calibrating the detector to be well prepared for the discovery of new physics as the LHC continues to deliver collision data.

62


Measurement of Quarkonium Production at CMS

V. Knünz

Institut of High Energy Physics, Austrian Academy of Sciences Nikolsdorfer Gasse 18, A-1050 Vienna E-mail: [email protected]

Since early 2010 the CMS experiment is recording proton-proton collisions at the yet unexplored energy of 7 TeV. This talk presents the first measurements of J/Psi and Upsilon production at this energy. The techniques used for event selection and reconstruction are shown and an outlook on future measurements with quarkonia states will be given.


Upgrade of the CMS Tracker for High Luminosity Operation

G. Auzinger, M. Bernard-Schwarz, T. Bergauer, M. Dragicevic, M. Friedl, S. Hänsel, E. Huemer1, J. Hrubec and M. Krammer


The CMS experiment is one of the four large experiments which are currently carried out at the Large Hadron Collider (LHC) at CERN. The innermost detector system, the so-called tracker, is performing with high efficiency and delivers an important contribution to the reconstruction of the physics processes governing the collision of protons with a center-of-mass energy of 14 TeV. An upgrade of the accelerator is planned around 2020, which will boost the luminosity by a factor of ten and will cause a significant increase of the interaction rate. In turn, this will also increase the number of background interactions which has significant impact on the performance of the system to select interesting events (the trigger) and the tracker. To cope with the larger number of particles per collision, the number of sensor elements in the tracker has to be increased while reducing the overall material budget of the detector system. Furthermore, the lifetime of the current tracker is already limited by the harsh radiation environment in the center of the detector to 10 years of operation at the current design luminosity. For the subsequent operation of a new tracker at high luminosity, entirely new sensor materials are needed, which are able to withstand the tenfold increase in irradiation. The Institute of High Energy Physics (HEPHY) is significantly involved in the research and development of the new CMS tracker for high luminosity

63

operation. This talk will give a short introduction on the main challenges for the new detector, followed by a presentation of the newest developments on silicon strip sensors which are designed and investigated at HEPHY.


Simulation of Calorimeter Punch-Through Particles in ATLAS

E. Ritsch1, A. Salzburger2 and E. Kneringer1

1Universität Innsbruck, Institut für Astro- und Teilchenphysik Technikerstrasse 25, 6020 Innsbruck, [email protected], 1211 Geneva 23, Switzerland

In the ATLAS detector the electromagnetic and hadronic calorimeters should confine any strongly interacting particle type. Therefore mostly muons pass through the calorimeters and create signals in the muon system (MS). Due to interactions in the calorimeters, there is a certain probability that any high energetic particle (other than a muon) creates child-particles which have enough energy to leave the calorimeter and enter the MS. These so called punch-through particles will then create signals in the MS which can be misinterpreted as signals coming form muons originating from the proton-proton interaction point. This effect is studied with full Geant4 Monte Carlo simulations and a parametrised and simplified model is implemented in FATRAS which is a fast ATLAS simulation software.


First Observations of J/ + and D(*) Mesons in pp Collisions at s = 7 TeV in the ATLAS Experiment

P. Jussel, E. Kneringer and D. Kuhn

Universität Innsbruck, Institut für Astro- und Teilchenphysik Technikerstrasse 25, 6020 Innsbruck [email protected]

In the ATLAS [1] detector at the LHC the decay channel J/ + is measured [2] using proton-proton collisions at a centre of mass energy of s = 7 TeV. The resonance and the combinatorial background are fitted using an unbinned maximum likelihood method. The reconstructed invariant mass and peak width are compatible with PDG world-average values as well as Monte Carlo expectations. The kinematic properties of the J/ and trigger efficiencies are presented.

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In addition, hadronic decays of D*±, D(±) and Ds± mesons are reconstructed [3] at the

ATLAS using the same dataset. Also those measurements are in good agreement with the PDG values.

References [1] The ATLAS Collaboration; Expected performance of the ATLAS experiment :

detector, trigger and physics; arXiv:0901.0512, CERN-OPEN-2008-020 (2008).

[2] The ATLAS Collaboration; First observation of J/ + resonance in the ATLAS pp collisions at s = 7 TeV; submitted for CONF Notes for PLHC2010 (2010).

[3] The ATLAS Collaboration; D(*) meson reconstruction in pp collisions at s = 7 TeV; submitted for CONF Notes for PLHC2010 (2010).


Muon Reconstruction for SUSY Searches at CMS

W. Kiesenhofer

Institut of High Energy Physics, Austrian Academy of Sciences Nikolsdorfer Gasse 18, A-1050 Vienna E-mail: [email protected]

Searches for supersymmetry (SUSY) involve a broad range of signatures including events featuring isolated muons. Studying those decay channels has the advantage that the dominating standard model QCD background can be relatively well suppressed. Nonetheless a careful evaluation of muon reconstruction is necessary that involves the measurement of detection and trigger efficiencies as well as muon fake rates, which pose a major contribution to the background. This talk gives an overview about the specific way CMS measures muons and summarizes several methods used to estimate efficiencies and fake rates as well as results from their application on first data.


On Baryon Properties from QCD Bound-State Equations

H. Sanchis Alepuz1, R. Alkofer1, S. Villalba Chavez1 and Gernot Eichmann2

1IInst. Physics, Graz University, 8010 Graz, Austria; [email protected]. Nuclear Physics, TU Darmstadt, D 64289 Darmstadt, Germany

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Employing an approach based on the Green functions of Landau-gauge QCD some selected results from calculations of baryon properties are presented. Hereby a rainbow-ladder truncation to the quark Dyson-Schwinger equation is used to arrive at an unified description of mesons and baryons by solving Bethe-Salpeter and covariant Faddeev equations, respectively, see [1,2] and references therein.

References [1] G. Eichmann, R. Alkofer, A. Krassnigg, D. Nicmorus, “Nucleon mass from a

covariant three-quark Faddeev equation”, Phys. Rev. Lett. 104 (2010) 201601 [arXiv: 0912.2876 [hep-ph]]

[2] G. Eichmann, “Hadron properties from QCD bound-state equations”, Ph.D. Thesis, University of Graz [arXiv:0909.0703[hep-ph]]


Testing Foundations of Quantum Mechanics in Particle Physics

T. Adaktylos1, A. Gabriel1, B.C. Hiesmayr12, F. Hipp1, M. Huber1, G. Krizek1,S. Radic1, H. Schimpf1, Ch. Spengler1 and H. Waldner1

1University of Vienna, Faculty of Physics, Botzmanngasse 5, A-1090 Vienna 2 University of Sofia, Faculty of Physics, Blvd. James Bourchier 5, 1164 Sofia, Bulgaria

Particle physics has become an interesting testing ground for questions of foundations of quantum mechanics. Entangled massive meson-antimeson systems are specially suitable as they offer a unique laboratory to test various aspects of particle physics (CP violation, CPT violation,. . . ) as well to test foundations of quantum mechanics, e.g. Bell inequalities [1, 2, 3, 4], decoherence effects [5, 6], quantum marking and erasure concepts [7, 8], Bohr's complementary relation [9, 10]. The main aim of this talk is to show that these systems not consisting of ordinary matter and light provide novel insights into quantum theory. Particularly, we show that a certain Bell inequality is related to the observed tiny difference between matter and antimatter [3, 4], the so called CP violation explored in particle physics. Herewith two different powerful concepts in physics, entanglement or its manifestation and symmetry, become related. Then we show a Bell inequality sensitive to the quantum number strangeness [3], which is not violated for the maximally entangled spin singlet state, but surprisingly for a non-maximally entangled state [1]. This opens for the first time the possibility of a direct experimental. We will shortly discuss the status quo of the realization [11] with the upgraded KLOE detector (DAPHNE machine, Italy). In summary, understanding the nature of entanglement and its manifestation needs also studies of entanglement at different energy scales and as recent works show there are still many open questions concerning entanglement, e.g. about high dimensional genuine

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multipartite entanglement [12] or of relativistic entanglement of massive spin 1/2 particles [13].

References [1] B.C. Hiesmayr: Nonlocality and entanglement in a strange system.European

Physical Journal C, Vol. 5073-79 (2007). [2] B.C. Hiesmayr: A generalized Bell inequality and decoherence for the K0

anti-K0 system. Found. of Phys. Lett. 14, 231 (2001). [3] R.A. Bertlmann and B.C. Hiesmayr: Bell inequalities for entangled kaons

and their unitary time evolution. Phys. Rev. A 63, 062112 (2001). [4] R.A. Bertlmann, W. Grimus and B.C. Hiesmayr: Bell inequality and CP

violation in the neutral kaon system. Phys. Lett. A 289, 21 (2001). [5] R.A. Bertlmann, K. Durstberger and B.C. Hiesmayr.: Decoherence of

entangled kaons and its connection to entanglement measures.Phys. Rev. A 68, 012111 (2003).

[6] R.A. Bertlmann, W. Grimus and B.C. Hiesmayr: Quantum mechanics, Furry's hypothesis and a measure of decoherence. Phys. Rev. D 60, 114032 (1999).

[7] A. Bramon, G. Garbarino and B.C. Hiesmayr: Quantum marking and quantum erasure for neutral kaons. Phys. Rev. Lett. 92,020405 (2004)

[8] A. Bramon, G. Garbarino and B.C. Hiesmayr: Active and pas- sive quantum eraser for neutral kaons. Phys. Rev. A 69, 062111 (2004).

[9] B.C. Hiesmayr and M. Huber: Bohr's complementarity relation and the violation of the CP symmetry in high energy physics. Physics Letters A, 372 (20), 3608 (2008).

[10] A. Bramon, G. Garbarino and B.C. Hiesmayr.: Quantitative complementarity in two-path interferometry, Phys. Rev. A 69, 022112 (2004).

[11] G. Amelino-Camelia et.al: Physics with the KLOE-2 experiment at the upgraded DAPHNE. Accepted by Physical Journal C or arXiv:1003.3868.

[12] M. Huber, F. Mintert, A. Gabriel and B.C. Hiesmayr. Detection of high-dimensional qenuine multi-partite entanglement of mixed state. Phys. Rev. Lett. 104, 210501 (2010).

[13] N. Friis, R.A. Bertlmann, M. Huber, B.C. Hiesmayr. Relativistic entanglement of two massive particles. Phys. Rev. A81, 042114 (2010)


Detection and Classification of Genuine Multipartite Entanglement in High-Dimensional Mixed States

M. Huber1, Andreas Gabriel2 and Beatrix Hiesmayr3

1University of Vienna, Boltzmanngasse 5, A1090 Vienna, [email protected] of Vienna, Boltzmanngasse 5, A1090 Vienna 3University of Vienna, Boltzmanngasse 5, A1090 Vienna

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We present a general framework to identify genuinely multipartite entangled mixed quantum states in arbitrary-dimensional systems and show on exemplary cases that the constructed criteria are stronger than previously known ones. Our criteria are simple inequalities involving matrix elements of the given quantum state and detect genuine multi-partite entanglement that had not been identified so far. They are experimentally accessible without quantum state tomography and are easily computable as no optimization or eigenvalue evaluation is needed. We also provide an optimal way for constructing the observables needed to identify the separability. Also we show that with such inequalities it is possible to distinguish certain classes of genuinely multipartite entangled states, e.g. the GHZ and W class. Furthermore these criteria prove to be versatile tools for detecting separability with respect to different partitions of multipartite states and provide novel ways of deriving lower bounds on concurrence based entanglement measures. In the end we show how with the help of such a framework, one can go further and not only identify genuine multipartite entanglement, which is constituted by non-2-separability, but generalize it to achieve criteria for non-k-separability in arbitrary dimensional multipartite states.

References [1] M. Huber, F.Mintert, A. Gabriel and B.C. Hiesmayr, „Detection of High-

Dimensional Genuine Multipartite Entanglement of Mixed States“, Phys. Rev. Lett. 104, 210501 (2010)

[2] A. Gabriel, B.C. Hiesmayr and M, Huber, „Criterion for k-separability in mixed multipartite systems“, arXiv/quant-ph: 1002.2953


Toward a Comprehensive Meson Spectroscopy with the Bethe-Salpeter Equation

A. Krassnigg1 and M. Blank1

1Institut f. Physik, University of Graz, Universitätsplatz 5, A 8010 Graz, Austria, [email protected]

The Bethe-Salpeter equation is used embedded in the Dyson-Schwinger equations of quantum chromodynamics to construct an as-complete-as-possible phenomenology of meson spectra. This includes both light quarks and related phenomena such as the effects of dynamical chiral symmetry breaking, as well as heavy quarks and the study of quarkonia in the same framework [1]. The goal is to connect these realms and to identify interesting states in each case, thus laying the fundament for meson (and also baryon) studies beyond spectroscopy.

References [1] Krassnigg, A., “Survey of J=0,1 mesons in a Bethe-Salpeter approach”,

Phys. Rev. D80, 114010 (2009)

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From (In)Homogeneous Bethe-Salpeter Amplitudes to Observables

M. Blank1, V. Mader1 and A. Krassnigg1

1Institut f. Physik, University of Graz, Universitätsplatz 5, 8010 Graz [email protected]

We investigate properties of light mesons in a Dyson-Schwinger - Bethe-Salpeter approach. In particular, decay constants, hadronic decays, and electromagnetic properties are considered from a phenomenological perspective in the well-established rainbow-ladder truncation. New possible grounds for applications of such investigations are opened via improved calculational and numerical techniques.


All Stationary Axi-Symmetric Solutions to Topologically Massive Gravity

S. Ertl1, D. Grumiller2 and N. Johansson3

1,2,3Institute for Theoretical Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10/136, Vienna, A-1040 1 [email protected] 2 [email protected] 3 [email protected]

A brief overview of 3 dimensional gravity and in particular topologically massive gravity (TMG) will be given, followed by the construction of its stationary axi-symmetric version. With this reduced theory all solutions to TMG can be classified into 4 different sectors: Einstein, Schrödinger, warped and generic. The solutions to the first three sectors can be constructed explicitly whereas the generic sector needs numerical examination. Some examples of solutions will be shown including solitons that asymptote to warped AdS.

References [1] Ertl, Grumiller, Johansson, “All stationary axi-symmetric local solution of

topologically massive gravity”, submitted to Class.Quant.Grav

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Canonical Structure of New Massive Gravity

M. Blagojevi 1 and B. Cvetkovi 1,2

1Institute of physics, P.O. Box 57, 11001 Belgrade, Serbia 2Institute for Theoretical Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10/136, Vienna, A-1040, Austria Email: [email protected], [email protected]

We construct the first-order Lagrangian for new massive gravity (NMG) [1] and use the covariant expression for the conserved charges proposed by Nester [2] to calculate the energy and angular momentum of the maximally symmetric solution.We use the full power of Dirac's method for constrained Hamiltonian systems to show that the dimension of the physical phase space is four per spacetime point, which corresponds to two Lagrangian degree of freedom [3]. The analysis of the AdS asymptotic region confirms that the asymptotic symmetry is described by two independent Virasoro algebras with classical central charges.

References [1] Bergshoeff E, Holm O. and Townsend P., “Massive gravity in three

dimensions”, Phys.Rev.Lett. 102: 201301 (2009) [2] Nester J. M. , ”A covariant Hamiltonian for gravity theories”, Mod. Phys. Lett.

A 6 2655(1991) [3] Blagojevi M. And Cvetkovi B., in preparation.


Emergent Geometry and Gravity from Yang-Mills Matrix Models

H. Steinacker

Universität Wien, Physik E-Mail: [email protected]

Matrix Models of Yang-Mills type provide a remarkable pre-geometric approach to geometry and gravity. Space-time is described as a non-commutative brane solution of the model, i.e. as sub-manifold of R^D. Gauge fields, scalar fields and matter arise on the brane as fluctuations of the matrices around such a background, and couple to aneffective metric interpreted in terms of gravity. We show how curvature and physically relevant geometries can be realized in this framework. Several types of geometries are identified, in particular "harmonic"and "Einstein" type of solutions. The relation to non-commutative gauge theory and the role of UV/IR mixing is explained. The IKKT model with D=10 and close relatives are

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singled out as promising candidates for a quantum theory of fundamental interactions including gravity.


Towards a Description of Physics beyond the Standard Model with On-Shell Effective Theories

W. Waltenberger

HEPHY, ÖAW, Vienna Nikolsdorfergasse 18, A 1040 Wien, Austria [email protected]

With the LHC providing the first inverse nanobarns of proton-proton collision data, a new era of particle physics has started. While most efforts currently concentrate on measurements of standard model physics in this new energy range, the Vienna group also prepares for its search for physics beyond the standard model, with a strong focus on supersymmetric models. Historically, search strategies have been developed around the minimal supergravity (MSUGRA) and the gauge-mediated symmetry breaking (GMSB) models. Recently a new, generic tool has been developed: MARMOSET (mass and rate modeling in on-shell effective theories). It is an event generator that revolves around the construction of simplified on-shell effective Lagrangian terms, which are designed to model LHC data effectively, i.e. without reference to an underlying fundamental theory. These effective Lagrangians put strong constraints on the candidates for a new fundamental theory.

In this talk, the idea of on-shell effective theories will be presented, and its implications for physics analysis at the LHC will be discussed.


Status of the MedAustron Project

M. Benedikt

CERN, CH-1211 Geneva 23, [email protected]

MedAustron is a planned centre for hadron therapy and diagnosis in Austria. The centre is based on a synchrotron which will deliver beams of protons up to 800 MeV/c and carbon ions up to 400 MeV/c per nucleon with intensities of 1010

protons/s and 4.108 ions/s, respectively. Although the accelerator layout is primarily dedicated to clinical application, dedicated beam time for research applications in

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the domain of medical radiation physics, radiation biology and experimental physics is also foreseen. Layout requirements for the medical and research applications are established. Civil engineering design is conducted in Austria, where the accelerator complex is designed in collaboration with CERN. A mandatory Environmental Impact Assessment (Umweltvertraeglichkeitspruefung) is currently for review with the Austrian Authorities. Following the EIA approval expected at the end 2010, ground-breaking is scheduled for early 2011. First beams for application are scheduled for 2014. This presentation will summarize the up-to-date layout of the MedAustron facility, status of the project and outlook on usability for the different applications with emphasize on research activities for experimental physics.


The Physics Cluster for Atomic and Subatomic Physics

H. Abele (Univ. of Technology, Vienna), C.W. Fabjan (ÖAW and Univ. of Technology, Vienna), J. Schmiedmayer (Univ. of Technology, Vienna), E. Widmann (ÖAW)

It is planned to bring together the Institute of High Energy Physics (HEPHY) and the Stefan- Meyer Institute (SMI), forming a new Institute of Particle Physics which will be in close scientific, technological and geographic location to the ‘Atominstitut’ (ATI) of the Univ. of Technology, Vienna . Together, these institutes would form the Physics Cluster for Atomic and Subatomic Physics. At the Physics Cluster we will develop a unique research programme comprising a threefold approach to fundamental problems in particle physics: (1) accelerator-based high-energy physics for direct discoveries, (2) precision studies of the strong interaction searching for new exotic hadronic excitations (3) ultra high precision experiments at low energies with discovery potential not accessible with the conventional methods of particle physics.

In the coming decade research will focus on exploiting the discovery potential at accelerators, LHC and KEK, with emphasis on Physics beyond the Standard Model and on studies of exotic nuclear matter at Frascati, at J-PARC and FAIR. The new research line of ultra high precision experiments will start from present expertise with precision experiments with cold and ultracold neutrons at the ILL or at FRMII, atoms, molecules or nuclear transition. It will focus on observables, which are sensitive to physics beyond the Standard Model, such as the breaking of fundamental symmetries (e.g. C, P and T), the variability of fundamental constants, aspects of gravity and ultra weak interactions or Supersymmetry. We will describe the research aims and the potential this Cluster for Atomic and Subatomic Physics will bring to particle physics.

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FAKT-22 Audi Max: Fr, 10 Sept. 2010, 9:00 Uhr

The FOPI Experiment at GSI-SIS

O. N. Hartmann1, P. Bühler1, K. Suzuki1, and J. Zmeskal1

1Stefan-Meyer-Institut für Subatomare Physik (SMI) der Österreichischen Akademie der Wissenschaften, Boltzmanngasse 3, 1090 Wien

The FOPI experiment [1] at the Schwerionensynchrotron SIS of the GSI Helmholtzzentrum [2] for heavy ion research, located at Darmstadt, Germany, is a detector for charged particles emerging from nuclear reactions, induced by heavy ions or hadrons on a fixed target. It provides nearly full coverage of the solid angle. Already since 1990 the FOPI detector is being operated at the GSI, in subsequent construction phases, where the newest one is a time of flight detector based on timing RPC's installed in 2007. Heavy ion collisions in the energy range from 90 AMeV to 2 AGeV have been studied as well as proton and pion induced reactions. The presentation will contain an overview of the FOPI physics program – the nuclear equation of state, stopping and transparency in heavy ion collisions, in-medium effects of hadrons in the light and the strange quark sector including the search for bound states involving strange mesons. Available results will be discussed and an outlook on future activities will be given. The SMI has joined the FOPI collaboration more recently and contributed special hardware parts for the elementary reactions, which will be briefly discussed as well.

References [1] http://www-fopi.gsi.de [2] http://www.gsi.de


Rabi Spectroscopy and Excitation in a Gravity Cavity of Neutron Matter Waves

T. Jenke1, P. Geltenbort2, H. Lemmel1 and H. Abele1

1Atominstitut TU Wien, Stadionallee 2, 1020 Vienna, Austria 2Institut Laue-Langevin, 6 rue Jules Horowitz, 38042 Grenoble Cedex 9, France

Gravity experiments might provide an answer for the “big questions” about space, time, and a unification of all forces, where - as most physicists believe - space-time is not restricted to four dimensions. Hypothetical extra-dimensions, curled up to cylinders or tori with a small compactification radius should lead to deviations from Newton’s gravitational law at very small distances1. These ideas triggered gravity

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experiments of different kinds, which in the past ten years have validated Newton’s gravitational law down to about 50 μm. The basic problem in searching for new physics at small distances is that the size of the objects under study must be reduced, too, going along with a reduction of signal intensity. At the same time, the electrostatic background increases. Our way out is the interaction of a macroscopic system, here a mirror for neutron reflection, with a pure quantum mechanical system, i.e. the excitation of bound quantum states of a neutron in the gravity potential of the earth. We demonstrate that the method of Rabi spectroscopy2 usually used in atom optics can now be applied to quantum states in the gravity potential of the earth3-5 together with a mechanical or magnetic coupling. This technique allows a precise measurement of quantum mechanical phase shifts of a Schrödinger wave packet bouncing off a hard surface in the gravitational field of the earth. The idea behind this method is that phase shifts in gravity potentials can be related to frequency measurements with unprecedented accuracy. These spectroscopy experiments on gravitation within the qBounce6

measurements are a starting point for experiments linked to string theories with large volume compactifications1 and/or cosmology because Newtonian gravity and hypothetical fifth forces evolve with different phase information and limits on a hypothetical strength can be derived.

References 1. Arkani-Hamed, N., Dimopolos, S. & Dvali, G. Phenomenology, astrophysics

and cosmology of theories with submillimeter dimensions and TeV scale quantum gravity. Phys. Rev. D59, 086004 (1999).

2. Rabi I. I. et. al., The molecular beam resonance method for measuring nuclear magnetic moments. The magnetic moments of 3Li6, 3Li7 and 9F19.Phys. Rev. 55, 526 (1939).

3. Nesvizhevsky, V. V. et. al., Quantum states of neutrons in the Earth’s gravitational field. Nature 415, 299 (2002).

4. Nesvizhevsky, V. V. et. al., Study of neutron quantum states in the gravity field. Eur. Phys. J. C40, 479 (2005).

5. Westphal, A. et. al., A quantum mechanical description of the experiment on the observation of gravitationally bound states. Eur. Phys. J. C51, 367 (2007).

6. Abele, H. et. al., QuBounce: The dynamics of ultra-cold neutrons falling in the gravity potential of the Earth. Nucl. Phys. A827, 593c (2009).

We gratefully acknowledge support from the Austrian Science Fund (FWF) under Contract No. I529-N20 and the German Research Foundation (DFG) within the Priority Programme (SPP) 1491 “Precision experiments in particle and astrophysics with cold and ultracold neutrons“, the DFG Excellence Initiative “Origin of the Universe”, and DFG support under Contract No. Ab128/2-1.

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Standard Model Tests with PERC

X. Wang, PERC Collaboration

Atominstitut, TUW, Stadionallee 2, 1020 Wien, Österreich, [email protected]

We address a number of questions which are at the forefront of particle physics, with main emphasis on the search for new physics beyond the Standard Model of particles physics, and in particular, on the question of unification of all forces shortly after the Big Bang. This grand unification is not part of the Standard Model, and new symmetry concepts are needed like left-right symmetry, fundamental fermion compositeness, new particles, leptoquarks, supersymmetry, and many more.[1] We present a case study on a new type of cold neutron beam station PERC, for the investigation of various observables in free neutron's b-decay. With PERC, we will be able to obtain a beam of decay electrons and protons under well-defined and precisely variable conditions from the cold neutron beam [2]. Therefore the spectra and angular distributions of the emerging decay particles will be distortion-free on the level of 10-4, more than 10 times better than achieved today. PERC is part of a priority program SPP 1491 "Precision experiments in particle and astrophysics with cold and ultra-cold neutron"(FWF, Contract No. I 534-N20)

References [1] H. Abele, "The neutron. Its properties and basic interactions" Prog. Part. Nucl.

Phys., 60, 1 (2008). [2] D. Dubbers at al. "A clean, bright, and versatile source of neutron decay

products", Nucl. Instrum. Meth. A 596, 238 (2008),


Status and Plans of experiment E17 at J-PARC

B. K. Wünschek1

On behalf of the E17 J-PARC collaboration

Stefan-Meyer-Institute for subatomic physics, Boltzmanngasse 3, 1090 Wien, [email protected]

Kaonic helium is an advantageous exotic atom to measure KN interaction at threshold energy. Especially X-ray spectroscopy is useful in order to investigate the shift and width of the energy levels, evoked due to strong interaction between nucleus and Kaon.

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The 2p level shift was determined in kaonic 4He by the KEK-PS E570 experiment in 2007 [1]. The obtained shift of 2 ± 2(stat) ± 2(sys) eV solved the long-standing so-called kaonic helium puzzle: most of the theoretical predictions with optical models estimated a very small shift of 0eV, whereas all previous experiments (1971-1983), obtained a large shift of around -40eV. Although E570 experiment restricted a large shift for kaonic 4He, the case for 3He is not solved yet. Furthermore, crucial information on the isospin dependence of the KN interaction in kaonic helium can be obtained by measuring X-ray transitions in kaonic 3He. In E17, the X-ray transition 3p 2d in liquid kaonic 3He will be measured with high precision at the K1.8BR beam line at J-PARC [2], which is one of the first experiments at J-PARC. To achieve the desired precision of <2eV the principle of the successful setup for E570 will be used, among others the reutilization of Silicon Drift Detectors (SDD). Those Detectors are characterized by their good energy resolution ( 140 eV at 5.9 keV) and time resolution (< 1 s), as well as their thickness of around 500 m which makes these detectors extremely sensitive for low-energy X-rays at high rates.The detectors will be mounted around the liquid 3Hetarget, inside the chamber. Both in Vienna and at KEK in Japan, altogether ten devices were adjusted and subjected to systematic tests in order to optimize them for the experiment. The testing procedure and the arrangement of the devices will be discussed in detail.

References [1] S. Okada, et al., Phys. Lett. B 653 (2007) 387. [2] R.S. Hayano, Proceedings of EXA08/LEAP08, Eds. B. Juhasz, J. Marton,

E. Widmann and J. Zmeskal, Hyperfine Interactions.


New Measurement of the 62Ni(n, ) Cross-Section with n_TOF at CERN Relevant for the Astrophysical S-Process

C. Lederer1, E. Berthoumieux2,3, M. Calviani3, D. Cano-Ott4, N. Colonna5,I. Dillmann6, C. Domingo-Pardo7, G. Giubrone8, C. Guerrero3,4, F. Gunsing2,M. Heil7, E. Jericha10, F. Käppeler9, H. Leeb10, C. Massimi11, A. Mengoni12,A. Pavlik1, J.L Tain8 V. Vlachoudis3, A. Wallner1, Christina Weiß10 and the n_TOF Collaboration

1Faculty of Physics, University of Vienna, Vienna, Austria; 2CEA/Saclay - DSM, Gif-sur-Yvette, France; 3CERN, Geneva, Switzerland; 4CIEMAT, Madrid, Spain; 5INFN, Bari, Italy; 6Faculty of Physics, Technical University Munich, Garching, Germany; 7GSI, Darmstadt, Germany; 8Instituto de Fisica Corpuscular, CSIC-Universidad de Valencia, Valencia, Spain; 9Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany;

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10Atomic Institute, Technical University of Vienna, Vienna, Austria; 11INFN, Bologna, Italy; 12IAEA - Nuclear Data Section, Vienna, Austria;

Neutron capture reactions play a dominant role for building up heavy elements in stellar nucleosynthesis (slow s-process and rapid r-process). The abundance pattern of these elements, specifically their s-process contribution is strongly correlated to neutron capture cross-sections. At present, neutron capture cross-sections for elements of mass numbers 60<A<120 suffer from large uncertainties. The latter directly affect the interpretation of r-process model calculations, because r-process abundances are determined by subtracting the s-process contribution from the solar abundance.In 2009, a campaign to measure all stable Ni and Fe isotopes - the seed nuclei of the astrophysical s-process, at the neutron time-of flight facility n_TOF at CERN has started. At n_TOF, neutrons are produced by spallation reactions of pulsed 20 GeV/c protons on a Pb target. The flight path of approx. 185 m guarantees a high energy resolution. The capture yield over an energy range from1 eV to 1 MeV is measured by detecting the prompt gamma-de-excitation of the compound nucleus with a pair of liquid scintillation detectors featuring low neutron sensitivity. Last year, data taking of the reactions 56Fe(n, ) and 62 Ni(n, ) has been successfully finished and the analysis is ongoing. First results will be presented.


Developments towards Radiocarbon Dating of Ultra-Small Dna Samples

K. Mair, J. Liebl , P. Steier , W. Kutschera

Vienna Environmental Research Accelerator (VERA) Laboratory,Fakultät für Physik – Isotopenforschung, Universität Wien, Währingerstrasse 17, A-1090 Wien, Austria

Radiocarbon (14C) dating using Accelerator Mass Spectrometry (AMS) is a well established method. Standard methods of AMS typically require a sample size of about one milligram carbon, which, however, is not available in our recent efforts towards dating DNA from small human brain tissue samples using the 14C bomb peak [1]. We are presently developing methods to reliably measure samples in the range of ~10 g C. In decreasing the sample size, the main challenge is the control of the laboratory background which typically stays constant, and finally dominates the measurement result. In order to keep carbon contamination at the lowest possible level, an argon atmosphere – instead of air - was provided in sample handling, sample preparation, and ion source loading. Most of these tasks were performed in an argon glove box. Since we couldn’t find a significant difference in the carbon background for the ultra-small samples between sample preparation in laboratory air and argon atmosphere, we tested our argon-controlled set-up with mg-size samples of

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geological graphite (nominally zero 14C content), and found a radiocarbon age of 77 000 years BP. This is the lowest 14C background we have measured at VERA so far. It corresponds to a fraction modern carbon (F14C) value of (6.3 ± 1.4)x10-5. This is about one 14C half life "older" than samples processed in laboratory atmosphere. However, It was not possible to measure such a low value with ~10 μg graphitized carbon samples, because contamination from other sources seems to dominate the overall background. In a different investigation, we studied the mass of carbon contamination incorporated during different steps of sample preparation using small samples highly enriched in 13C. The amount of contamination with normal carbon (99% 12C) present in CO2 from sample combustion can be assessed by measuring 13CO2/12CO2 ratios using an RGA (residual gas analyzer). Additional contamination from the graphitization process was determined by measuring 13C/12C ratios with AMS. An overall amount of 0.12 to 0.15 g C contamination was found in this way [2].

References [1] Spalding, K. L., Bhardwaj, R. D., Buchholz, B. A., Druid, H., Frisen, J.,

“Retrospective birth dating of cells in humans”, Cell 122, 133-143 (2005). [2] Liebl, J., Avalos Ortiz, R., Golser, R., Handle, F., Kutschera, W., Steier. P.,

Wild, E. M., “Studies on the preparation of small 14C samples with an RGA and 13C enriched material”, accepted for publication in Radiocarbon.


Recent Advances in AMS of 36Cl with a 3-MV-Tandem

M. Martschini1,*, O. Forstner1, R. Golser1, W. Kutschera1, S. Pavetich1,A. Priller1, P. Steier1, M. Suter2 and A. Wallner1

1 VERA Laboratory, Fakultät für Physik - Isotopenforschung, Universität Wien, Währingerstraße 17, A-1090 Wien, Austria; *[email protected] 2 Ion Beam Physics, Department of Physics, ETH Zürich, Schafmattstraße 20, CH-8093 Zürich, Switzerland

36Cl (t1/2 = 0.30 Ma) is widely used for exposure dating of carbonate rocks such as limestone and calcite. Accelerator mass spectrometry (AMS) with its high sensitivity allows to measure 36Cl at natural isotopic concentrations (36Cl/Cl ~ 10-13) but requires high particle energies for the separation from the stable isobar 36S. At VERA (Vienna Environmental Research Accelerator) we had performed the first 36Cl exposure dating measurement with a 3-MV tandem accelerator, operating our machine at 3.5 MV, using foil stripping and a split-anode ionization chamber [1]. We evaluated the performance of various detectors for 36Cl [2]. With the ionization chamber and a residual energy signal from a silicon strip detector, we now achieved an equally good 36S suppression at 3 MV terminal voltage compared to 3.5 MV in our previous measurements. To further increase the 36S suppression we

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investigated energy loss straggling in various counting gases and the effect of “energy focusing” [3] below the maximum of the Bragg curve. Comparison of experimental data with simulations and published data [3,4] yielded interesting insight into the physics underlying the detectors. Energy loss, energy straggling and angular scattering determine the 36S suppression. In addition, we improved ion source conditions, target backing materials and the cathode design with respect to sulfur output and cross contamination. These changes allow higher currents during measurement (35Cl current 5 A) and also increased the reproducibility. We achieve an injector to detector efficiency for 36Clions of 8% (16% stripping yield for the 7+ charge state in the accelerator, 50% 36Cldetection efficiency), which compares favorable to other facilities. We will demonstrate that 36Cl measurements, which are competitive to larger tandems, are now possible.

References [1] P. Steier, O. Forstner, R. Golser, W. Kutschera, M. Martschini, S. Merchel,

T. Orlowski, A. Priller, C. Vockenhuber, A. Wallner, Nucl. Instr. Methods Phys. Res. B 268 (2010) 744

[2] T. Orlowski, O. Forstner, R. Golser, W. Kutschera, M. Martschini, S. Merchel, A. Priller, P. Steier, C. Vockenhuber, A. Wallner, Nucl. Instr. Methods Phys. Res. B 268 (2010) 847

[3] H. Schmidt-Böcking, H. Hornung, Z. Physik A286 (1978) 253 [4] L.C. Northcliffe, R.F. Schilling, Nucl. Data Tabl. A7 (1970) 233


A New Cryogenic Target and Microwave Cavity for Hyperfinestructure Spectroscopy of Antiprotonic Helium

O. Massiczek1, S. Friedreich2, B. Juhász2, E. Widmann2 and J. Zmeskal2

1Stefan-Meyer Insitiute for subatomic Physics, Austrian Academy of Sciences, Boltzmanngase 3, 1090 Wien, [email protected] 2Stefan-Meyer Insitiute for subatomic Physics, Austrian Academy of Sciences, Boltzmanngase 3, 1090 Wien

A new cryostat with pulse tube refrigeration and gas-tight microwave cavity with a laser and antiproton window has been designed and built to study the hyperfine structure of antiprotonic Helium-3 and Helium-4. The improvements between this and the old system [1] will be explained. Also the performance of the setup during the 2009 and 2010 beamtimes at the CERN Antiproton Decelerator will be discussed.

References [1] J. Sakaguchi, H. Gilg, R.S. Hayano, T. Ishikawa, K. Suzuki, E. Widmann,

H. Yamaguchi, F. Caspers, J. Eades, M. Hori, D. Barna, D. Horvath, B.

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Juhasz, H.A. Torii, T. Yamazaki “Cryogenic tunable microwave cavity at 13 GHz for hyperfine spectroscopy

of antiprotonic helium“ Nucl. Instrum. Methods in Phys. Research A 533, 598 (2004).


Hyperfine Structure Spectroscopy with Antiprotonic Helium

S. Friedreich1, B. Juhász2, O. Massiczek2 and E. Widmann2

1Stefan-Meyer Institute for subatomic Physics, Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Wien, [email protected] Institute for subatomic Physics, Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Wien

Antiprotonic helium is a neutral exotic atom, consisting of a helium nucleus, an electron and an antiproton. The interactions of the angular momenta and spins of its constituents cause splitting within the principle states. The measured transition frequencies between hyperfine levels can be compared with three-body QED calculations as a test of the theory. Previous measurements have been performed on antiprotonic 4He [1], [2]. Currently a similar transition state is being measured in 3He. Due to the additional coupling of the antiproton orbital angular momentum to the hellion spin, it consists of an octuplet of hyperfine substates instead of a quadruplet. A measurement of this system would lead to a more stringent test of the theory and also address systematic errors therein. A completely new setup has been designed and built for the hyperfine structure measurements of antiprotonic 3He. It will be reported on the test of the new microwave cavities and the first spectroscopy results.

References [1] E. Widmann, J. Eades, T. Ishikawa, J. Sakaguchi, T. Tasaki, H. Yamaguchi,

R.S. Hayano, M. Hori, H.A. Torii, B. Juhász, D. Horváth, Yamazaki, “Hyperfine structure of antiprotonic helium revealed by a laser-microwave-laser resonance method”, Phys. Rev. Lett. 89, 243402, (2002)

[2] T. Pask, D. Barna, A. Dax, R.S. Hayano, M. Hori, D. Horváth, S. Friedreich, B. Juhász, O. Massiczek, N. Ono, A. Sótér, E. Widmann, “Antiproton magnetic moment determined from the HFS of antiprotonic helium”, Phys. Lett. B, 678 (1,6), 55-59 (2009)

[3] V.I. Korobov, Z.-X. Zhong, “Precision spectroscopy of antiprotonic helium”, Phys. Rev. A, 80, 042506, (2009)

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AMS Measurement of the Reaction 35Cl(n, )36Cl and its Relevance to Astrophysics and Nuclear Technology

S. Pavetich1, T. Belgya2, M. Bichler3, I. Dillmann4, O. Forstner1, R. Golser1,F. Käppeler4, Z. Kis2, M. Martschini1, A. Priller1, P. Steier1, G. Steinhauser3,L. Szentmiklosi2 and A. Wallner1

1 VERA Laboratory, Faculty of Physics, University of Vienna, Währinger Str. 17, 1090 Vienna, Austria, [email protected] 2 Department of Nuclear Research, Institute of Isotopes, Hungarian Academy of Sciences, 1525 Budapest, Hungary 3 Atominstitut der Österreichischen Universitäten (ATI), Stadionallee 2, 1020 Vienna, Austria 4 Karlsruhe Institute of Technology (KIT), Postfach 3640, 76021 Karlsruhe, Germany

36Cl is a long-lived radionuclide (t1/2 = 301000 a), which is dominantly produced via the reaction 35Cl(n, )36Cl. The seed nuclei of this reaction, the stable 35Cl, acts as a neutron poison in the nucleosynthesis processes during later burning phases of stars. This makes the reaction important for astrophysical calculations, aiming to reproduce the abundances of elements. Due to the long half-life of 36Cl, the cross section and the production rate of the above reaction are also important for nuclear technology and nuclear waste management. The two main goals of this work are: (i) the production of an independent 36Cl/35Clstandard for accelerator mass spectrometry (AMS); and (ii) the determination of the Maxwellian averaged cross section (MACS) of 35Cl(n, )36Cl at 25 keV using AMS. Approaching the first goal, NaCl pellets were irradiated at the TRIGA Mark II reactor at the ATI in Vienna and at the Budapest research reactor. The neutron flux was monitored via the reference cross section of 197Au(n, )198Au (gold foils attached to and gold powder homogenously mixed into the pellets) and determined by activity measurements on the foils and the pellets. With this data we calculated a 36Cl/35Clratio for the irradiated samples. The AMS measurements on these samples were performed at VERA (Vienna Environmental Research Accelerator), relative to a standard from ETH Zurich. The comparison of the 36Cl/35Cl ratio calculated from the activity measurements and measured ratios by AMS shows a systematic discrepancy of 5%. To determine the neutron capture cross section of 35Cl, AMS measurements were performed on two samples, which were irradiated with neutrons of a Maxwell-Boltzmann energy distribution of 25 keV at the Forschungszentrum Karlsruhe. A preliminary mean value for the cross section is deduced by combining the AMS data and the neutron-fluence. The relevant cross section for nucleosynthesis in stars (MACS) will be calculated by weighting the mean value for the cross section with a Maxwell-Boltzmann energy distribution of 25 keV. The irradiation techniques and the measuring procedure by AMS will be discussed and our new results will be compared with previous measurements of neutron capture on 35Cl.

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HFOLD a Program Package for Calculating MSSM Two-Body Higgs Decays at Full one-Loop Level

W. Frisch1 and H. Eberl2

1Hephy Vienna, [email protected] Vienna, [email protected]

HFOLD (Higgs Full One-Loop Decays) is the first public available program which calculates all MSSM Higgs two-body decays at full one-loop level. The renormalization is done in the DRbar scheme following the SPA convention. The program is easy to use and supports Les Houches in- and output format. We compare the numerical results from HFOLD with some other public available programs. Particular attention is paid to the size of the electroweak corrections.


Using Vienna Tier-2 Grid computing for data analysis of the CMS experiment and for other research projects

N. Hörmann1, D. Liko2 and G. Walzel3

1Institute of High Energy Physics (HEPHY), Nikolsdorfergasse 18, 1050 Wien, Austria, [email protected],3Institute of High Energy Physics (HEPHY), Nikolsdorfergasse 18, 1050 Wien, Austria

In February this year the LHC accelerator at CERN has reached the new center of mass energy of 7 TeV. This will allow particle physicists to complete the current understanding of the Standard Model and to search for new physics like the Higgs boson or supersymmetric particles. The collected huge amount of data from the LHC experiments is being eagerly analyzed by thousands of physicists around the world. Supported by the European Union and other funding agencies, a worldwide computing infrastructure, the Grid, has been established to provide the required resources in terms of computing power and storage capacity. To support the Austrian scientific community, the Austrian Academy of Sciences and the University of Innsbruck, have established a large Tier-2 computing center. Data from the CMS experiment are continuously being transferred to the Institute of High Energy Physics in Vienna and then analyzed by the local analysis team, which has already provided first physics results. This presentation will review the workflow of the data analysis at the Vienna computing center and give a brief overview of the ongoing studies of the first CMS data. Finally we show how researchers from other fields like radiobiology and theoretical physics are using these powerful computing resources.

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Jeremy – A Code for Radiological Characterization of Accelerator Components at CERN

R. Fröschl

CERN DGS RP, CH-1211 Geneve 23, Switzerland, [email protected]

Beam losses are responsible for material activation in components of the CERN accelerator complex. The prediction of the radionuclide inventory of these components represents a crucial task for various reasons. On the one hand, it is important to know the activation levels in order to classify the material as radioactive and devise appropriate handling procedures with respect to maintenance. On the other hand, a detailed radionuclide inventory is also necessary for the elimination of radioactive waste to the final repositories. A specifically-written code, JEREMY, calculates the radionuclide inventory analytically by using the so-called Matrix Method. The calculations involve the use of cross-sections, representative spectra and radiological history. Calculations with JEREMY are virtually instantaneous and can be repeated over a set of input parameters for sensitivity studies. The design and the current status of the code will be presented as well as the planned experimental validation and the first applications.

References [1] Magistris, M., “The matrix method for radiological characterization of

radioactive waste”, Nucl. Instr. and Meth. Phys. Res. B 262 (2), 182-188 (2007)


GENEUS - A Program Designed for Nuclear Data Evaluations

D. Neudecker1, S. Gundacker2, T. Srdinko2, V. Wildpaner2 and H.Leeb2

1Inst. of Atomic and Subatomic Phys., TU Wien, Wiedner Hauptstr. 8, 1040 Wien, [email protected]. of Atomic and Subatomic Phys., TU Wien, Wiedner Hauptstr. 8, 1040 Wien

Nuclear data evaluations merge experimental and theoretical knowledge in order to produce evaluated information which is suitable for the design of novel nuclear technologies and radioactive waste incineration- e.g. accelerator driven system,

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generation IV reactors, fusion reactors. However, for these applications uncertainty information is of utmost importance, especially for energy ranges with scarce experimental information (beyond 20 MeV).

GENEUS (General Nuclear Data Evaluation and Uncertainty System) is a program package which evaluates angle-integrated cross sections for neutron-induced reactions and associated covariance matrices [1]. The program starts out from model cross sections provided by the nuclear model code TALYS-1.0[2] and prior covariance matrices containing parameter uncertainties and model defects. The former account for the limited knowledge of the parameters of the nuclear model employed and the latter for deficiencies of the model with regard to actually measured values. In few update steps, experimental information, consisting of cross sections as well as covariance matrices is added via the linearized Bayesian Update. The output is given in the ENDF-format, the standard format for nuclear data libraries. The method is illustrated by means of evaluations on Pb-208 and Mn-55. Work partly supported by the EURATOM project IP_EUROTRANS and the F4E-project NUDATA_FILES. The views and opinions expressed herein do not reflect necessarily those of the European Commission.

References [1] Leeb H., Neudecker D. and Srdinko Th., ”Consistent Procedure for Nuclear

Data Evaluation Based on Modeling”, Nucl. Data Sheets 109 2762 (2008) [2] Koning A. J., Hilaire S. and Duijvestijn M. C., “TALYS-1.0”, Proc. of the

Internat. Conf. on Nucl. Data for Sci. and Tech.: ND2007, Nice, France, April 22-27, 2007, EDP Sciences, 211 (2008)


Silicon Photomultiplier for Subatomic Physics Experiments - Performance Studies at SMI

G.S.M. Ahmed1,2, P. Bühler1, J. Marton1 and K. Suzuki1

1Stefan Meyer Institute, Austrian Academy of Sciences, Vienna, Austria [email protected] 2Al-Azhar University, Faculty of Science, Physics Department, Cairo, Egypt

The detection of a low-intensity light photon flux is one of the key processes in experimental physics, from solid-state physics to high-energy physics and astroparticle physics. The energy of the particles to be observed by detectors is partly converted into visible photons which then are detected by appropriate sensors. Silicon Photomultipliers (SiPMs) are semiconductor devices consisting of many photon microcounters positioned on a common Silicon substrate. Each single microcounter (avalanche photo diode, APD) is working in the Geiger-mode. SiPMs

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have numerous advantages compared to other photodetectors (fast response, high gain, photon counting capability, compactness, insensitivity to magnetic fields, low voltage operation) and represent a promising solution for the light detection and providing the potential to replace classical photomultipliers (PMT) in many applications, such as scintillating fiber readout, imaging Cherenkov counter [3-4]. In our institute we are characterizing SiPMs from different manufacturers, in order to find out the optimum conditions for a given application. Measurements of dark current, dark count rate and cross-talk of this device have been presented elsewhere [1-2]. One of the most important features of SiPMs is the capability of ultrafast timing (picoseconds range). Here we are presenting our latest results of the SiPMs timing performance at SMI. Furthermore, main SiPMs features and two examples of applications are described.

Acknowledgements This work is partly supported by INTAS (project 05-1000008-8114) and Hadronphysics2 (project 227431). One of us (G.A.) acknowledges the support by the Egyptian Ministry of higher education.

References [1] G.S.M. Ahmed., “Studies of GM-APD (SiPM) Properties”, Journal of

Instrumentation 4, (P09004), (2009) [2] D. Renker., “Geiger-mode avalanche photodiodes, history, properties and

problems”, Nuclear Instruments and Methods in Physics Research A 567,(48–56) (2006)

[3] G.S.M. Ahmed., “Study of timing performance of Silicon Photomultiplier and application for a Cherenkov detector”, Nuclear Instruments and Methods in Physics Research A (in press), arXiv:1004.4144

[4] K. Suzuki., “Development of SciFi/CheFi detector with SiPM readout”, Nuclear Instruments and Methods in Physics Research A 620, (75-77) (2009)


Belle II Silicon Vertex Detector: Mechanics and Cooling

I. Gfall1, T. Bergauer1, M. Friedl1, C. Irmler1, M. Valentan1

1 Institute of High Energy Physics, Nikolsdorfergasse 18, A-1050 Vienna, Austria [email protected]

The Belle experiment at KEK in Tsukuba, Japan is the only operating B-factory today and its precision measurements have led to the justification of the Nobel Prize earned by Kobayashi and Maskawa in 2008. In June 2010, the machine was brought to a halt for a promising future, namely an upgrade to be completed until 2014. By this time all important components are to be exchanged for an

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unprecedented performance boost of the accelerator (KEKB) and the Belle Detector. With this upgrade, KEKB will beat its own luminosity world record (2.11 x 1034 cm-2s-1) by a factor of 40 [1]. The Belle Detector consists of several sub detectors. One of those detectors is the Silicon Vertex Detector (SVD). The SVD is located close to the beam pipe to allow high precision track finding. The proximity to the beam pipe and the high beam currents result in a very high level of background radiation for the SVD. To cope with the new challenges of higher backgrounds and the need for even higher precision measurements, the Origami sensor design was developed. This design comes with a great performance increase that is fit to cope with the new Belle II requirements.Nevertheless it is important to implement a light and yet stable mechanical construction that can withstand the radiation and temperature conditions such that the detectors capabilities are not compromised. In order to push the performance further, a cutting edge cooling system is under development to further improve the signal to noise ratio. This cooling system will operate with CO2 to allow highly efficient electronics cooling with a minimal cooling tube thickness to avoid additional material inside the acceptance region.

References [1] M. Friedl,”Upgrade of the Belle Silicon Vertex Detector”, 1st international

conference on Technology and Instrumentation in Particle Physics proceedings, article in press in NIM A


Ground Motion Mitigation in the Main Linac of CLIC

J. Pfingstner1, D. Schulte2 and M. Hofbaur3

1PhD student at Graz University of Technology working at CERN, [email protected] Organization for Nuclear Research (CERN) 3Private University UMIT Hall/Tyrol, Austria

The future linear collider CLIC (Compact Linear Collider) is CERN’s propose for a successor of the LHC (Large Hadron Collider). The design of CLIC requires ultra-low particle beam emittances, which makes the accelerator very sensitive to ground motion. Without countermeasure, the beam quality would be already unacceptable after a few seconds. In our work we present a feedback algorithm, which mitigates the parasitic effects of ground motion in the main linac of CLIC efficiently. We use an adaptive controller, which is composed of two parts: a system identification unit and a SVD control algorithm. The system identification unit calculates on-line estimates of the time-changing accelerator behaviour. This precise model, which can adapt to system changes, is used by the control algorithm. If the system identification unit would not

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be used, drifting accelerator parameter would cause a mismatch between the real accelerator behaviour and the model used by the controller, which would result in a poor controller performance. Standard system identification algorithms cannot be used in an accelerator environment. The indispensable system excitation cause a not tolerable emittance growth, if it is applied thoughtless. Instead a special excitation scheme consisting of interleaved beam bumps was implemented, which keeps the emittance growth at an acceptable level. However, this special excitation has the disadvantage that not the complete system can be identified anymore. To still get an all over model of the system, we use the identification data and interpolate them with the help of a beam oscillation amplitude model, derived for the main linac of CLIC. The control algorithm uses the identified system data, which are the orbit response matrix R. With the help of the SVD decomposition of R, a very efficient filter can be created. This filter reconstructs the ground motion components, which are causing the majority of the emittance growth. At the same time the filter strongly suppresses the measurement noise of the sensors. The described adaptive control algorithm was simulated with the help of the particle tracking code PLACET. The system identification algorithm is capable of identifying system changes in a step- and drift-like manner. A learning coefficient can be used to balance between noise suppression and adaption speed. In a typical configuration, 4.1 sec. are needed to recover from 90% of a step-like model change. The steady-state error is about 13%. This error comes from measurement noise and the limited accuracy of the amplitude model. The SVD controller succeeds in keeping the emittance growth at a level of about 0.1 nm rad. It also keeps the pulse-to-pulse jitter at a very low level, by efficiently suppressing measurement noise. Concluding, we would like to point out that the presented adaptive control scheme is capable of suppressing the ground motion effects in the main linac of CLIC efficiently. Additional advantages of the scheme are reduction of down-time to measure R in a traditional way and the possibility of carry out system diagnostics and error detection.

References Sery, A. and Napoly, O., “Influence of ground motion on the time evolution of beams

in linear colliders”, Phys. Rev. E 53, 5323-5346 (1996). Steinhagen, R. J., “LHC Beam Stability and Feedback Control”, PhD thesis,

Technische Hochschule Aachen (2007)

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GEM Detector Development for Hadron-Physics Experiments

P. Müllner1,a, und J. Zmeskal1

1 Stefan Meyer Institut für subatomare Physik Boltzmanngasse 3, 1090 Wien a [email protected]

The next experiments in hadron-physics aim at studying rare processes with improved sensitivity (e.g. PANDA) [1]. The technical requirements for these experiments include fast detectors for charged particles with large acceptance and excellent tracking capabilities. With the GEM (Gas Electron Multiplier) technology it is possible to build detectors, which meet the demands for such experiments. The GEM technology bases on a thin polymide foil with a copper cladding on both sides [2]. A large number of microholes are chemically etched into this foil. By applying a voltage difference of several hundred volts, an electrical field of several kV/cm is produced inside the holes. Therefore the holes acts as a multiplication channel for electrons and as a trap for positive charged particles. A GEM detector is a gas detector with one or more GEM foils mounted between the cathode and anode. The SMI (Stefan Meyer Institute for subatomic physics) in Vienna build a triple GEM detector with an active area of 50x50 mm2, which was tested with PIXE (Proton Induced X-ray Emission) at the VERA (Vienna Environmental Research Accelerator). The location dependence of the intrinsic efficiency across the detection area was examined. Due to the collected experience from the results of these test, the SMI build now a new triple GEM detector prototype with a larger active area of 100x100 mm2 and improved readout electronics.

References [1] Schmitt, L., “The PANDA detector at FAIR”, Nuclear Instruments and

Methods in Physics Research A 581, 542-544 (2007) [2] Sauli, F., “GEM: A new concept for electron amplification in gas detectors”,

Nuclear Instruments and Methods in Physics Research A 386, 531-534 (1997)

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8.5 FKP / NESY – Festkörperphysik / Physik an Neutronen- und Synchrotronstrahlungsquellen

Donnerstag - Thursday 9 September 2010 / HS 403Fachausschuss Festkörperphysik –

Scientific Committee Solid State Physics (FKP)

Fachausschuss Forschung mit Neutronen und Synchrotronstrahlung -

Scientific Committee Research with Neutrons and Synchrotron Radiation (NESY)

Parallel Session FKP - NESY

Zeit Time



9:00 – 9:40 Keynote:

Christian Pfleiderer (TU München)

Versatile neutron scattering techniques with ultra-high resolution

9:40 – 9:55 Michael Benedikt (CERN) Status of the MedAustron project

9:55 – 10:10 Heinz Amenitsch (ÖAW) Real time SAXS analysis on nanosystems

10:10 – 10:25 Maxim Erko (MU Leoben) Water freezing in nanopores

10:25 – 10:40 Michael Leitner (Univ. Wien)

Studying atomic diffusion by coherent synchrotron radiation

11:40 – 11:55 Benedetta Marmiroli (ÖAW)

Sub 100 μs studies of fast chemical and biological reactions using a free-jet

micromixer

11:00 - 11:30 Pause - Coffee Break

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Donnerstag - Thursday 9 September 2010 / HS 403Fachausschuss Festkörperphysik - Scientific Committee

Solid State Physics (FKP) Fachausschuss Forschung mit Neutronen und Synchrotronstrahlung

Scientific Committee Research with Neutrons and Synchrotron Radiation (NESY)

Parallel Session FKP - NESY

Zeit Time



13:30 – 14:00 Keynote:

Heinz Krenn (Univ. Graz)

How to stabilize the magnetism of ultrasmall nanomagnets ?

14:00 – 14:15 Rainer T. Lechner(MU Leoben)

Magnetic properties of epitaxial GeMnTe determined by crystal structure

14:15 – 14:30 Andreas

Buchsbaum (TU Wien)

Magnetic Properties of Co Clusters on Alumina on Ni3Al(111)

14:30 – 14:45 Kashif Nadeem(Univ. Graz)

Magnetic studies of fine maghemite nanoparticles prepared by microwave plasma

synthesis

14:45 – 15:10 Gang Chen (Univ. Linz)

Damascene process for controlled positioning of magnetic colloidal nanocrystals

15:10 – 15:30 Matthias

Wegscheider (Univ. Linz)

Ferromagnetic resonance studies on epitaxial Fe and Fe3Si films on GaAs (001)


15:50 - 16:20 Thomas Pichler(Univ. Wien)

Tailoring carbon nanostructures: Unravelling the electronic properties of

low-dimensional quantum solids

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16:20 - 16:35 David Geist (Univ. Wien)

Nanocrystallization by heating of amorphous Zr3Al made by repeated cold rolling

16:35 - 16:50 Florian Libisch (TU Wien)

AT&S Prize Lecture: Simulation of coherent, large-scale

nanostructures

16:50 - 17:05 Armin Moser (TU Graz)

Organic dielectrics influence the crystallographic structure of pentacene thin

films

17:05 - 17:20 Daniel Primetzhofer

Anton Paar Prize Lecture: Electronic Interactions of Slow Ions

17:20 - 17:35 Christoph Uiberacker

(MU Leoben)

Current conservation in nonequilibrium networks

17:35 - 18:00 Jahreshauptversammlung des

Fachausschusses FKP FKP Annual General Assembly


Fachausschusses NESY NESY Annual General Assembly

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Freitag - Friday 10 September 2010 / HS 403Fachausschuss Festkörperphysik - Scientific Committee

Solid State Physics (FKP) Fachausschuss Forschung mit Neutronen und Synchrotronstrahlung

-Scientific Committee Research with Neutrons and

Synchrotron Radiation (NESY) Parallel Session FKP - NESY

Zeit Time



9:15 - 9:45 Keynote:

Aaron M. Andrews (TU Wien)

InGaAs/GaAsSb/InP Material System for MIR and THz Quantum Cascade Lasers

9:45 - 10:00 Hermann Detz (TU Wien)

Ring cavity induced performance enhancement in mid-infrared and terahertz

quantum cascade lasers

10:00 - 10:15 Bernhard Mandl (Univ. Linz) Au – free growth of InAs nanowires

10:15 - 10:30 Thomas Moldaschl(TU Wien)

Two-photon excitation of InAs / GaAs quantum dots

10:30 - 10:45 Moritz Brehm (Univ. Linz)

Giant Ge surface diffusion length and stable island sizes during Stranski-Krastanow

nucleation of SiGe/Si(001) islands

10:45 - 11:00 Rainer T. Lechner(MU Leoben)

X-ray scattering studies of magnetic CoFeO nano-cubes

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FKP-NESY-1: Grüner Hörsaal, Do, 9 Sept, 09:00 Uhr

Versatile Neutron Scattering Techniques with Ultra-high Resolution

C. Pfleiderer

Physik-Department, Technische Universität München, D-85748 Garching, Germany E-mail: [email protected]

Neutron scattering has a long history as a unique experimental tool in the exploration of condensed matter systems. The development of neutron resonance spin flippers, invented over twenty years ago in Munich, has recently paved the way to a new generation of versatile neutron scattering techniques with ultra-high resolution. Following a basic introduction I will illustrate the opportunities for the scientific community referring to examples in the field of emergent phenomena. This includes the search for genuine non-Fermi liquid phases, the identification of enigmatic forms of hidden order and, last but not least, the origin of unconventional superconductivity.


Status of the MedAustron Project

M. Benedikt

CERN, CH-1211 Geneva 23, [email protected]

MedAustron is a planned centre for hadron therapy and diagnosis in Austria. The centre is based on a synchrotron which will deliver beams of protons up to 800 MeV/c and carbon ions up to 400 MeV/c per nucleon with intensities of 1010

protons/s and 4.108 ions/s, respectively. Although the accelerator layout is primarily dedicated to clinical application, dedicated beam time for research applications in the domain of medical radiation physics, radiation biology and experimental physics is also foreseen. Layout requirements for the medical and research applications are established. Civil engineering design is conducted in Austria, where the accelerator complex is designed in collaboration with CERN. A mandatory Environmental Impact Assessment (Umweltverträglichkeitsprüfung) is currently for review with the Austrian Authorities. Following the EIA approval expected at the end 2010, ground-breaking is scheduled for early 2011. First beams for application are scheduled for 2014. This presentation will summarize the up-to-date layout of the MedAustron facility, status of the project and outlook on usability for the different applications with emphasize on research activities for experimental physics.

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Real Time SAXS Analysis on Nanosystems

H. Amenitsch1, B. Marmiroli1, B. Sartori1, F. Cacho-Nerin1, K. Jungnikl1,and M. Rappolt1

1Institute of Biophysics and Nanosystems Research, Austrian Academy of Sciences, Schmiedlstr. 6, A-8042 Graz, Austria, E-mail: [email protected]

Small Angle X-ray Scattering (SAXS) has developed as a powerful working horse in almost all synchrotrons in the world. Its fundamental strength is the capability of in situ investigations for all states of matter - gas, liquid and solid – as well as probing materials in bulk, surface sensitive (grazing incidence SAXS) or with high local spatial resolution (scanning SAXS).

This presentation should summarize the current state of the art investigating self-assembly processes i.e. watching molecules in situ to form nano(bio)materials or the in situ response of supramolecular structures to physical/chemical parameter changes as temperature, stretch etc. Some highlights of the current research covering the fields of life sciences till nanomaterials will be discussed and will include the above mentioned application areas of the SAXS and GISAXS technique. The examples will range - to name just a few – from self-assembly of nanotubes in form of helical ribbons [1], in situ study of the formation of mesoporous materials on surfaces as well as in solution [2], to self-assembly of nanoparticles [3,4].

At the same time, for advanced studies on nanomaterials, the integration of in situ chemical and physical perturbation technicques into the experimental set-up is a prerequisite. Some sophisticated instrumental developments like ultrafast mixers with μs-resolution [5,6], in situ aerosol reactors [7], or optical tweezers [8] are presented with adequate examples.

References [1] C.V. Teixeira, et al., “Formfactor of a N-layered helical tape and its

application to nanotubeformation of Hexa-peri-hexabenzocoronene based molecules “, J. Appl. Cryst (2010) in press.

[2] D. Grosso, et al., “Periodically ordered nanoscale islands and mesoporous films composed of nanocrystalline multimetallic oxides”, Nature Materials 3 (2004) 787.

[3] R. Viswanatha, et al., “Growth mechanism of cadmium sulfide nanocrystals ”J. Phys. Chem. Let. 1 (2010) 308.

[4] F.Toma, et al., “Efficient water oxidation at carbon nanotube–polyoxometallate electrocatalytic interfaces“, Nature Chemistry, (2010), in press.

[5] B. Marmiroli, et al., “Free jet micromixer to study fast chemical reactions by small angle X-ray scattering”, Lab on Chip. 9 (2009) 2063.

[6] W. Schmidt, et al., ”Accessing Ultrashort Reaction Times in Particle Formation with SAXS Experiments: ZnS Precipitation on the Microsecond

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Time Scale”, JACS (2010) 10.1021/ja101519z. [7] I. Shyjumon, et al., “Novel in situ setup to study the formation of

nanoparticles in the gas phase by small angle x-ray scattering”, Rev. Sci. Instr. 79, (2008) 43905.

[8] D.Cojoc, et al., ”Scanning x-ray microdiffraction of optically manipulated liposomes”, APL 91, (2008) 234107.


Water Freezing in Nanopores

M. Erko1, D. Wallacher2, A. Höll3 and O. Paris4

1 Institute of Physics, University of Leoben, 8700 Leoben, Austria. [email protected] Helmholtz Zentrum Berlin für Materialien und Energie, 14109 Berlin, Germany. 3 Helmholtz Zentrum Berlin für Materialien und Energie, 14109 Berlin, Germany. 4 Institute of Physics, University of Leoben, 8700 Leoben, Austria.

The structure and dynamics of supercooled liquid water and of amorphous ice is a very active area of current research [1, 2]. Confinement induces new phenomena such as melting point suppression, and in some cases, water seems even not to freeze at all, as shown in recent differential scanning calorimetry (DSC) measurements [3]. Micelle-templated porous silica materials, such as SBA-15 and MCM-41 [4] represent ideal model systems for studying water in nano-confinement. The pores of these materials are perfectly ordered on a two-dimensional hexagonal lattice with lattice parameter of a few Nanometers, making these materials ideal for investigations with small-angle X-ray (SAXS) and neutron (SANS) scattering methods [5, 6]. We performed Synchrotron-SAXS and SANS measurement on water-filled MCM-41 and SBA-15 porous materials with pore diameters ranging from 2 nm – 9 nm. The advantages of the two complementary scattering techniques, SAXS and SANS are ideally applied to our system. The high brilliance synchrotron radiation makes strain effects in the order of 10^-3 resolvable. The phase contrast variation in neutron scattering allows a detailed investigation of density change of water by using a proper H2O/D2O.Two phenomena could be observed during freezing and melting of confined water. First, the water density change during phase transformation results in change of the scattering contrast and therefore changes the scattering intensity. Second, the strain-induced contraction and expansion of the pore lattice during water phase transformation leads to a shift of the Bragg-Peak position [7]. Both effects are observed for water in large pores exactly at the phase transition temperatures predicted by DSC. Moreover, these effects are present even for water confined in pores below 2,5 nm where water is assumed not to freeze. Additionally, we performed cooling and heating cycles on samples with different pore filling fractions. Different number of the few water layers on pore walls show different freezing and

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melting behaviour which is discussed together with the results from fully-filled pores with different diameters.

References [1] O. Mishima, H. E. Stanley, Nature 396, 329-335 (1998). [2] P. G. Debenedetti, H. E. Stanley, Physics Today 56, 40-46 (2003). [3] G. H. Findenegg, S. Jähnert, D. Akcakayiran, A. Schreiber, ChemPhysChem

9, 2651-2659 (2008). [4] D. Zhao, J. Feng, Q. Huo, N. Melosh, G.H. Fredrickson, B.F.

Chmelka, G.D. Stucky, Science 279, 548-52 (1998). [5] M. Erko, D. Wallacher, A. Brandt, O. Paris, Journal of Applied

Chrystallography 43, 1-7 (2010). [6] G.H. Findenegg, S. Jahnert, D. Müter, J. Prass, O. Paris, Phys. Chem.

Chem. Phys. 12, 7211-7220 (2010). [7] J. Prass, D. Mueter, P. Fratzl, O. Paris, Applied Physics Letters 95, 083121

(2009).


Studying Atomic Diffusion by Coherent Synchrotron Radiation

M. Leitner1, B. Sepiol, F. Gröstlinger, and G. Vogl

Fakultät für Physik, Universität Wien, Strudlhofgasse 4, 1090 Wien E-Mail: [email protected]

The static structure of solids on the atomic scale is nowadays very well known. Knowledge about dynamics, i.e. how this structure evolves via jumps of the atoms, is much scarcer, however, and is only rarely based on direct experimental investigations.

X-ray Photon Correlation Spectroscopy (XPCS) is an upcoming method for studying the dynamics of matter on small scales. It consists in scattering coherent radiation at the sample and analyzing the temporal fluctuations of the scattered intensity.

Recently we have succeeded in applying this method for the first time to dynamics on the atomic scale [1]. I will present our results on diffusion in the system Cu-Au, specifically the influence of short-range order on the atomic jumps. I will also give preliminary results on the dynamics in a metallic glass and in B2-ordered NiAl.

References [1] M. Leitner, B. Sepiol, L.-M. Stadler, B. Pfau, and G. Vogl, “Atomic diffusion

studied with coherent X-rays” Nature Mat. 8, 717 (2009).

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Sub 100 μS Studies oF Fast Chemical and Biological Reactions Using a Free- Jet Micromixer

B. Marmiroli1, F. Cacho-Nerin1, B. Sartori1, G. Grenci2, J. Perez3, P. Laggner1

and H. Amenitsch1

1Institute for Biophysics and Nanosystem Research, Austrian Academy of Sciences, Schmiedlstrasse 6, Graz, 8042, Austria 2IOM - CNR, SS 14 km 163.5, 34012 Basovizza (TS), Italy 3SWING beamline - Synchrotron SOLEIL, L'Orme des Merisiers BP 48 Saint-Aubin, Gif sur Yvette, 91192, France

Short time-scales are fundamental for gaining insight in fast chemical and biological reactions like the nucleation and growth of nanoparticles or the conformational changes of proteins. In the present communication we describe first the design, the fabrication process, and the system engineering of a microfluidic mixer aimed to studies of fast chemical and biological reactions with a time resolution lower than 100 μs [1]. The mixer is based on hydrodynamic focusing. It works in the laminar regime, and mixing occurs only by diffusion that can be predicted and controlled. The mixing is completed inside the device before the nozzle, and a free liquid jet in air exits from the device. The time evolution of the reaction is separated spatially in the steady state flow along the liquid jet exiting from the device. Measuring the signal form the jet at different distances from the nozzle exit corresponds to measuring the reaction at different times from the beginning of the mixing. The geometry and dimensions of the device have been optimized by Finite Element Analysis, and are stringent: outlet channel 500 μm long and 10 μm wide, and exit nozzle 8 μm wide in order to produce a stable jet. The channels depth is 60 μm. Even if the device has been optimized for synchrotron SAXS measurements [2], the choice of a free jet as observation region overcomes the problem of the material selection for the microfluidic chamber. This enables to use the same device with different investigation techniques (i.e Light Scattering and Raman Spectroscopy). The device usually works with a total flow rate of 300 μl/min, leading to a jet speed of 13 m/s, and to a mixing time of 45 μs. Anyway it can bear flow rates larger than 1 ml/min, corresponding to a nominal time resolution of 26ns/μm. The micromixer can be used to study a wide variety of fast chemical and biological reactions by adequately tuning the operating conditions. The maximum pressure inside the device is less than the denaturation limit for proteins. The shear rate is not sufficient to destabilize a typical small protein of ~100 amino acids in water, but it could have influence on bigger proteins or when using viscous solvents. Therefore, the possibility to use the device with biological reagents must be evaluated for each specific case. Latest results of SAXS characterization of the jet itself, and of the early stages of nucleation and growth of nanoparticles will be presented.

References [1] Marmiroli, B. et al., “Free jet micromixer to study fast chemical reactions by

small angle X-ray scattering”, Lab on Chip 9, 2063-2069 (2009)

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[2] Marmiroli, B. et al., “Experimental set-up for time resolved small angle X-ray scattering studies of nanoparticles formation using a free -jet micromixer “,Nuclear Instruments and Methods in Physics Research B 268, 329-333 (2010)


How to Stabilize the Magnetism of Ultrasmall Nanomagnets?

H. Krenn and K. Nadeem

Institut für Physik Karl-Franzens-Universität Graz, Universitätsplatz 5, A-8010 Graz, Austria

Magnetic nanoparticles play an outstanding role in advanced high-density magnetic data storage, in magnetic fluids, in paleo- and rock-magnetism and as amplifiers for magnetic resonance imaging. As the sizes of monodomain particles are smaller than few nanometers the so-called superparamagnetic limit is reached - a critical threshold - beyond which a stable magnetic state cannot be maintained. Thermal agitation erases the stored magnetism due to large fluctuations. Thus the question how to overrule such a limitation is of fundamental interest not only for increasing the bit density of storage media, but is also related to the role of magnetic phase transitions within and around small nanomagnets. The well-known Nèel-Brown relaxation model of isolated particles is the prominent starting point to study the enduration of “blocked” magnetized particles. However, magnetic relaxation is not solely explainable by magnetic blocking mediated by magnetocrystalline and shape anisotropy as it is manifested by a plenty of recent publications. Disorder and frustration on the surface of nanoparticles become dominant as the surface to volume ratio increases, therefore exchange anisotropy, exchange bias, spin-glass freezing and interparticle interactions must be taken into account. Most of these phenomena stiffen the magnetic moment orientation of nanomagnets although the total magnetic moment is partly diminished. Material parameters, the mutual interactions of the core/shell structure and dipolar coupling between particles provide a rich field for studying thermal activation, scaling laws and frustration phenomena of such complex arrangements of nanoparticles (“superspin-glass”). We investigate powders and mildly compacted samples of ferrite (NiFe2O4,CoFe2O4, -Fe2O3) and antiferromagnetic particles (NiO) particles to follow the route from isolated superparamagnetic particles toward interacting dense nanomagnets. The aim is a tutorial-like presentation of this challenging new field of reduced dimensional magnetism with an outlook for future applications in materials science and data storage.

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Magnetic Properties of Epitaxial GeMnTe Determined by Crystal Structure

R.T. Lechner1,2, G. Springholz1, M. Hassan1, H. Groiss1, R. Kirchschlager1, J. Stangl1, N. Hrauda1, and G. Bauer1

1Institut für Physik, Montanuniv. Leoben, Franz-Josef-Straße 18, A-8700 Leoben, Austria 2Institut für Halbleiter- und Festkörperphysik, Johannes Kepler Universität Linz, A-4040 Linz

A promising candidate for a ferromagnetic semiconductor (FM) is IV-VI Ge1-xMnxTe with Curie temperatures as high as 190 K [1] and a solubility limit for Mn of about 90%. The crystalline structure and hence the ferromagnetic properties of MBE grown samples, however, depend strongly on the Mn concentration as well as on the growth conditions. The samples were grown by molecular beam epitaxy with Mn contents ranging from xMn = 0 to 100%. The growth conditions were adjusted to avoid the formation of prezipitates [2]. The crystal structure of Ge1-xMnxTe changes as a function of composition due to the fact that pure GeTe is rhombohedrally distorted, while pure MnTe crystallizes predominantly in the hexagonal NiAs structure. In the present work, the structure-magnetic properties relationship of Ge1-

xMnxTe was studied systematically as a function of Mn content by x-ray diffraction (XRD) demonstrating a switching of the magnetic easy axes from out-of-plane to in-plane direction at a certain Mn content measured by SQUID magnetometry. This is explained by the structural phase transitions occurring in these compound. For xMnabove 50%, however, crystallographic phase separation between antiferromagnetic MnTe and FM GeMnTe is revealed by synchrotron XRD, resulting in magnetic exchange coupling effects [3].

References [1] Y. Fukuma, H. Asada, S. Miyawaki, T. Koyanagi, S. Senba, K. Goto, and H.

Sato, Carrier-induced ferromagnetism in Ge0.92Mn0.08Te epilayers with a Curie temperature up to 190 K, Appl. Phys. Lett. 93, 252502 (2008)

[2] R.T. Lechner, V. Holy, S. Ahlers, A. Navarro-Quezada, D. Bougeard, J.Stangl, A. Trampert and G. Bauer, Selfassembled Mn5Ge3 nanomagnets close to the surface and deep inside a Ge1-xMnx epilayer, Appl. Phys. Lett.95, 023102 (2009)

[3] R. T. Lechner, G. Springholz, M. Hassan, H. Groiss, R. Kirchschlager, J. Stangl, N. Hrauda, and G. Bauer, Phase separation and exchange biasing in the ferromagnetic IV-VI semiconductor Ge1 xMnxTe, Appl. Phys. Lett. 97,023101 (2010)

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Magnetic Properties of Co Clusters on Alumina on Ni3Al(111)

A. Buchsbaum1, Pardeep K. Thakur2, A. Preobrajenski3, E. Lundgren4,M. De Santis5, H. C.N. Tolentino5, M. Schmid1 and P. Varga1

1Institut für angewandte Physik, Technische Universität Wien, Österreich E-mail: [email protected], ESRF, Grenoble, France 3D1011, MAX-lab, Lund, Sweden 4Division of Synchrotron Radiation Research, Lund Universitity, Sweden 5 Institut Neel, CNRS & UJF, Grenoble, France

The structure of the 0.5 nm thick oxide film on Ni3Al(111) exhibits holes reaching down to the metal substrate at the corners of the ( 67 67 )R12.2° unit cell. Pd atoms trapped in these corner holes create metallic nucleation sites where Co clusters can nucleate and form a well-ordered hexagonal arrangement on the oxide nanomesh [1]. The crystal structure of these Co clusters has been well characterized by scanning tunneling microscopy (STM), surface x-ray diffraction (SXRD) and grazing-incidence small-angle x-ray scattering (GISAXS) [2]. They show random stacking of closed packed Co planes parallel to the substrate surface. Magnetic properties of Co clusters with 350 atoms/cluster have been investigated by x-ray magnetic circular dichroism (XMCD) assisted by STM. This technique allowed us to measure the orbital and spin contribution to the magnetic moment per Fe or Co atom, as well as magnetization curves down to temperatures of 7 K and up to fields of 5 T and correlate the measured magnetic properties to the structure of the clusters. The Co clusters are super-paramagnetic down to 7K and show bulk like magnetic moments of 2 B. From fitting the magnetization curves the magnetic anisotropy energy (MAE) and the direction of the easy axis can be determined. The MAE of the Co clusters is enhanced by a factor of 4 compared to hcp bulk Co and the easy axis is not perpendicular to the surface but tilted. The magnetization curves also suggest magnetic coupling to the substrate, which depends on the number of Pd atoms in the corner hole below the clusters.

References [1] M. Schmid, G. Kresse, A. Buchsbaum, E. Napetschnig, S. Gritschneder,

M. Reichling, P. Varga, Phys. Rev. Lett. 99, 196104-4 (2007). [2] A. Buchsbaum, M. De Santis, H. C.N. Tolentino, M. Schmid, P. Varga,Phys.

Rev. B 81 115420 (2009)

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Magnetic Studies of Fine Maghemite Nanoparticles Prepared by Microwave Plasma Synthesis

K. Nadeem1, H. Krenn1, T. Traussing2, R. Würschum2, and D. V. Szabó3

1 Institute of Physics, Karl-Franzens University Graz, Universitätsplatz 5, A-8010 Graz, Austria, e-mail: [email protected] Institute of Materials Physics, University of Technology Graz, A-8010 Graz, Austria 3 Institute for Materials Research III, Karlsruhe Institute for Technology (KIT), 76021 Karlsruhe, Germany

Magnetic properties of maghemite nanoparticles (5nm) (prepared by microwave plasma synthesis) have been investigated by SQUID-magnetometry. Fine maghemite nanoparticles consist of magnetically aligned core and of disordered surface spins [1]. Disordered and frustrated surface spins give pinning effects and spin-glass freezing at low temperatures [2]. Zero field cooled / field cooled (ZFC/FC) magnetic measurements show magnetic blocking at 75 K. A model for non-interacting nanoparticles have been simulated to reproduce the experimental ZFC/FC curves and to calculate effective anisotropy. Effective anisotropy calculated from the model is larger than the bulk value due to increased surface anisotropy. Frequency dependent AC susceptibility measurements in the frequency range (0.1-1000 Hz) have shown an increase of blocking temperature with increasing frequency. A model of AC susceptibility for non-interacting nanoparticles has been developed to investigate the shift of blocking temperature within a decade of frequency. Simulation of the AC susceptibility model produce large shift in blocking temperature in the frequency range (0.1-1000 Hz). The large value of effective anisotropy from ZFC/ FC model and discrepancy in the AC susceptibility experiment and simulation signify the existence of freezing effects at low temperature on the surface of maghemite nanoparticles. Spin glass freezing on the surface of nanoparticles is a possible mechanism to overcome the superparamagnetic limit which commonly erases the magnetic memory of nanomagnets.

References

[1] R. H. Kodama and A. E. Berkowitz, “Atomic-scale magnetic modeling of oxide nanoparticles”, Physical Review B, 59, 6321-6336 (1999)

[2] B.Martinez, X. Obradors, LI. Balcells, A. Rouanet, and C. Monty, “Low temperature surface spin-glass transition in -Fe2O3 nanoparticles”, Physical review letters, 80, 181-184 (1998)

The authors thank the Austrian national funds for granting the network projects (NFN) S10407-N16 and S10405-N16.

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Damascene Process for Controlled Positioning of Magnetic Colloidal Nanocrystals

G. Chen,1 M. I. Bodnarchuk, M. V. Kovalenko, G. Springholz, W. Heiss, W. Jantsch

Institute of Semiconductor and Solid State Physics, Linz University, Altenbergerstr. 69, A-4040 Linz, Austria

Potential applications of nanocrystals have been recently discussed in diverse fields ranging e.g. from biomedical, plasmonic, photonic, data storage devices, to Lab-on-a-chip concepts, nanocrystals. Significant progress has been achieved in the synthesis of magnetic NCs having well-defined compositions, shapes, structures and sizes. Meanwhile one major challenging issue remains, namely, to produce assemblies of colloidal NCs on well-controlled sites, which is essential to enable separate identification and addressability for single nanoparticle units. In this letter, we report a straight-forward approach for large scale nano-fabrication with high accuracy following the same strategy as the well-established Damascene process in integrated circuit (IC) manufacturing. In the latter, metal interconnects are produced by depositing a thin Cu film on pre-patterned Si wafers and constriction of the Cu film to connecting lines is achieved via a chemical-mechanical back polishing. In our work, the basic idea of this technique is utilized for controlled positioning of NCs by means of deposition on a pre-patterned template, and subsequent NC removal by polishing. The present work demonstrates the potential of such techniques to prepare assemblies of ordered NCs with a size down to 18 nm at low cost and great convenience. Another advantage of this approach is the absence of suspensions or any other solvent during the final processing step, which is an advantage in respect to environment-friendly production. This method allows arranging specific numbers of NCs down to single ones per pit. The structures produced were characterized by scanning electron microscopy (SEM), atomic force- as well as magnetic force microscopy (AFM; MFM) at room temperature.


Ferromagnetic Resonance Studies on Epitaxial Fe and Fe3SiFilms on GaAs (001)

M. Wegscheider, G. Käferböck, C. Gusenbauer, T. Ashraf, R. Koch and W. Jantsch

Institute of Semiconductor / Solid State Physics, Johannes Kepler University, Linz, Austria, [email protected]

1 Corresponding Author: email: [email protected]

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A future spin-based electronics relies on easily implementable semi-conductor/ferromagnet junctions. For instance, the realization of a magnetic logic based on magneto resistive elements [1] or the efficient spin injection into a semiconductor [2-4] require ferromagnetic heterostructures with a high spin polarization. Promising candidates are the binary and ternary compounds of the Heusler alloys [4-5] that exhibit a high spin polarization and are lattice matched to the semiconductor substrate. Here we report on ferromagnetic resonance (FMR) results of thin layers of the Heusler alloy Fe3Si on GaAs(001) and compare them with that of pure Fe films grown under identical conditions. The films were prepared by standard molecular-beam epitaxy onto in-situ grown GaAs(001) buffer layers terminated by the c(4x4) superstructure forming the well-defined substrate surface. The growth parameters, i.e., temperature, thickness and Si content, have been varied in a wide range accompanied by detailed characterization of the structural and magnetic properties. FMR is a powerful method to investigate the magnetic anisotropy of ferromagnetic thin films, in particular to determine the magnetocrystalline anisotropy constants with high precision. The theoretical evaluation is based on the Landau-Lifshitz-Gilbert equation of motion for the dynamics of FMR. It includes the respective magnetocrystalline anisotropy energy and thus the anisotropy constants which define the orientation and hardness of the magnetic axes. They are introduced as fitting parameters for the calculation of the angular evolution of the magnetic anisotropy. In addition, the linewidth of the FMR signal provides information on the relaxation of the magnetization and its interplay with the crystal lattice.

References [1] A. Ney, C. Pampuch, R. Koch, and K. H. Ploog, Nature, 425, 485 (2003). [2] X. Jiang, R.Wang, S. van Dijken, R. Shelby, R. Macfarlane, G. S. Solomon,

J. Harris, and S. S. P. Parkin, Phys. Rev. Lett. 90, 256603 (2003). [3] Y. Ando, K. Hamaya, K. Kasahara, Y. Kishi, K. Ueda, K. Sawano, T. Sadoh,

and M. Miyao, Appl. Phys. Lett. 94, 182105 (2009). [4] M. Ramsteiner, O. Brandt, T. Flissikowski, H. T. Grahn, M. Hashimoto,

J. Herfort, and H. Kostial, Phys. Rev. B 78, 121303R (2008). [4] J. Herfort, H.-P. Schönherr, K.-J. Friedl and, and K. H. Ploog, J. Vac. Sci.

Technol. B 22, 2073 (2004).


Tailoring Carbon Nanostructures: Unravelling the Electronic Properties of Low-Dimensional Quantum Solids

T. Pichler

Faculty of Physics, University of Vienna

The presentation will give an overview on our current research focus on the electronic properties of low dimensional quantum solids. These properties are

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strongly influenced by basic correlation effects. Archetypical examples of these systems are fullerenes, graphene, graphite and single wall carbon nanotubes (SWCNT) which are determined by the local arrangement of their sp2 hybridised carbon atoms, such that their character is either semi-metallic, insulating, semiconducting or metallic. Examples of the recent work on how one can analyse these electronic properties using high energy spectroscopy (electron energy-loss, photoemission and x-ray absorption spectroscopy) as a probe will be presented. Special emphasis will be given to the influence of basic correlation effects and local field corrections on the electronic properties of graphene, graphite and SWCNT. The latter exhibit for metallic tubes a Luttinger liquid behavior. Special emphasis will be on the influence of the bundling/ debundling (van der Waals interaction) and the influence of metallicity selected, i.e. purely metallic vs. purely semiconducting, SWCNT will be given. Furthermore, an overview on how to functionalize them in order to tailor their electronic structure will be given. This includes examples for the three alternative doping routes, namely, substitution, intercalation and endohedral doping (e.g. by filling with fullerenes, metals and metallocenes) as well as examples for the growth of defined innertubes from the different precursors via a thermal nanochemical reaction. In comparison to graphite intercalation compounds, the electronic structure of doped graphene will be unravelled. For metallic functionalized nanotubes doping induced changes will be discussed in the framework of a dimensionality crossover which causes a change from a one-dimensional metal to a normal Fermi liquid. The detailed understanding of these fundamental electronic properties of functionalised fullerenes, graphite, SWCNT and graphene is key to their future success.


Nanocrystallization by Heating of Amorphous Zr3Al Made by Repeated Cold Rolling

D. Geist1*, S. II 2, K. Tsuchiya2, G. Stefanov3, H.P. Karnthaler1 and C. Rentenberger1

1Physics of Nanostuctured Materials, Faculty of Physics, Univ. of Vienna, 1090 Vienna, Austria 2Hybrid Materials Center, National Institute for Materials Science, Tsukuba 305-0047, Japan 3Inst. of Metal Science Acad. Angel Balevski, Bulgarian Acad. of Sciences, 1574 Sofia, Bulgaria *Corresponding author: [email protected]

Nanocrystalline materials (i.e. materials with a grain size < 100 nm) are of strong scientific interest because of the possible changes of the materials’ properties. Kilmametov et al. [1] showed that the ion irradiation resistance of the intermetallic compound NiTi can be enhanced by nanostructuring the material by severe plastic

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deformation (SPD). Zr3Al is an interesting intermetallic compound in this context because it was proposed as a nuclear structural material, but showed the drawback of amorphization upon ion irradiation. Nanostructuring could be a way to bypass this disadvantage. Repeated cold rolling and intermediate folding (RCR) is a promising SPD method because it was shown that the grain sizes that can be achieved are often smaller than those achieved by any other SPD method [2]. Because of its iterative character, in principal unlimited amounts of strain can be induced by this method rendering the samples nanocrystalline or amorphous. In the present work, coarse crystalline Zr3Al was deformed by RCR. Samples deformed by up to 80 folding cycles (true strain 80 = 6 600 %) were studied by X-ray diffraction (XRD) and transmission electron microscopy (TEM). After 80 foldings, a large volume fraction of the material was amorphous. The mostly amorphous samples were heated to temperatures up to 973 K in a differential scanning calorimeter. Using different heating rates, the activation enthalpy of the recrystallization process and the crystallization enthalpy were determined. TEM and XRD measurements of the heat-treated samples showed that the initial nanocrystallization does not result in the equilibrium Zr3Al structure. A metastable crystal structure forms, which slowly transforms into the equilibrium structure at higher temperatures.

References [1] A.R. Kilmametov, D.V. Gunderov. R.Z. Valiev, A.G. Balogh and H. Hahn,

“Enhanced ion irradiation resistance of bulk nanocrystalline TiNi alloy”,Scripta Materialia 59 (10), 1027-1030 (2008)

[2] G. Wilde, “Synthesis of bulk nanocrystalline materials and bulk metallic glasses by repeated cold rolling and folding (RCR)”, Materials Science Forum 579, 109-133 (2008)


AT&S Prize Lecture:

Simulation of Coherent, Large-Scale Nanostructures

F. Libisch

Institute for Theoretical Physics, Vienna University of Technology

Nanodevices have become popular systems to investigate a wide variety of physical effects. The term "nanodevice" in this context refers specifically to the size that exceeds microscopic dimensions but still lies below the inelastic mean free path. The dynamics of such devices is governed by a wave equation, the Schrödinger equation. Applications of the resulting quantum interference effects include the realization of "qubits" in solid-state devices, high-precision interference-based metrology, or tunable semiconductor lasers.

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Current materials for coherent nanodevices include carbon-based thin films, GaAs heterostructures, superconducting circuits and quantum wells. The length scales involved range from a few Ångström, the typical size of a defect or adsorption site, to the linear dimension of the device itself, up to several micrometers and more. Furthermore, microwave cavities or acoustic resonators of macroscopic dimensions have been used as experimental "quantum simulators" to measure the dynamics of wave equations on a simple table-top experiment. To treat this wide range of different materials and dimensions, we present a flexible, robust and versatile set of numerical tools to treat eigenstates, time evolution and transport. We focus in particular on graphene, the first true two-dimensional (2D) solid. Graphene is attracting considerable attention, mostly due to its unique dynamics of electrons near the Fermi energy which closely mimics that of a massless Dirac Hamiltonian. Due to its unique band-structure, quantum interference effects like the quantum-hall effect have been realized at room temperature. However, lattice defects, substrate interaction, and chemisorbates destroy the high symmetry of idealized graphene. Conversely, one could functionalize graphene structures by specific chemical doping at the edges to tailor device properties. The understanding of the effect of defects, adsorbates and impurities on device properties is thus key to the fabrication of graphene-based nanodevices that exploit its unique properties.


Organic Dielectrics Influence the Crystallographic Structure of Pentacene Thin Films

A. Moser2(a), H.-G. Flesch(a), A. Neuhold(a), M. Edler(b), T. Griesser(b), M. Marchl(a),A. Golubkov(a), G. Trimmel(c), A. Haase(d), D.-M. Smilgies (e), J. Jakabovi (f),E. Zojer(a), and R. Resel(a)

(a) Institute of Solid State Physics, Graz University of Technology, Austria (b) Institute of Chemistry of Polymeric Materials, University of Leoben, Franz-Josef Straße 18, 8700 Leoben (c)Institute of Chemistry and Technology of Organic Materials, Graz University of Technology, Stremayrgasse 16, 8010 Graz (d) JOANNEUM RESEARCH Forschungsgesellschaft mbH, Institute of Nanostructured Materials and Photonics, Franz Pichlerstrasse 30 A-8160 Weiz, Austria (e) CHESS Center, Cornell University, 14850 Ithaca, New York, USA (f) Department of Microelectronics, Slovak University of Technology, Ilkovi ova 3, 812 19 Bratislava, Slovakia

X-ray diffraction as well as atomic force microscopy experiments have been performed to investigate thin films of pentacene. The films were deposited on thermally grown SiO2 pre-covered by different organic layers. Modifying substrates

2 [email protected], www.if.tugraz.at

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in that way is a common method in organic thin-film transistor research. It is known that the substrate pre-treatments have a strong impact on the performance of the device as well as on the growth of the active layer. However, there are few reports about the influence on the crystalline properties of pentacene. In this work three different systems have been investigated. For one sample series vacuum deposited polymeric Parylene C - with varying thicknesses - was used as the dielectric layer. A second series of dielectric layers was prepared by spin coating a photoreactive polymer (PBHND [poly(bicyclo[2.2.1]hept-5-ene-2,3-(2-nitrobenzyl)dicarboxylate)]) onto the wafer. Subsequently the samples were exposed to UV-light for different time spans. For the third class of systems, a self assembled film of T-SC/SA [4-(2-(trichlorosilyl)ethyl)benzene-1-sulfonyl chloride (T-SC), 30% sulfonic acid T-SA] was used to modify the SiOx surface. From the obtained x-ray data we find that the investigated pentacene films are polymorphic and consist of the two commonly observed crystal phases, namely the thin film phase and the Campbell phase. On weakly interacting substrates, these phases are typically oriented with their (001) lattice planes parallel to the substrate surface. Yet in the present investigation it is found that for some dielectric layers the (001) planes of the thin film phase are tilted approximately 3° and of the Campbell phase about 10° with respect to the substrate surface. These small deviations in the structure have a large influence to the in-plane diffraction patterns. Therefore, the changes in the patterns can be unambiguously attributed to the change of preferred orientation.

Figure1: Scattering pattern of a pentacene thin film deposited on top of a 5 nm thick parylene film. The diffraction spots can be indexed with the known thin film (grey) and Campbell (white) phase by choosing an approximately 3° and 10° tilt of the 001 direction from the surface normal of the substrate. The radii of the rings correspond to the structure factor of the diffraction spots.

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Anton Paar Prize Lecture:

Electronic Interactions of Slow Ions

D. Primetzhofer, S.N. Markin, M. Spitz, and P. Bauer

Institut für Experimentalphysik, Johannes Kepler Universität, Linz, Austria

An investigation of the interaction of slow light ions with solids is of importance for surface science applications and fundamental understanding of electronic properties of different classes of materials. Knowledge of charge exchange processes is urgently required in quantitative surface analysis as applied in Low-energy ion scattering (LEIS) experiments. These processes are linked to the electronic structure of the sample. The band structure of solids, in turn, influences the propagation of ions in matter, i. e. the inelastic energy loss due to electron hole pair excitation.Charge exchange processes like neutralization or reionization determine not only the ion yield in a LEIS experiment and thus its sensitivity, but also the probed information depth [i]. Recent experiments have shown that the neutralization behaviour of noble gas ions scattered from single crystal surfaces is far from trivial and strong crystal effects have to be expected [ii]. Electron hole pair excitation along the trajectory gives rise to deceleration of the ion via electronic stopping power, S = -dE/dx, which – at least for a free electron gas – is assumed to be velocity proportional: S = Q·v, as long v << vF, the Fermi velocity of the sample [iii]. For Cu and Au, a velocity threshold vth is observed for H+ and He+, at vth 0.18 a.u., i.e. 4·105 m/s. Below vth only sp-electrons can be excited, while the d-electrons cannot, since the DOS of the d-electrons does not extend up to the Fermi level [iv]. For LiF with a band gap of 14 eV, electron-hole pairs can be excited by ions only if the velocity is larger than 0.09 a.u [v]. Below, ions are slowed down only by atomic collisions. This threshold is lower than predicted [vi]. A similar behaviour was found for other ionic insulators with large band gaps, e.g. KCl. Comparison of the results for LiF and Cu or Au leads to the question why vth for insulators is so low. It might be concluded that the effective gap in LiF is 1 eV, in contrast to theoretical prediction [vii].

References [i ] D. Primetzhofer, M. Spitz, S.N. Markin, and P. Bauer, Phys. Rev B (2009) [ii] D. Primetzhofer, S.N. Markin, J.I. Juaristi, E. Taglauer, and P. Bauer, PRL

(2008) [iii] P.M. Echenique, F. Flores, and R. H. Ritchie, Solid State Physics (1990) [iv] S.N. Markin, D. Primetzhofer, M. Spitz, and P. Bauer, Phys. Rev. B (2009) [v] S.N. Markin, D. Primetzhofer, P. Bauer, PRL (2009) [ vi] J.M. Pruneda, D. Sánchez-Portal, A. Arnau, J.I. Juaristi, and E. Artacho,

PRL (2007) [vii] B. Solleder, L. Wirtz and J. Burgdorfer, Phys. Rev. B (2009)

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Current Conservation in Nonequilibrium Networks

C. Uiberacker and J. Oswald1

1Montanuniversität Leoben, Inst. f. Physik; [email protected]

In contrast to the well-known Chalker-Coddington network model [1], which uses elastic single particle quantum tunneling at saddle points to obtain critical exponents, the nonequilibrium network model [2-4] describes quantities of nonquilibrium thermodynamics by using the Landauer-Büttiker approach. In case of local linear transport at saddles we show that the chemical potential distribution can be obtained, respecting the boundary condition of injected currents, from an inhomogeneous system of linear equations. It turns out that the solution is uniquely determined by the boundary condition, no matter how many current contacts we have. The seeming contradiction can be resolved by the fact that current is automatically conserved in the network.

References [1] J. T. Chalker and P. D. Coddington, “Percolation, quantum tunnelling and

the integer Hall effect“, J. Phys. C: Solid State Phys. 21, 2665 (1988). [2] J. Oswald, “A new model for the transport regime of the integer quantum Hall

effect: The role of bulk transport in the edge channel picture”, Physica E 3,30 (1998).

[3] J. Oswald and M. Oswald, “Circuit type simulations of magneto-transport in the quantum Hall effect regime“, J. Phys.: Condens. Matter 18, R101 (2006).

[4] C. Uiberacker, C. Stecher, and J. Oswald, “Systematic study of nonideal contacts in integer quantum Hall systems”, Phys. Rev. B 80, 235331 (2009).

FKP-NESY-19: Grüner Hörsaal, Fr, 10 Sept, 09:15 Uhr

InGaAs/GaAsSb/InP Material System for MIR and THz Quantum Cascade Lasers

A. M. Andrews1,2, M. Nobile1, C. Deutsch2, P. Klang1, H. Detz1, A. Benz2,W. Schrenk1, K. Unterrainer2, and G. Strasser1,3

1Center for Micro- and Nanostructures, 2Photonics Institute, Vienna University of Technology, Austria, Contact: [email protected] at Buffalo, State University of New York, Buffalo, USA

State-of-the-art mid-infrared (MIR) quantum cascade lasers (QCLs) use the InGaAs/InAlAs/InP material system due to its low effective mass and high conduction band offset, while the terahertz (THz) and MIR QCLs use the

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GaAs/AlGaAs material systems due to its tailorable band offset while remaining lattice matched. Intersubband (ISB) unipolar devices, like QCLs, use bandgap engineering to control electron energy levels and thus photon wavelengths. In these material systems the barriers contain aluminum, which provides a high conduction band offset (CBO) of 0.52 eV for InGaAs/InAlAs and variable CBOs up to 0.39 eV for GaAs/AlGaAs, but at the cost of a high effective mass in the barrier layers. The InGaAs/GaAsSb/InP material system [3,4], CBO of 0.36 eV, has the potential to improve ISB devices by the elimination of aluminum from the barriers, reducing the effective mass, and Al-oxide from the exposed surfaces, therefore simplifying subsequent post processing and/or regrowth. The low effective mass for electrons leads to a spreading of the electron wave function and a higher optical matrix element and thus improved laser gain. As a consequence of the low effective mass, the barriers must be thicker, which makes them less sensitive to deviations in the growth rate caused by cell shutter transients or interface roughness. We present high power MIR and the first THz QCLs based on In0.53Ga0.47As/GaAs0.51Sb0.49, Figure 1. The samples discussed here were grown in a solid-source Riber Compact 32 system with valved crackers for both group V elements [5]. The valved crackers allow a stable As4 and Sb2 flux, which is required for reliable lattice-matching. Switching between the materials therefore can be done by shutter operations. A substrate temperature of 480 °C was used to minimize the dependence of the GaAsSb composition on substrate temperature. Growth rates of 1.07 μm/h for InGaAs and 0.52 μm/h for GaAsSb are ensured by X-ray diffraction analysis of calibration superlattices. MIR QCLs emitting at 10.7 μm with 1.2 W optical output powers and a threshold as low as 0.6 kA/cm² were realized [Nobile et al. submitted APL]. In addition, a 10 μm thick THz QCL consisting solely of 170 active region periods showed emission around 75 μm with a threshold current density of 1.7 kA/cm² and operation up to 105K [Deutsch et al. submitted APL], comparable to published InGaAs/InAlAs THz QCLs.

References M. Nobile, H. Detz, E. Mujagi , A.M. Andrews, P. Klang, W. Schrenk and G. Strasser, Appl. Phys. Lett. 95, 041102 (2009) M. Nobile, P. Klang, E. Mujagi , H. Detz, A.M. Andrews, W. Schrenk and G. Strasser, Electron. Lett. 45, 1031 (2009) H. Detz, A.M. Andrews, M. Nobile, P. Klang, E. Mujagi , G. Hesser, W. Schrenk, F. Schäffler, G. Strasser, J. Vac. Sci. Technol. B 28, C3G19 (2010)


Ring Cavity Induced Performance Enhancement in Mid-Infrared and Terahertz Quantum Cascade Lasers

H. Detz1, E. Mujagi 1, Cl. Schwarzer1, P. Klang1, A. M. Andrews1, 2, W. Schrenk1,C. Deutsch2, K. Unterrainer2, and G. Strasser1

1Institute for Solid State Electronics and Center for Micro- and Nanostructures,

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TU Vienna, 1040 Vienna, Austria, 2Photonics Institute, TU Vienna, 1040 Vienna, Austria

Quantum cascade lasers (QCLs) are well established as reliable laser sources from the midinfrared (MIR) to the terahertz (THz) spectral region. These coherent sources of light are attractive compact emitters for a broad range of applications, such as free space communications, spectroscopy, imaging and heterodyne detection. For most of these applications, symmetric far fields and low beam divergence are of special interest. However, due to small dimensions and elongated shape of the resonator, the emitted light of standard Fabry-Pérot and surface emitting QCLs is typically broad and asymmetric. Especially for THz QCLs, the sub-wavelength dimensions of laser ridge facet lead to inhomogeneous diffractive-like patterns and limited output intensities. We describe ring cavity surface emitting lasers (RCSELs) and demonstrate how MIR and THz emission can effectively be emitted using an advanced ring geometry [1,2]. Beam narrowing is given by constructive interference of light waves passing through the slits of a radial, light out-coupling grating on top of the laser. This results in the realization of single-mode operating ring-cavity QCLs with strongly collimated symmetric surface emission, with a full width at half maximum of 3° and 15° for MIR and THz emitters, respectively. For the latter the reduced divergence gives a two-fold power enhancement compared to standard edge-emitters. We will present an extensive study in terms of output power, threshold behavior, beam shaping, dynamic beam steering and polarization characteristics. Furthermore we will talk about coherent coupling, two-dimensional integration of ring QCLs and their applicability in spectroscopy.

References [1] E. Mujagi , C. Deutsch, H. Detz, P. Klang, M. Nobile, A. M. Andrews, W.

Schrenk, K. Unterrainer, and G. Strasser, „Vertically emitting terahertz quantum cascade ring lasers“, Appl. Phys. Lett. 95, 011120 (2009).

[2] E. Mujagi , M. Nobile, H. Detz, W. Schrenk, J. Chen, C. Gmachl, and G. Strasser, “Ring cavity induced threshold reduction in single-mode surface emitting quantum cascade lasers”, Appl. Phys. Lett. 96, 031111 (2010).


Au – Free Growth of InAs Nanowires

B. Mandl

Institute for Semiconductor- and Solid State Physics, University of Linz, Austria

Lattice mismatch and defects at boundaries between different semiconductors are limiting factors hindering the fabrication of otherwise extremely appealing heterostructures. It seems that nanowires provide a way to circumvent many of such problems due to the small contact area between substrate and wire, which

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apparently can lead to almost defect-free structures even if the interface region itself may contain some defects. Nanowire growth makes material combinations possible, which have long been envisioned but are very difficult to realize with conventional heterostructure growth, like III-V compounds on top of silicon substrates. One such example is the growth of InAs nanowires, which - like many other nanowire materials – are usually grown in a vapor-liquid-solid like growth mode with Au seed particles. InAs is of considerable interest for the electronicdevices due to its low effective electron mass. However, for the growth on Si, gold is rather unwanted since it acts as a deep trap in Si, and thus it is crucial to develop other growth schemes without the need for Au seed particles. We have achieved the controlled Au-free growth of InAs nanowires on Si, as well as on III-V substrates, using SiOxor organic layers to "nucleate" wire growth. [1,2] Furthermore position controlled growth of InAs on Si has also been demonstrated in the literature. [3] However, in contrast to Au-nucleated nanowire growth, so far only little is known about the details of this Au-free growth mechanism.

In our work we studied the nucleation and growth mechanism of Au – free grown InAs nanowires. For the growth of these wires InAs and InP substrates are covered with a thin layer of SiOx and wires are grown using metal-organic vapor phase epitaxy (MOCVD). As the possibilities for in-situ observation of growth in MOCVD are very limited, a series growth studies were carried out. In particular, to clarify the origin of the Au-free InAs growth on SiOx covered InAs in-situ LowEnergy Electron Microscopy (LEEM) and x-ray photo electron emission microscopy experiments were carried out. With these in-situ heating experiments it was determined that In droplets play a crucial role for the wire growth. By comparing the obtained results with such from commonly used growth mechanisms we determine the mechanism responsible for our wire growth and develope a corresponding model.

Finally a comparison of our results to reports of Au free growth in the literature is made to evaluate how general the derived growth model is.

[1] B. Mandl et al., Nano Lett., 2006, 6 (8), 1817 - 1821 [2] T. Martensson et al., Advanced Materials, 2007, 19 (14), 1801 - 1806 [3] K. Tomioka et al., Nano Lett., 2008, 8 (10), 3475 – 3480


Two - Photon Excitation oF InAs / GaAs Quantum Dots

T. Moldaschl1, W. Parz1, T. Müller1, S. Golka1, G. Strasser2,3 and K. Unterrainer1,3

1Institut für Photonik, TU Wien, Gußhausstrasse 27-29 / 387, 1040 Wien [email protected] für Festkörperelektronik, TU Wien, Floragasse 7, 1040 Wien 3Zentrum für Mikro- und Nanostrukturen, TU Wien, Floragasse 7, 1040 Wien

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Semiconductor quantum dots (QDs) gained significant impact because of their atom - like properties. Long coherence times of the excitonic states permit the realization of quantum optics experiments, so far only possible with single trapped atoms. Among these realizations are the implementation of quantum logic gates [1] using single QDs. A key effect for the coherent control, necessary for this implementation, is the Rabi Oscillation, which has been demonstrated in single- and ensemble QDs [1-3]. The drawback of this mechanism however, is the need for high excitation intensities, considering the semiconductor nature of the QDs and their host material. In this work we show the consequences that arise from using high power resonant QD excitation. As a spectroscopic technique we use time resolved spectral hole burning (SHB) spectroscopy. This differential transmission scheme consists of narrow band ps pump pulses, generated through spectral shaping of the 80 fs pulses provided by the Ti:Sapphire Laser system, which are directly used for probing. The sample is a 30 layer InAs QD stack grown on GaAs. In order to be optically accessible by the laser system, the sample underwent a rapid thermal annealing treatment resulting in a blue shifted ground state transtion energy of around 1280 meV. Under low excitation intensities, the excitonic spectral hole |X> as well as the biexcitonic spectral antihole |XX> is visible if both pump and probe pulses share the same linear polarization. Once the excitation intensity is increased, there appear additional spectral holes (|X'> and |XX'>) symmetrically around the resonant |X> spectral hole. These spectral holes are unambiguously assigned to resonant two - photon excitation of the biexciton, proven by polarization and intensity dependent measurements. The higher energy spectral hole |X'>corresponds to the exciton state, whereas the lower energy |XX'> is created through stimulated emission from the biexcitonic cascade |XX'> to |X'>, initiated by probe photons at this respective energy [4]. The second feature of the SHB spectra is an overall broadening of the absorption line, which is caused by Coulomb interactions between the resonantly created excitons in the QDs and carriers that are generated by two - photon absorption in the surrounding GaAs matrix, which are prone to capture and relaxation processes. To prove this interpretation the photoluminescence of the sample was recorded only using pulsed two - photon excitation providing a significant amount of carriers. This eventually gives rise to an additional source of decoherence for QDs under resonant excitation [4].

References [1] Li, X. et al., “An all optical quantum gate in a semiconductor quantum dot”,

Science 301, 809 (2003)

[2] Zrenner, A. et al., “Coherent properties of a two – level system based on a quantum dot photodiode“,Nature 418, 612 (2003)

[3] Borri, P. et al., “Rabi oscillations in the excitonic ground state transition of InGaAs quantum dots“, Phys. Rev. B 66, 081306 (2002)

[4] Moldaschl, T. et al. “Two – photon spectral hole burning spectroscopy of InAs / GaAs quantum dots“, Appl. Phys. Lett. 97, 1 (2010) (page not assigned yet)

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Giant Ge Surface Diffusion Length And Stable Island Sizes During Stranski-Krastanow Nucleation of SiGe/Si(001) Islands

M. Brehm*, M. Grydlik, F. Hackl, T. Fromherz, F. Schäffler and G. Bauer

Institute of Semiconductor and Solid State Physics, Johannes Kepler University A-4040 Linz, Austria

During SiGe island nucleation in the Stranski-Krastanow growth mode, a giant Ge surface diffusion length is observed across boundaries between substrate areas with different nucleation states of MBE grown SiGe islands. The different nucleation states of islands can either be due to a pit-patterned substrate adjacent to a plane substrate or by covering a part of the substrate with a shutter. In the case of a pit-patterned substrate, the impinging Ge flux is first consumed for the formation of {105} SiGe facets that decorate the side walls of the pits, while on the planar substrate regions the Ge coverage is already sufficient for the formation of a wetting layer (WL) with overcritical thickness on that random island nucleation takes place along the routes discussed recently [1]. On the pit-patterned field we observe an exponential decay of the island volumes in the pits with increasing distance from the border between the patterned and un-patterned regions as well as a zone denuded from islands on the planar part of the substrate similar to what was reported for line-patterned substrates [2]. We observe distinctly different volume decay constants for the different morphological evolution stages of the islands that allows us to extract the Ge capture cross-section of the respective SiGe island shapes (transition pyramids, pyramids, transition domes, domes, super-domes, as commonly defined [1]). As far as 50 m from the border of the patterned field islands with a larger volume as compared to that observed in the center of the patterned area are observed, indicating that Ge diffuses from the border at least this distance into the patterned area. This giant diffusion length is also observed in a control experiment, in that a part of the substrate is shaded off the Ge flux by a shutter. Still, clear evidence of islands and a Ge wetting layer is observed below the covered area by atomic force microscopy and spatially resolved photoluminescence (micro-PL) spectroscopy more than 175 m away from the shutter edge. Surprisingly, for domes of a critical size a vanishingly small Ge capture cross-section is observed, where this size depends on the growth temperature. Thus, in our experiments the domes appear as stable islands with equal volumes on the planar and patterned part of the substrate within the experimental error. We show that dislocated superdomes form only after each pit on the 200 × 200 m2 patterned substrate area is occupied by a fully developed dome. Concomitant with the appearance of superdomes, the PL of the ordered islands is quenched, indicting that this transition is triggered by dislocation formation. We demonstrate that, as a consequence of the large Ge surface diffusivity, the critical coverage, at that the transition between domes and superdomes occurs, inversely depends on the area of the substrate pattern unit cell as all Ge deposited within this area diffuses into the pits once a homogenous dome array is formed over the complete patterned area. Thus, the combination of spatially resolved growth experiments in combination with micro-PL

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experiments provides novel insight into the role of surface kinetics during Stranski- Krastanow growth on planar and patterned substrates.

[1] M. Brehm et al., Phys. Rev. B 80, 205321 (2009). [2] G. S. Kar et al., Phys. Rev. Lett. 93, 246103 (2004).


X-Ray Scattering Studies of Magnetic CoFeO Nano-Cubes

R.T. Lechner1, G. Popovski1, W. Heiss2, B. Aichmayer3 and O. Paris1

1Institut für Physik, Montanuniv. Leoben, 8700 Leoben, Austria; [email protected] Institut für Halbleiter- und Festkörperphysik, Johannes Kepler Univ. Linz, 8010 Linz, Austria 3 Max-Planck-Institut für Kolloid- und Grenzflächenforschung, 14476 Potsdam, Germany

We have studied with small and wide angle x-ray scattering (SAXS-WAXS) techniques magnetic CoFe2O4 core-shell nanocrystals (NC) in solution. The new type of strongly exchange-coupled iron oxide-based core/shell NC with a cubic shape (see Fig. 1a) are chemically synthesized and consist according to transmission electron diffraction (TEM) studies of an antiferromagnetic (AFM) core of ferrous oxide (wüstite, FexO), which is surrounded by a ferrimagnetic (FiM) shell of a metal ferrite (CoFe2O4) [1]. These magnetic nanoparticles show not only a great potential for novel magneto-electronic devices, but also for bio-medicalapplications. In this work, we have tried to gain structural information of the core and shell structure independently. The SAXS-WAXS experiments have been carried out at the beamline �-spot at the synchrotron HZB-BESSYII (Berlin). The scattering spectra were recorded with a 2D CCD-detector in a setup, which enables

(c)

(a) (b) Fig.1: (a) TEM image of a thin film formed by 11-nm cubic FexO/CoFe2O4NCs. (b) 2D WAXS spectrum ofFexO/CoFe2O4 cubes with nominal 14 nm size measured in a 1wt% solution sealed in quartz-glass-capillaries with 1.5 mm diameter. (c) SAXS intensity vs. scattering vector q. From the comparison to the theoretical scattering model we derive a size of~12 nm for the magnetic nano-cubes. The scattering spectra were recorded using a x-ray energy of 15 keV at the beamline -spot at HZB-BessyII, Berlin.

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the detection of the low (SAXS) and the large q-range (WAXS) from 0.5 nm-1 to 50 nm-1, within one single measurement (see Fig. 1(b)). From the SAXS modulated intensity distribution over q and the fit with the theoretical scattering curve we can deduce a cube size of ~11.8 ± 1.4 nm (see Fig. 1(c)). From the position and the width FWHM of the structural Bragg peaks at large q-values (WAXS) we derive the size of the wüstite FexO-core of ~9 nm and hence a thickness of the surrounding CoFe2O3 shell to ~1.5 nm. Supported by the Austrian Science Fund FWF (P18942) and the European Community's Seventh Framework Programme (FP7/2007-2013 under n.°226716).

References [1] M.I. Bodnarchuk, M.V. Kovalenko, H.Groiss, R.Resel , M. Reissner,

G. Hesser, R.T. Lechner,W.Steiner, F.Schäffler, and W. Heiss, Small 5 (20), 2247-2252 (2009)

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8.6 GEP – Geschichte der Physik

Montag - Monday 6 September 2010 / Haus der NaturFachausschuss Geschichte der Physik –

Scientific Committee History of Physics (GEP) Parallel Session GEP

Zeit Time



15:30 - 15:50 Bruno P. Besser (ÖAW),

Walter M. Iber Willi Nordberg – ein Physiker in der Fernerkundung

15:50 - 16:10 Harald Markum (TU Wien)

Der Begriff der Zeit von Aristoteles bis zur nichtkommutativen Geometrie

16:10 - 16:30 Sonja M. Schreiner (Univ. Wien)

Die Jesuiten und / oder wissenschaftlicher Fortschritt: Joseph

du Baudory‘s De novorum systematum inventoribus quid sentiendum oratio als

(typisches?) Beispiel

16:30 - 16:50 Stanislav Južni(Univ. of Oklahoma)

Habsburg Enlightenment electricity and vacuum for far east

16:50 – 17:10 Franz Pichler (Univ. Linz)

Robert Adler: Angewandte Physik im Bereich

der Elektronenröhren und des Ultraschalls

17:10 - 17:30 Peter Maria Schuster (EchoPhysics)

„Erinnerungen an ProfessorDr. Fritz Kohlrausch“: –

In Memoriam Hofrat DI Franz Allmer

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GEP-1: Haus der Natur, Mo, 6 Sept, 15:30 Uhr

Willi Nordberg – Ein Physiker in der Fernerkundung

B. P. Besser1 und W. M. Iber2

1 Institut für Weltraumforschung, Österreichische Akademie der Wissenschaften, Schmiedlstraße 6, 8042 Graz Email: [email protected] Ludwig Boltzmann Institut für Kriegsfolgen-Forschung, Ludwig Boltzmann Gesellschaft, Schörgelgasse 43, 8010 Graz

Dem (Geo-)physiker Willi Nordberg (1930-1976) und der historischen Entwicklung der Weltraumforschung und Fernerkundung ist heuer (bis 31. Oktober 2010) eine Ausstellung im Gerberhaus der südsteirischen Stadtgemeinde Fehring gewidmet [1]. Willi Nordberg, geboren in Fehring, studierte in den beginnenden Fünfzigerjahren an der Universität Graz und emigrierte kurz nach seiner Promotion in die Vereinigten Staaten von Amerika. Dort begann er seine physikalischen Arbeiten an meteorologischen Problemen im Rahmen des Army Signal Corps. Mit der Gründung der NASA und des Goddard Space Flight Centers wechselte er dorthin und war beschäftigte sich mit Fragen der Satellitenmeteorologie, die in der Projektleitung bei der TIROS-Wettersatelliten-Serie gipfelte. Mit Ende der sechziger Jahre übernahm er die Leitung des weltweit ersten nichtmilitärischen Fernerkundungsprogrammes dem später der Name LANDSAT gegeben wurde. Dabei wurde sowohl das weltraum- als auch das erdgebundene Forschungssegment erfolgreich aufgebaut. Nordberg waren nach der erfolgreichen Installation des Satellitensystems nur mehr wenige Forschungsjahre gegönnt, und so konnte er die vielfältigen Früchte „seiner Saat“ nicht mehr ernten.

References [1] Besser, B.P, W.M. Iber, St. Karner (Hrsg.), “Nordberg – Der Weg in den

Weltraum”, Stadtgemeinde Fehring, Fehring und Graz, 224 S., 2010.


Der Begriff der Zeit von Aristoteles bis zur nichtkommutativen Geometrie

H. Markum1

Atominstitut, TU Wien E-Mail: [email protected]

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Aristoteles definiert die Zeit als abgeleitete Größe aus der Bewegung. In der klassischen Mechanik geht die Zeit als Parameter in die Newtonschen Bewegungsgleichungen ein. In der Quantenmechanik sowie in der Quantenfeldtheorie ist die Zeit ebenfalls ein Parameter in der Schrödinger- oder Dirac-Gleichung. In der speziellen Relativitätstheorie ergibt sich eine Zeitdilatation im bewegten Bezugsystem, die Zeit bleibt jedoch ein (relativer) Parameter. Ebenso in der allgemeinen Relativitätstheorie, wo etwa bei gewissen Metriken Phänomene auftreten können wie Lösungen in die Vergangenheit. Die fundamentalen Gleichungen der Physik sind invariant bei Zeitumkehr. Der zweite Hauptsatz der Thermodynamik verletzt diese Symmetrie und führt zum Auftreten eines Zeitpfeils. In nichtkommutativen Geometrien wird die Zeit zu einem Operator. Atomuhren machen die Zeit und die Frequenz zu den mit höchster Präzision messbaren physikalischen Größen. Ein Überblick über den Begriff Zeit in den verschiedenen Gebieten der Physik soll gegeben werden.


Die Jesuiten und / oder wissenschaftlicher Fortschritt: Joseph du Baudory‘s De novorum systematum inventoribus quid sentiendumoratio als (typisches?) Beispiel

S. M. Schreiner1, F. Römer2 und M. E. Lippitsch3

1Institut für Klassische Philologie, Mittel- und Neulatein, Philologisch-Kulturwissenschaftliche Fakultät, Universität Wien, Dr. Karl Lueger Ring 1, A-1010 Wien, [email protected] für Klassische Philologie, Mittel- und Neulatein, Philologisch-Kulturwissenschaftliche Fakultät, Universität Wien, Dr. Karl Lueger Ring 1, A-1010 Wien 3Institut für Physik, Naturwissenschaftliche Fakultät, Karl-Franzens-Universität Graz, Universitätsplatz 5, A-8010 Graz

Für den Schul- und Universitätsbetrieb des 18. Jahrhunderts war der Jesuitenorden von unschätzbarer Bedeutung. Die Societas Jesu spannte ihr wissenschaftliches Netzwerk über ganz Europa. Geistes- und Naturwissenschaften sind im Barock, in der Aufklärung und im Rokoko ohne die Jesuiten nicht denkbar. Einer der Gelehrten, die Theologie und Wissenschaft erfolgreich zu kombinieren verstanden, war der Franzose Joseph du Baudory (1710-1749), der nicht zuletzt durch sein entwickeltes rhetorisches Talent große Berühmtheit erlangte. 1762 kam in Paris eine neue und erweiterte Edition der Oeuvres diverses du Père du Baudory auf den Buchmarkt. Baudorys Rede „Was man von den Erfindern neuer Systeme zu halten hat” ist Teil dieser Sammelausgabe. In einer tour d’hôrizon eröffnet Baudory Einblicke in seine Gedankenwelt und entwickelt seinen ganz persönlichen Zugang zum wissenschaftlichen Fortschritt, indem er dessen Vor- und Nachteile unter permanenter Bezugnahme auf zahlreiche prominente Philosophen und Wissenschaftler erläutert.

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Habsburg Enlightenment Electricity and Vacuum for Far East

S. Južni 1

1 University of Oklahoma, 401 West Brooks, Room 512, Norman, Oklahoma 73019-0528, USA 2 Mayordoom of Kostel, Slovenia Email: [email protected]; [email protected]

The astronomical excellence of the first rate Habsburg literati Augustin Hallerstein was widely recognized recently. As the prominent first rate scientist attached to the Chinese Imperial Court he was involved in other types of research besides astronomy, but his authorship was not always clear inside the Jesuits’ collective work. Besides astronomical observations the Beijing Jesuits also provided early electricity experiment, which enabled Volta’s invention of the electrophorus and battery. The development of such devices paved the way for the longer-duration electrical observations instead of the instant ones Leyden jar experiments. The scientists urgently needed that novelty because they wanted to know a process hidden behind an interesting electrical sparking. The electrics experiments became the European fashion, as the vacuum pumps were somewhat earlier. Both entered Chinese court in Hallerstein’s time, but eventually never received the same amount of interest as Western astronomy did. One of the reasons for the Chinese doubts was the nonexistence of the broader scale technical use of vacuum or electricity during Hallerstein’s lifespan. The Empress Maria Therese’s physician Ingenhousz and other physicians educated in Leyden eventually developed broader use of electricity in scientifically somewhat backwards countries, as were Hallerstein’s native Habsburg monarchy or Japan.


Robert Adler: Angewandte Physik im Bereich der Elektronenröhren und des Ultraschalls

F. Pichler1 und H. Thim2

1Institut für formale Modelle und Verifikation, Johannes Kepler Universität Linz, [email protected] für Mikroelektronik, Johannes Kepler Universität Linz, E-Mail: [email protected]

Der Vortrag beleuchtet die Arbeiten des aus Wien stammenden im Jahre 1939 aber in die USA emigrierten österreichischen Physikers Robert Adler (1913-2007), die er in seiner langjährigen Tätigkeit bei der Zenith Radio Corp. in Chicago in der Zeit

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von 1940 bis 1987 verfasst hat. Diese betreffen die Entwicklung spezieller Elektronenröhren, wie das von ihm erfundene Phasitron (1947), eine Kathodenstrahlröhre für die Frequenzmodulation sowie Wanderfeldröhren. Im Bereich des Ultraschalls hat er elektromechanische Filter entwickelt und er gilt auch als Erfinder der Fernsteuerung zur Bedienung von Fernseh-Apparaten (1957). Weitere Beiträge von Robert Adler behandeln das Gebiet der akustischen Oberflächenwellen-Filter (SAW-Filter) und deren Anwendung in der Fernsehtechnik. Robert Adler hat mehr als 50 wissenschaftliche Arbeiten verfasst und erhielt mehr als 180 US-Patente zugesprochen. Für seine Leistungen wurde er mehrfach geehrt. Hier ist besonders die an ihn im Jahre 1980 von IEEE verliehene Edison- Medaille zu erwähnen. Robert Adler kann zu den bedeutendsten aus Österreich stammenden Physikern im Bereich der Angewandten Physik und der Nachrichtentechnik gezählt werden


„Erinnerungen an Professor Dr. Fritz Kohlrausch:“ In Memoriam Hofrat DI Franz Allmer

P.M. Schuster

Victor-Franz-Hess-Gsellschaft, Schloss 1, 8225 Pöllau, [email protected]

Einen Tag vor der Eröffnung der ÖPG Tagung 2008 am 22. September in Leoben erhielt der Verfasser von Hofrat DI Allmer einen Anruf und via E-Mail zwei kurze Notizen von ihm über Prof. Dr. Fritz Kohlrausch. Er habe geplant, diese Notizen bei derselben Tagung in Leoben vorzutragen, teilte Allmer mit, sei wegen einer Erkrankung aber leider verhindert. Er wolle diese aber gerne dem Verfasser übergeben um auf einen bedeutenden Physiker aufmerksam zu machen, der noch zu wenig gewürdigt worden sei. Er arbeite intensiv über Kohlrausch und wolle im nachfolgenden Monat mit Hilfe von Prof. Dr. Jäger, der Kohlrausch noch persönlich gekannt hatte, seine Arbeit fertig bringen. Wenige Tage später verunglückte Hofrat DI Franz Allmer tödlich.

Der vorliegende Beitrag widmet sich dem Werk und Leben von Franz Allmer, der an der Sektion GEP der ÖPG seit 2006 regen Anteil genommen hatte, und den der Verfasser bei vielen Gelegenheiten als außerordentlich kompetenten, bis ins hohe Alter rührigen, physikhistorisch interessierten Kollegen geschätzt hatte. Die persönlichen Erinnerungen von Hofrat DI Franz Allmer an Prof. Dr. Fritz Kohlrausch, die bis dato unveröffentlicht sind, werden vorgetragen.

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8.7 LHS – Lehrkräfte an Höheren Schulen

Mittwoch – Wednesday, 8 September 2010 Fachausschuss Lehrer an Höheren Schulen - Scientific Committee Physics Teachers (LHS)

Parallel Session LHS

Zeit-Time Vortragender Lecturer


Audi Max (HS 401) Abstracts und Details siehe pp. 29-31

13:15 - 13:30 Gerhard Haas (Neues Gymnasium Leoben)

Roman Ulrich Sexl - Prize: Austrian Young Physicist Tournament

13:30 - 13:45 Brigitte Pagana-Hammer (GRg3 Wien, Fak. Physik,

Univ. Wien)

Roman Ulrich Sexl - Prize: IYPT-Aufgaben: Eine didaktische

Herausforderung für den Physikunterricht

13:45 - 14:15 AYPT- IYPT Fight Demonstration,

Physics Olympiad, Physik-Fachbereichsarbeiten

Blauer Hörsaal (HS 402)


Fachausschusses LHS LHS Annual General Assembly

14:30 - 15:00 Peter Schmid (Univ. Innsbruck)

CERN Neuigkeiten vom LHC und das CERN

Outreach Programm

15:00 - 15:30 Laurenz Widhalm (ÖAW)

teilchen.at – Die Outreach- Initiative des FAKT

16:00 - 18:00

Exkursion zum Museum Haus der Natur und Science Center

Excursion to Museum Haus der Naturand Science Center

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LHS-1: Blauer Hörsaal, Mi, 8 Sept, 14:30 Uhr

CERN - Neuigkeiten vom LHC und das CERN Outreach Programm

P. Schmid

Institut für Astro- und Teilchenphysik, Universität Innsbruck, Technikerstr. 25, A 6020 Innsbruck

Der Large Hadron Collider (LHC) wurde im März 2010 im CERN in Betrieb genommen und hat seither Daten von Protonenkollisionen bei 900 GeV und 7 TeV Schwerpunktenergie geliefert. Alle Experimente funktionieren hervorragend und konnten bei den Sommerkonferenzen über eine große Zahl von Ergebnissen berichten. CERN bietet seit vielen Jahren eine breite Palette von Informationen und Besuchsmöglichkeiten für die Öffentlichkeit [1]. Die Programme mit besonderer Relevanz für Mittelschullehrer und –schüler [2] werden vorgestellt.

Literatur [1] http://public.web.cern.ch/public/en/About/About-en.html[2] http://education.web.cern.ch/education/

LHS-2: Blauer Hörsaal, Mi, 8 Sept, 15:00 Uhr

teilchen.at – Die Outreach-Initiative des FAKT

L. Widhalm

Institut für Hochenergiephysik der ÖAW, Nikolsdorfergasse 18, 1050 Wien [email protected]

Im Dezember 2009 hat das FAKT Koordinationsteam beschlossen, die Öffentlichkeitsarbeit der FAKT-Institute österreichweit zu koordinieren und zu forcieren. Der Vortragende wurde dabei gebeten die Rolle des Koordinators zu übernehmen, und hat in dieser Funktion alle Mitgliedsinstitute des FAKT besucht, die bereits existierenden Outreach-Tätigkeiten erhoben und die Vernetzung der Aktivitäten initiiert. Dieser Vortrag stellt die bereits realisierten und für die Zukunft geplanten Projekte in Hinblick auf die Relevanz für PhysiklehrerInnen und SchülerInnen vor, dazu zählen neben der Webpräsenz [1] auch die Wanderausstellung „teilchen.at“ [2], die derzeit im Rahmen der ÖPG Tagung in Salzburg zu sehen ist, und für Schulen gebucht werden kann. Weitere Programme sind „Physik zum Anfassen“ sowie spezielle Angebote zur Begabtenförderung.

Literatur [1] www.teilchen.at[2] events.teilchen.at

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8.8 MBU – Medizinische Physik, Biophysik und Umweltphysik

Donnerstag - Thursday 9 September 2010 / HS 415Fachausschuss Medizinische Physik, Biophysik, Umweltphysik -

Scientific Committee Medical Physics, Biophysics, and Environmetal Physics (MBU)

Parallel Session MBU

Zeit Time

Vortragender - Lecturer


14:25 - 14:30 Günther Schauberger (VetMed. Univ. Wien)

Eröffnung der Fachtagung MBU - Opening of the Topical Session MBU

14:30 - 15:00 Werner Schmidt (Donauspital Wien)

Medizinische Physik 2010 in Österreich: Was trägt die Öster. Ges. für Medizinische

Physik (OGMP) dazu bei?

15:00 - 15:15 Herbert Lettner (Univ. Salzburg)

Dynamik und Dosimetrie der Radonfolgeproduktablagerung

auf der Haut

15:15 15:30 Rozhin Penjweini (Univ. Wien)

Characterizing the effects of combinations of visible-infrared laser beam and blue/red-

LED-arrays on Albican candida and Pityriasis versicolor distruction


15:50 - 16:05 Khan Alam (Univ. Salzburg)

Variability of aerosol optical depth over mega city Karachi

using MODIS and AERONET data

16:05 - 16:20 M. Hussain (Univ. Salzburg)

Lung dosimetry for inhaled long-lived radionuclides

and radon progeny

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16:20 - 16:35 Günther Schauberger (VetMed. Univ. Wien)

Reconstruction of the airborne emissions by inverse dispersion modelling

and generation of synthetic emission data by a Monte Carlo approach

16:35 16:50 Thomas Wilflinger (Univ. Salzburg)

Altersabschätzung alpiner Kryokonite mit Hilfe natürlicher und künstlicher

Radionuklide

16:50 17:05 Pierre Madl (Univ. Salzburg) Waterfall-related aerosol inventory

MBU-1: HS 415, Do, 9 Sept, 14:30 Uhr

Medizinische Physik 2010 in Österreich: Was trägt die Österreichische Gesellschaft für Medizinische Physik (OGMP) dazu bei?

W.F.O. Schmidt

Institut für Radioonkologie, Donauspital Wien A 1220 Wien, Langobardenstrasse 122 [email protected]

In einem Übersichtsvortrag sollen aktuelle Aktivitäten der Österreichischen Gesellschaft für Medizinische Physik vorgestellt werden. Dazu zählen insbesondere:

Die Vorbereitung einer Dreiländertagung (Deutschland, Schweiz, Österreich) in Wien im September 2011.

Fortbildungsveranstaltungen im Herbst 2010 (u. a. zu Röntgendiagnostik und bildgebenden Verfahren).

Einbindung der österreichischen Medizinphysiker in gesamteuropäischeAktivitäten wie Fort- und Weiterbildung sowie Kriterien zur wechselseitigen Anerkennung von Medizinphysikern in Europa

Aktivitäten internationaler Organisationen (z. B. WHO, IAEA) mit Bedeutung für die Medizinphysik

Darüberhinaus ist auch eine „Standortbestimmung“ der Medizinischen Physik, vor allem auch im Rahmen der neuen europäischen Studiensysteme („Bologna“) notwendig geworden. Der Vortragende ist als Präsident der OGMP in diese Aktivitäten eingebunden und kann auf die genannten Punkte ausführlicher eingehen

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MBU-2: HS 415, Do, 9 Sept, 15:00 Uhr

Dynamik und Dosimetrie der Radonfolgeproduktablagerung auf der Haut

H. Lettner, W. Hofmann, H. Tempfer, A. Schober und A. Hubmer

Abteilung für Physik und Biophysik, [email protected] für Materialwissenschaften und Physik, Universität Salzburg A 5020 Salzburg, Austria

In der Radontherapie werden in zunehmendem Maße die Deposition von Radonzerfallsprodukten (Rnp) auf der Haut und deren mögliche therapeutische Wirkung in Betracht gezogen. In beiden angewendeten Therapieformen, der Exposition in einer Radonatmosphäre und der Anwendung von Wannenbädern mit radonhältigem Thermalwasser, kommt es zur Ablagerung von Radonzerfalls-produkten auf der Haut, die aber entsprechend den unterschiedlichen physikalischen Bedingungen zu unterschiedlichen Aktivitätsverhältnissen der Rnp auf der Haut führen, die für die Dosimetrie von nicht unerheblicher Bedeutung sind. Unter den gegebenen Therapiebedingungen sind in der Radonatmosphäre die Rnp generell im Ungleichgewicht mit dem Radongas. Durch die Dynamik des Aerosolwachstums wird Po-218 als mobilstes Rnp schneller auf der Haut abgelagert als die nachfolgenden Rnp, was letztendlich zu einer Aktivitäts-konzentration in der Reihe Po-218 > Pb-214 > Po-214 führt. Deponierte Rnp verbleiben auf der Haut und wandern in tiefere Hautschichten, wo beim Zerfall auch die biologisch relevanten Langerhansschen Zellen von den Alphateilchen erreicht werden können. Im Unterschied zu einer Radonatmosphäre sind unter den Bedingungen der Exposition in den Radonwannenbädern die Rnp weitgehend im Gleichgewicht mit Radon. Nach den experimentellen Ergebnissen desorbiert ein großer Teil der Rnp nach der Ablagerung wieder von der Haut. Dieses Verhalten führt zu einem Aktivitätsverhältnis der Rnp, das in etwa den Verhältnissen der Halbwertszeiten entspricht. Ausführliche experimentelle Untersuchungen der Exposition in einer Radon-atmosphäre und in Wannenbädern unter den therapeutischen Gegebenheiten in der Gasteiner Radontherapie haben gezeigt, dass die Deposition von Rnp auf der Haut zu erheblichen Aktivitätskonzentrationen führt. Selbst unter den Bedingungen der Exposition in einer Radonatmosphäre überwiegt die Deposition auf der Haut die Deposition in der Lunge um mindestens eine Größenordnung. Infolge des Eindringens der Rnp in tiefere Hautschichten erreicht ein Teil der deponierten Alphaenergie biologisch relevante Bereiche, die eine nähere Betrachtung dieser Situation nahe legt. Die Ergebnisse der experimentellen Untersuchungen und die Berechnungen zur Dosimetrie werden in dieser Arbeit vorgestellt.

References [1] H. Tempfer, W. Hofmann, A. Schober, H. Lettner, A. L. Dinu. „Deposition of

radon progeny on skin surfaces and resulting radiation doses in radon therapy”, Radiat Environ Biophys, 49, 249–259. (2010).

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MBU-3: HS 415, Do, 9 Sept, 15:15 Uhr

Characterizing the Effects of Combinations of Visible-Infrared Laser Beam and Blue/Red-Led-Arrays on Albican Candida and Pityriasis Versicolor Distruction

R. Penjweini 1, 2 , F. Mohajer 3, A. Geranmayeh 2, K. W. Kratky 1, and S. Saghafi 2,4

1 Physics of Physiological Processes, Faculty of Physics, University of Vienna, Austria, [email protected]

2 Biophotonics Laboratory, Plasma-Physics Research Center, Research Science Campus, IAU, Tehran, Iran

3 Physics Department, North-Tehran Campus, IAU, Tehran, Iran 4 Department of Bioelectronics, Institute of Solid State Electronics, Vienna

University of Technology, Vienna, Austria, [email protected]

This study presents the effects of combinations of non-ionizing coherent and non-coherent visible-near infrared light on destruction of Albican Candida and Pityriasis versicolor in vivo. Considering the absorption spectra of Candida obtained using Carry-500-scans spectrophotometer, a second harmonics of Nd:Yag laser (100mW/ 3mm spot-size), a red diode laser (120 mW/ 8mm spot-size), an infrared diode laser ( 150mW/ 6mm spot size), an array of 24 Blue-LED (72mW ) and array of 20 Red-LED-Array (80 mw) have been chosen as illuminating sources. During the irradiation process, candida infections received 6, 10 and 14 J/cm2 laser light incident doses (ID) of 532nm, 660nm and 980nm coherent beams, respectively. Additionally, it received 2 J/cm2 ID from LED arrays (420< <470nm and 624< <660nm). Patients with Albican Candida had 7 sessions of illuminations and the patients with Pityriasis versicolor had 15 sessions of illuminations (Fig.1). In addition to the ability of photons to produce electronic excitations in chromophores, light can induce a wave-like alternating electric field in Cndidas that interacts with polar structures. It produces dipole transitions at different cellular and biochemical processes [1-2]. Furthermore, the Reactive Oxygen Species (ROS) production that is cytotoxic can be increased due to this processes and it can kill the Candida cells when the concentration becomes sufficiently high. The method is accurate, highly reproducible and relatively inexpensive [3].

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Fig. 1: The effects of combination of coherent (visible/infrared) and LED on Candida

References [1] Amat, A., “The electric field induced by light can explain cellular responses to

electromagnetic energy: A hypothesis of mechanism”. Journal of photochemistry and photobiology B: Biology 82, 152-160 (2006)

[2] Chang, WH., “Effect of pulse- burst electromagnetic field stimulation on osteoblast cell activities”, Bioelectromagnetic 25 (6), 457-465 (2004).

[3] Luksiene, Z., “Photodynamic inactivation of harmful and pathogenic microorganisms”. Vet Med Zootech, 26(48), 58-60 (2004).

128

MBU-4: HS 415, Do, 9 Sept, 15:50 Uhr

Variability of Aerosol Optical Depth over the Karachi mega city using MODIS and AERONET data

K. Alam1 and T. Blaschke1

1Department of Geography and Geology, University of Salzburg, Hellbrunnerstrasse 34, Salzburg 5020, Austria E-mail: [email protected]

Atmospheric aerosols play an important role in the energy balance of the earth-atmosphere system. The aerosol concentration is increasing in various locations especially in Asia because of growing population and economy, urbanization, and industrialization. The population of the Karachi mega city in Pakistan is currently around 13 million and is expected to reach 25 million by 2020. The rapid growth of the city which has resulted in unregulated development and inappropriate land-use changes has also resulted in an estimated 50% of the population living in unplanned, poorly serviced and heavily polluted informal settlements. The lack of an effective and efficient mass transit system means leads to increasing numbers of vehicles on ever-more congested roads leading to increased air pollution. In this research we examined the spatial and temporal variations of aerosol particles over Karachi using Moderate Resolution Imaging Spectroradiometer (MODIS) data from the Terra satellite and ground based data using Aerosol Robotic Network (AERONET) for the year 2009. We used the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model for trajectory analysis to reveal the origins of air masses, with the aim of understanding these spatial and temporal variabilities in aerosol concentrations. Our analysis reveals that maximum values of aerosol optical depth (AOD) are found in the summer season both for satellite and ground based observations. We also examined the relationship between AOD and water vapour (WV) in order to understand the hygroscopic nature of atmospheric aerosols. The analyses exhibit strong positive correlations (greater than 0.85) between AOD and WV. We observed that WV is also higher during the summer, matching the increase in AOD and indicating the possibility of hygroscopic growth of aerosols.

References [1] Kuniyal, C.J., Thakur, A., Thakur, K.H., Sharma, S., Pant, P., Rawat, S.P.,

and Moorthy, K.K. Aerosol optical depths at Mohal-Kullu in the northwestern Indian Himalayan high altitude station during ICARB. J. Earth Syst. Sci, 118, 41-48 (2009).

[2] Prasad .K.A, Singh .R.P, and Ashbindu, S. Variability of Aerosol Optical Depth over Indian Subcontinent using MODIS data. Journal of Indian Society of Remote Sensing, Vol. 32, No. 4 (2004)

129

MBU-5: HS 415, Do, 9 Sept, 16:05 Uhr

Lung Dosimetry for Inhaled Long-Lived Radionuclides and Radon Progeny

M. Hussain1,2 , R. Winker-Heil1 and W. Hofmann1

1Division of Physics and Biophysics, University of Salzburg, 5020 Salzburg, Austria 2 Directorate General of Safety, 44000, Islamabad, Pakistan

Doses delivered to the bronchial and alveolar regions of the lung following inhalation of long-lived radionuclides depend on the initial deposition pattern as well as on bronchial and alveolar clearance mechanisms. Up to now, the stochastic lung dosimetry model IDEAL-DOSE considers deposition in the whole bronchial and alveolar airway system, while clearance was restricted to bronchial airways. However, for the inhaled of long-lived radionuclides (LLR), alveolar clearance has also to be considered for the calculations of alveolar as well as the bronchial doses. Thus the primary objectives of this study were (i) to develop stochastic clearance model in the alveolar region, (ii) to calculate total lung dose contribution from LLR in addition to short-lived Rn-222 decay progeny. Transport rates of insoluble particles in individual respiratory airways, alveolar ducts and sacs are based on the average transport rates proposed for the revision of the ICRP Human Respiratory Tract Model (HRTM). Based on average transport rates, particle residence times are calculated stochastically in the alveolar region. Retention curves for the alveolar region, illustrating the joint effect of deposition and clearance, were compared with available experimental data in human volunteers, revealing good agreement between experimental data and modeling predictions. Dose calculations for bronchial and alveolar airways were performed for inhaled radon progeny and 238U decay products for a reference uranium ore activity concentration. The results obtained indicate that LLR cleared from the alveolar region are the primary contributor to bronchial doses, being higher by factors of 2-6 than the dose contributed by radionuclides directly deposited in the bronchial tree. Comparison of LLR doses to that of short-live radon progeny predicts that long lived alpha emitters in uranium mines can deliver up to 5 percent of the doses allowed from the short lived radon daughters.

References [1] Baily, M.R.,“Updating the ICRP human respiratory tract model“, Radiation

protection dosimetry 127(1-4), 31-34 (2007) [2] Harley, N.H., “Alpha dose from long-lived emitters in underground mines“,

Occupational Radiation Safety in Mining 2, 518-522 (1985) [3] Marsh, J.W., “Dosimetric models used in the alpha risk project to quantify

exposure of uranium miners to radon gas and its progeny“, Radiation Protection Dosimetry 130(1), 101-106 (2008)

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MBU-6: HS 415, Do, 9 Sept, 16:20 Uhr

Reconstruction of the Airborne Emissions by Inverse Dispersion Modelling and Generation of Synthetic Emission Data by a Monte Carlo Approach

G. Schauberger1, M. Piringer2, W. Knauder2, E. Petz2, K. Bauman-Stanzer2

and E. Petz2

1 Molecular Physiology and Biophysics, University of Veterinary Medicine Vienna, Veterinärplatz 1, A 1210 Vienna, Austria, [email protected] Central Institute for Meteorology and Geodynamics, Department of Environmental Meteorology, Hohe Warte 38, A 1190 Vienna, Austria, [email protected]

The determination of the emission flow of pollution sources can often not be done directly. This can be the case if the geometry of the source is complicated, a direct measurement will not be tolerated by the company, or a retrospective assessment of the emission flow seems appropriate. In the absence of emission measurements, the emission flow of the source can be assessed by inverse dispersion modelling using ambient concentration measurements and meteorological parameters as input. The dispersion model used is the Austrian regulatory Gauss model. This method is applied to a thermal treatment plant. Seven chemical species (butyl acetate, benzene, ethyl acetate, toluene, m/p-xylene, o-xylene and -pinene), are identified as odour-relevant and measured over a period of 1½ years in the prevailing wind direction leeward of the plant. The selected log-normal cumulative distribution function (CDF) shows a good fit to the empirical CDF of all seven species. The resulting odour emission is calculated by adding the odour emission of all single species, using the individual odour threshold concentration. The odour emission flow shows a good agreement showing the applicability of the chosen approach to re-calculate odour emissions from measured concentrations of chemical species. The emission data are available however only for the wind directions for which the measuring station is leeward of the plant. Using a Monte-Carlo model, the dataset was completed also for wind directions for which no ambient concentration measurements were available. The parameters for the Monte-Carlo model were derived by the statistical analysis of the dataset. The main input variables which determine the emission of the plant are the intermittence factor, air temperature, wind velocity, time of the day and day of the week, which describe the working process of the plant. For the model evaluation the ambient concentrations calculated by the synthetic emission data were compared to the measured ambient concentrations. After calibrating the Monte-Carlo model, the expected values and the variances are in good agreement with the empirical data.

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MBU-7: HS 415, Do, 9 Sept, 16:35 Uhr

Altersabschätzung alpiner Kryokonite mit Hilfe natürlicher und künstlicher Radionuklide

T. Wilflinger1, A. Hubmer1 und H. Lettner1

1Universität Salzburg, Abteilung Physik und Biophysik, Fachbereich für Materialforschung und Physik, Hellbrunnerstrasse 34, A-5020 Salzburg, [email protected]

Als Kryokonite (aus dem Griechischen: kalter Staub) werden auf Eisfeldern durch Windverfrachtung abgelagerte Sedimente bezeichnet, die sich durch teilweise extrem hohe Radionuklidkonzentrationen auszeichnen. In Kryokoniten vom Stubacher Sonnblickkees, einem temperierten Gletscher in den Hohen Tauern, konnten die künstlichen Isotope 137Cs, 134Cs, 238Pu, 239+240Pu, 90Sr, 241Am, 60Co, 125Sb, 154Eu, und 207Bi identifiziert werden. Unter den natürlichen Isotopen waren unter anderem 210Pb, 7Be, und 40K erfassbar. Künstliche Nuklide in der Umwelt entstammen in Zentraleuropa zwei Quellen, die sich nach ihrer Isotopenzusammensetzung und in ihren Radionuklidverhältnissen unterscheiden lassen. Die erste Quelle ist der Global Fallout, der in den oberirdischen Waffentests Ende der Fünfziger bzw. Anfang der Sechzigerjahre seinen Höhepunkt erreichte. Die zweite Quelle ist der Eintrag aus dem Reaktorunfall von Tschernobyl, der ab der ersten Maiwoche 1986 zu einer enormen Deposition künstlicher Radionuklide führte. Die Unterteilung und Alterszuordnung der Kryokonite erfolgt vorwiegend durch Cäsium- und Plutoniumisotope bzw. deren Radionuklidverhältnisse. Diese Methode wurde bereits an Kryokoniten des Hallstätter Gletschers erfolgreich angewendet [1]. Die Bestimmung der Pu-Isotope ist jedoch generell sehr zeit- und arbeitsaufwendig und in sehr alten oder sehr jungen Kryokoniten praktisch unmöglich. Hier bietet sich als weitere Möglichkeit die Altersabschätzung mit dem natürlichen Radionuklid 210Pb an, das als Radonzerfallsprodukt in annähernd konstanten jährlichen Eintragsraten deponiert wird. An den Kryokoniten des Stubacher Sonnblickkees werden die verschiedenen Möglichkeiten der Altersabschätzung mit Radionukliden gezeigt.

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MBU-8: HS 415, Do, 9 Sept, 16:50 Uhr

Waterfall-Related Aerosol Inventory

P.Madl1, P.Kolarž2, A.Hartl3, M.Gaisberger3 and W.Hofmann1

1University of Salzburg, Material Research and Physics, Hellbrunnerstr. 34 A-5020 SBG, [email protected] of Physics, Pregrevica 118, RS-11080 Belgrade, [email protected] Medical University, Institute for Physiology and Pathophysiology, Strubergasse 21. 11, A-5020 SBG, arnulf [email protected],[email protected]

The current study investigated the distributions of ionic-clusters and aerosols originating from waterfalls. The 10 day measurement campaign was performed with three portable Gerdien condensers (air-ion detectors) to monitor air-ion concentrations [1] and a Scanning Mobility Particle sizer (SMPS), along with an optical particle counter (OPC) to determine the size distribution of aerosols. The size spectra covered in each measurement ranged from 0.9 to 350nm for the negative ion concentration. Determination of negative charges using the SMPS covered the full range, whereas the positive complement was restricted to a size window of 0.9 to 2 nm and was determined by the detection principle of the SMPS. Using the fully-fitted SMPS (with the neutralizer attached to the DMA) made it possible to monitor aerosol distributions in the size window ranging from 5.5 to 350 nm. In combination with the OPC, it was possible to extend the upper threshold up to 2 m.The investigation revealed a distinct aerosol distribution in proximity to the falls along with a soaring concentration of negative ions in the lowest size range below 10 nm. As expected, off-site control measurements used to monitor background ion- and particle concentrations prompted significantly different signatures. The increased concentration of negative intermediate ions is assumed to be due to the so-called waterfall effect [2], in which auto-ionization due to friction, fragmentation and charge-separation mechanisms cause free charges inside water droplets. Fluctuation in charges and their mobility yield free ions when a droplet collides with an obstacle. Aerosol spectra on the other hand showed a distinct “wash-out-effect” of otherwise specific aerosol distribution in the absence of a waterfall, whereas aerosol concentrations – especially in the lower size range below 100nm – are elevated as condensation and agglomeration effects are suppressed due to the cooler microclimatic conditions near the falls.

References [1] Kolarz P.M., Filipovi D.M., Marinkovi B.P., “Daily variations of indoor air-ion

and radon concentrations”, Applied Radiation and Isotopes 67, 2062–2067 (2009)

[2] Laakso L., Hirsikko A., Gronholm T., Kulmala M., Luts A. and Parts T.E. “Waterfalls as sources of small charged aerosol particles”, Atmos. Chem. Phys. 7, 2271–2275 (2007)

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8.9 OGD – Oberflächen, Grenzflächen und Dünne Schichten

Donnerstag - Thursday 9 September 2010 / Blauer Hörsaal


Parallel Session OGD

Zeit Time



9:00 - 9:40 Keynote:

Frank Stefan Tautz (FZ Jülich)

Metal-Molecule Contacts: From Adsorption to Charge Transport

9:40 - 10:00 Margareta Wagner(Univ. Graz)

Digging for the dewetting reconstruction at the organic interface:

A low temperature STM study of 6P on Cu(110)

10:00 - 10:20 Lidong Sun (Univ. Linz)

Thermally activated inversion of pentacene/para-sexiphenyl heterostructures

on Cu(110)

10:20 - 10:40 Alexander J. Fleming(Univ. Graz)

Photoemission electron microscopy of the temperature dependent pre-nucleation

dynamics of sexiphenyl molecules deposited on Cu (110)

10:40 - 11:00 Thorsten Wagner(Univ. Linz)

Growth of -6T on flat and vicinal Ag(110) surfaces


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Donnerstag - Thursday 9 September 2010 / Blauer Hörsaal



Zeit Time



13:30 - 14:10 Keynote:

Michael Schmid(TU Wien)

Metal diffusion and growth studied by STM

14:10 - 14:30 Stefanie Rund (Univ. Linz)

Charge exchange of He+ ions on aluminium surfaces

14:30 - 14:50 Erminald Bertel(Univ. Innsbruck)

Low-dimensional systems on metal surfaces:Electronic structure and phase transitions

14:50 - 15:10 Mariella Denk (Univ. Linz)

The effect of postgrowth oxygen exposure on the magnetic properties of Ni

on the Cu-CuO stripe phase

15:10 - 15:30 Yuri Suchorski (TU Wien)

Reaction kinetics via PEEM imaging: laterally-resolved studies of catalytic CO oxidation

on single grains of polycrystalline Pd


15:50 - 16:10 Günther

Weidlinger (Univ. Linz)

2D gas - condensed phase transition of pentacene on Cu(110)-(2 1)O

16:10 - 16:30 Johannes Gall (Univ. Linz)

Lattice Gas Monte Carlo Simulations of Pentacene on Cu(110) - (2 1)O

16:30 - 16:50 Roland Resel (TU Graz)

Structure and stability of a quinquethiophene based self-assembled monolayer

16:50 - 17:10 Clemens

Simbrunner (Univ. Linz)

Epitaxial growth of sexi-thiophene and para-hexaphenyl on sheet silicates

17:10 - 17:30 Christoph Reichl (AIT, Wien)

Experimental study on icing and condensation on structured plates and glasses

in low speed flows

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17:30 - 17:50 Ines Haynl (Univ. Graz)

Cryo atomic force microscopy: A new way to investigate elastomeric samples

17:50 - 18:10 Jahreshauptversammlung

des Fachausschusses OGD OGD annual general assembly

Freitag - Friday 10 September 2010 / Blauer Hörsaal



Zeit Time



9:00 - 9:20 Luca Gragnaniello(Univ. Graz) Ordered Arrays of NiOx nanoclusters

9:20 - 9:40 Igor Beinik (MU Leoben)

Complementary study of ZnO nanorods by scanning probe microscopy

9:40 - 10:00 Franz J. Schmied(MU Leoben) Tricking AFM to its limit

10:00 - 10:20 Michael Mayrhofer-

Reinhartshuber(TU Graz)

Structure and Phonon Dispersion of Bi(111) from He Atom Scattering

10:20 - 10:40 Daniel Primetzhofer(Univ. Linz)

Trace element quantification in high-resolution Rutherford backscattering spectrometry

10:40 - 11:00 Mujeeb Ullah (Univ. Linz)

Meyer-Neldel rule and disorder in organic devices

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OGD-1: Blauer Hörsaal, Do, 9 Sept, 09:00 Uhr

Metal-Molecule Contacts: From Adsorption to Charge Transport

F.S. Tautz

Institut für Bio-und Nanosysteme, Forschungszentrum Jülich, 52425 Jülich, Germany, and Jülich Aachen Research Alliance � Fundamentals of Future Information Technology [email protected]

Highly ordered monolayers and thin films of electrically active molecules on single-crystal metal surfaces are excellent model systems for metal-molecule contacts. They can be used to study fundamental properties of metal-molecule contacts, employing a wide range of surface analytical techniques. In this talk I will give examples of our recent work regarding structure and bonding at the organic-metal interface [1-3], interface energetics [4], and precision measurements of current transport through metal-adsorbed molecules using an STM tip [5].

The adsorption of large organic molecules on metal surfaces is often affected by a sizeable contribution of van der Waals attraction to the interaction energy. This makes theoretical simulations challenging. Precise measurements of structural parameters of adsorbed molecules are therefore important as benchmarks for novel simulation approaches [1]. On the other hand, with a universal theoretical description still missing, empirical rules, such as the scaling of the adsorption height with the substrate work function that was observed for PTCDA on noble metal surfaces, provide important guidelines for our understanding [2]. Apart from the molecule-substrate interaction, intermolecular interactions play an important role. For example, networks of hydrogen bonds can influence the internal geometry of adsorbed molecules and their adsorption height [3], whereas intermolecular polarization screening can influence their electronic structure [4]. Adsorbed molecules on single-crystal surfaces are also an excellent starting point for precise and well-controlled charge transport experiments through individual molecules, because with an STM they can be contacted at a defined position within the molecule [5]. In this way, the influence of electron correlation on quantum transport can be studied.

Finally, we show that if an STM is equipped with a single D2 molecule that is confined in the STM junction [6], Pauli repulsion is probed and can be used to record images of unprecedented resolution [7]. The chemical structure of molecules and intermolecular bonds become visible.

References [1] Mercurio, G. et al., “Structure and energetics of azobenzene at Ag(111):

Benchmarking semi-empirical dispersion correction approaches”, Phys. Rev. Lett. 104, 036102 (2010).

[2] Kilian, L. et al., “Role of intermolecular interactions on the electronic and geometric structure of a large -conjugated molecule adsorbed on a metal

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surface”, Phys. Rev. Lett. 100, 136103 (2008). [3] Hauschild, A. et al., “Normal-incidence x-ray standing-wave determination of

the adsorption geometry of PTCDA on Ag(111): Comparison of the ordered room-temperature and disordered low-temperature phases”, Phys. Rev. B 81, 125432 (2010).

[4] Soubatch, S. et al., “Site-specific polarization screening in organic thin films”, Phys. Rev. Lett. 102, 177405 (2009).

[5] Temirov, R. et al., “Kondo effect by controlled cleavage of single-molecule contact”, Nanotechnology 19, 065401 (2008).

[6] Temirov, R. et al., “A novel method achieving ultra-high geometrical resolution in scanning tunnelling microscopy”, New J Phys. 10, 053012 (2008).

[7] Weiss, C. et al., “Imaging Pauli repulsion in scanning tunneling microscopy”, Phys. Rev. Lett. 2010, accepted.


Digging for the Dewetting Reconstruction at the Organic Interface: A low Temperature STM Ttudy of 6P on Cu(110)

M. Wagner, S. Berkebile, A. Fleming, T. Ules, G. Koller, F. P. Netzerand M. G. Ramsey

Institute of Physics, Surface and Interface Physics, Karl-Franzens University Graz, A-8010 Graz, Austria, [email protected]

From studies of the sexiphenyl (6P) growth on Cu(110) with Photoemission Electron Microscopy (PEEM), enhanced 1-dimensional diffusion has been observed. We have postulated this to be a result of a 3rd layer dewetting reconstruction [1,2]. In this work with the STM at cryogenic temperatures the nature of this reconstruction has been explored. Moreover, by applying molecular manipulation we have been able to “dig” down through several molecular layers to the Cu interface. The initial 3rd layer molecules which we argued to provide channels for the observed 1-D diffusion are observed as one-dimensional strings of twisted molecules. The regular spacing of the strings suggests a reconstruction. Removing these strings and 2nd

layer molecules reveals that the highly ordered and densely packed 1st monolayer of planar flat lying molecules on Cu(110) has been reconstructed with edge-on planar molecules incorporated into it. Thus the reconstruction is not an organic surface reconstruction per se but a reconstruction at the molecule-Cu interface. This work has been supported by the by the Austrian Science Foundation (FWF) within the National Research Network “Interface Controlled and Functionalized Organic Films” and the ERC Advanced Grant “SEPON”.

References [1] Fleming A. et al., “PEEM of the Temperature Dependent Pre-nucleation

Dynamics of Sexiphenyl Molecules Deposited on Cu(110)”, Phys. Chem.

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Chem. Phys., submitted [2] Fleming, A. et al., “Pre-Nucleation Dynamics of Organic Molecule Self-

Assembly Investigated by PEEM“, Omicron, Result of the month 06/2010


Thermally Activated Inversion of Pentacene/Para-Sexiphenyl Heterostructures on Cu(110)

L.D. Sun1, C.Y. Liu1,2, D. Queteschiner1, G. Weidlinger1, X. Fu2, X.T. Hu2

and P. Zeppenfeld1

1Institute of Experimental Physics, Johannes Kepler University Linz Altenbergerstr. 69, A-4040 Linz (Austria), [email protected] Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Weijin Road, 300072 Tianjin, (China)

Thermally activated inversion of pentacene/para-sexiphenyl (p-6P) molecular heterostructures on the Cu(110) surface is studied with the combination of reflectance difference spectroscopy (RDS) and scanning tunnelling microscopy (STM). The heterostructures are formed by deposition of a sub-monolayer of pentacene on top of a p-6P buffer layer with a thickness of up to 3 monolayers on Cu(110) at 15 K. When the sample temperature is raised, these heterostructures invert, with pentacene molecules diffusing through the p-6P buffer layer and getting in direct contact with the substrate. The observed inversion is due to the energy minimization of the multilayer system and is thus of general importance for organic heterostructures. The onset temperature of the inversion increases with the number of p-6P monolayers indicating a corresponding rise of the energetic barrier for the inter-layer diffusion.


Photoemission Electron Microscopy of the Temperature Dependent Pre-nucleation Dynamics of Sexiphenyl Molecules Deposited on Cu (110)

A. J. Fleming, S. Berkebile, F. P. Netzer and M. G. Ramsey

Surface and Interface Physics, Karl-Franzens Universität Graz, Universitätsplatz 5, 8010 Graz, Austria

[email protected]

The pre-nucleation dynamics of sexiphenyl (6P) molecules deposited in-situ on Cu (110) is investigated by photoemission electron microscopy (PEEM) in ultrahigh vacuum. PEEM, in threshold mode, is used to monitor precisely in real-time a) the

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amount deposited, b) layer filling by 6P molecules, c) dynamic surface density redistributions during layer filling and d) critical surface density spontaneously induced meta-stable layer de-wetting [1]. It is by studying this crucial pre-nucleation deposition period that the requirements for critical nucleation of 6P, can be understood. A numerical simulation of PEEM image photoemission intensity variations with time is shown to help determine pre-nucleation layer filling mechanisms for various growth temperatures. Comparison with data previously obtained from static techniques, such as STM and LEED, together with dynamic data from PEEM of 6P deposited on Cu (110) 2 x 1 – O [2] enable the 6P nucleation processes to be elucidated from PEEM. Furthermore, data obtained during post-nucleation deposition times allows nucleation and molecular binding energies to be obtained from temperature dependent trends of nucleation and desorption rates, respectively.

References [1] Omicron June 2010 Result of the Month, Omicron Nanotechnology,

www.omicron.de [2] A J Fleming, F P Netzer, M G Ramsey, J. Phys: Condens. Matter 21 (2009)

445003


Growth of -6T on Flat and Vicinal Ag(110) Surfaces

T. Wagner1,2, D. R. Fritz1 and P. Zeppelfeld1

1Johannes Kepler University Linz, Institute for Experimental Physics, Atomic Physics and Surface Science Division, Altenbergerstr. 69, 4040 Linz 2Email: [email protected]

For the growth of -sexithiophene ( -6T) on a variety of substrate surfaces a Stranski-Krastanov growth is reported: After the completion of a wetting layer, 3D crystallites are formed. It is known that the crystallographic structure of the crystallites is strongly influenced by the substrate: Ivanco et al.[1] have changed the orientation of the molecules from flat lying to upright standing by inducing defects to the surface by ion bombardment. To determine the influence of the substrate morphology on the structure of an organic film we have studied the growth of -6Ton a flat Ag(110) and stepped Ag(441) crystal surface by means of photoelectron-emission microscopy (PEEM) and scanning tunnelling microscopy (STM). The PEEM technique allows studying the growth in situ and in real time. The coverage dependent intensity curves recorded on Ag(110) and Ag(441) with an Hg lamp (4.9 eV) are almost identical: Although the ionisation potential of the -6T is higher than the energy of the photons, a uniform increase of the PEEM intensity is found upon the deposition of the first layer because of a lowering of the work function at the metal-organic interface. Additional layers on top do not contribute to the electron emission but scatter electrons emitted from the metal-organic interface.

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Therefore, the PEEM intensity decreases again for the second and further layers. Only if one uses photon sources with higher energies like a D2 (6.4 eV) or a He lamp (21.2 eV) one can excite photoelectrons from the organic layer itself. For the same sample temperature, larger but fewer crystallites are found on the flat Ag(110) surface as compared to the Ag(441) surface where the step edges act as nucleation centres. PEEM spectroscopy further reveals that besides the wetting layer there are two types of crystallites present on the Ag(110) surface: Needle like crystallites consisting of flat lying molecules and platelets, in which the molecules are nearly upright standing. For the initial growth of -6T on Ag(110) we find two orientations of the molecules in the first layer by STM: They arrange parallel to the [001] and [1-10] direction while no long range order is found. For the second layer of -6T on the Ag(110) surface, the molecules align in chains with their long axis parallel to the [001] direction. For the Ag(441) surface, the orientation of the molecules is exclusively parallel to the [1-10] direction in the first and second layer, i.e., the molecules align parallel to the silver steps. In addition step bunching and faceting of the substrate surface occurs due to the adsorption of -6T.

References [1] J. Ivanco, T. Haber, J.R. Krenn, F.P. Netzer, R. Resel, M.G. Ramsey,

“Sexithiophene films on ordered and disordered TiO2(110) surfaces: Electronic, structural and morphological properties”, Surface Science 601,178-187 (2007)


Metal Diffusion and Growth Studied By STM

M. Schmid

Institut für Angewandte Physik, TU Wien, 1040 Wien, Austria. [email protected]

The structure and morphology of thin films grown by deposition on solid surfaces strongly depend on two elementary processes, diffusion and nucleation. While these processes are very rapid at typical conditions used for thin film growth, we can study them in detail by scanning tunneling microscopy at low temperatures and submonolayer coverages. Even though such studies have been conducted for about two decades [1], surprising results are still possible in this field. The first part of the talk will be devoted to nucleation theory applied to metal homoepitaxy by pulsed laser deposition (PLD). PLD differs from thermal evaporation (physical vapor deposition) by the high instantaneous flux of particles arriving at the surface and by high-energy ions (30 ... 300 eV) impinging on the surface, both leading to increased nucleation densities [2]. STM shows defects created by the high-energy ions, which is also of interest for other deposition

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methods like ion-beam assisted deposition (IBAD) and sputter deposition, where the effects of fast ions are not easily accessible to experiment. In the second part, new effects in metal diffusion and nucleation will be presented. We will show that the long-range forces acting on adatoms play an important role that has been often ignored in such studies. By watching adatom diffusion of Co and Pt on Pt(111), we found a barrier for formation of Co ad-dimers, while Pt adatoms easily form dimers. Density functional theory (DFT) calculations show that the barrier is not related to the magnetic moment of Co atoms. Nucleation of small Pt clusters shows another unexpected phenomenon: We found a large number of linear chains, with lengths of up to 9 atoms. This result cannot be explained by a simple diffusion-limited-aggregation model, and we suggest that the strain field of the substrate plays an important role, steering some of the diffusing adatoms towards the ends of linear clusters. As a further ingredient to this phenomenon, a study of the binding energies of Pt adatom clusters by DFT shows that bonding of such clusters does not follow the rule of "higher coordination means stronger bonding". Instead, short linear chains are bound more strongly than more compact configurations. The reason for this phenomenon is strong directional bonding via dz2-like orbitals, a mechanism previously proposed for binding between the late transition metals and oxygen atoms and explaining the preference for O atoms at opposite sides of a metal atom [3].

References

[1] Michely, T, Krug J, “Islands, mounds and atoms – patterns and processes in crystal growth far from equilibrium“, Springer Berlin 2004

[2] Schmid M. et al., “High island densities in pulsed laser deposition: causes and implications”, Phys. Rev. Lett. 103, 076101 (2009).

[3] Lundgren, E. et al., “Surface oxides on close-packed surfaces of late transition metals”, J. Phys.: Condens. Matter 18, R481 (2006).


Charge Exchange of He+ Ions on Aluminium Surfaces

S. Rund*, D. Primetzhofer, S.N. Markin and P. Bauer

Institut für Experimentalphysik, Johannes Kepler Universitaet Linz, A-4040 Linz

INTRODUCTION The efficient neutralization of low energy ions scattered from surface atoms is the basis of the superior surface sensitivity in Low-Energy Ion Scattering (LEIS) [1]. Below a reionization threshold Eth non-local Auger neutralization (AN) is the only relevant charge exchange process and permits to describe the ion fraction P+ by

)exp()0

))((exp( vvdttzP c

A with the Auger transition rate A, the

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0,0 0,5 1,0 1,5 2,0 2,5 3,00

10

20

30

40

50

60

70 3He - Al/Si4He - Al/Si4He - Cu [S. Markin]

FWH

M, e

V

kE0, keV 0,20,0 5,0x10-6 1,0x10-5 1,5x10-5 2,0x10-5 2,5x10-5

0,01

0,1

1

4He3He

Ion

frac

tion

P+

1/v , s/m

vc = 2.2x10 5

m/s

He Al(111)

characteristic velocity vc and the velocity of the projectile perpendicular to the surface v�. At primary energies E > Eth local charge exchange processes, i.e. collision induced reionization (CIR) and collision induced neutralization (CIN) start to contribute.

EXPERIMENTAL RESULTS An Al(111) single crystalline surface and polycrystalline aluminium have been investigated by electrostatic analyzer low-energy ion scattering (ESA-LEIS) using ³He+ and 4He+ ions. Experiments were performed with the set up MiniMobis which permits precise analysis of the energy of ions backscattered in single collision from surface atoms at very low primary energies (down to 280 eV).

Fig. 1: FWHM of the detected ion intensity backscattered from Al (squares) and Cu (triangles).

The reionization threshold Eth was deduced from the energy dependence of the FWHM of the ion peak. For Cu where AN dominates up to 2 keV E~E is observed [2], as expected for an ESA. In contrast, the FWHM of the ion peak in spectra recorded for He+ and Al exhibits a significant broadening at 0.2– 1 keV (see Fig. 1). Since reionization leads to an energy loss (~ 15 – 20 eV) the increasing contribution of CIR will also increase the FWHM and additionally shift the ion peak to smaller energies. Extrapolating data points of 4He and 3He scattered from Al/Si at higher energies one obtains Eth = 200 eV. The experimentally deduced P+ is depicted in Fig. 2. Although all data presented are recorded at E > Eth, very good agreement with a fit according to Eq. 1 is found. No significant deviation is observed even for the highest energies, pointing to a qualitatively different neutralisation behaviour than for Cu were a strong deviation was observed for E > Eth [2].

References [1] H.H. Brongersma, M. Draxler, M. de Ridder, P. Bauer, Surf. Sci. Rep. 62

(2007) 63. [2] M. Draxler, R. Gruber, H.H. Brongersma, P. Bauer, Phys. Rev. Lett. 89 (2002)

263201

Fig. 2: Experimentally deduced ion fraction P+ of He+ scattered from Al(111)

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Low-Dimensional Systems on Metal Surfaces: Electronic Structure and Phase Transitions

E. Bertel1, M. Cordin1, P. Amann1, A. Menzel1, and J. Redinger2

1Institute of Physical Chemistry, University of Innsbruck, A-6020 Innsbruck, Austria; [email protected]

2Institute of Applied Physics, Vienna University of Technology, A-1010 Wien, Austria

Lowering the dimensionality of electronic systems increases electronic correlation and often leads to instabilities caused by competing electronic interactions. In the ideal case of one-dimensional (1D) systems, the Fermi liquid paradigm breaks down in favour of Luttinger liquid behaviour. The phase diagram of real (quasi-1D) systems depends on the relative strength of interactions and is in most cases only partially understood [1]. The (110) surfaces of Pt and Pd fcc single crystals feature strongly anisotropic electronic surface resonances and are therefore well-suited templates to prepare quasi-1D systems [2]. We investigate these systems by angle-resolved UV photoemission and scanning tunnelling microscopy. Although correlation is expected to be weak on a metal surface, a strongly enhanced electron-phonon interaction is observed in the present low-D systems. Competition between inter-adsorbate interactions and charge density wave formation in the substrate leads to an anomalous phase diagram on both metal surfaces [3-4]. Furthermore, tuning the electronic surface structure via suitable adsorbates seems to result in a ferromagnetic surface layer on the Pd(110) surface. Such a layer has a profound effect on the transmission and reflection of spin polarised electrons. Hence a reversible switching of a surface layer into a ferromagnetic state could have attractive applications in spintronics.

References [1] Bertel, E. and A. Menzel, Nanostructured surfaces: Dimensionally

constrained electrons and correlation, in The Oxford Handbook of Nanoscience and Technology, A.V. Narlikar and Y.Y. Fu, Editors., 308-354, Oxford University Press (2010)

[2] Dona, E., et al., Nanostructured metal surfaces as quasi-one-dimensional model systems. Applied Surface Science 254(14), 4230-4237 (2008)

[3] Dona, E., et al., Fluctuations and phase separation in a quasi-one-dimensional system. Physical Review Letters 98(18) 186101-4 (2007)

[4] Cordin, M., et al., Phase transitions driven by competing interactions in low-dimensional systems: A microscopic view. submitted (2010).

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The Effect of Postgrowth Oxygen Exposure on the Magnetic Properties of Ni on the Cu-CuO Stripe Phase

M. Denk, R. Denk, M. Hohage, L. Sun, and P. Zeppenfeld

Institut für Experimentalphysik, Johannes Kepler Universität Linz, A-4040 Linz, Austria; E-Mail: [email protected]

The magnetism and morphology of thin Ni films deposited on clean and oxygen covered Cu(110) has been studied. In the latter case oxygen acts as a surfactant modifying the Ni growth. Scanning Tunneling Microscopy (STM), as well as Reflectance Difference Spectroscopy (RDS) are used to characterise the sample properties. The sensitivity of the RDS to the polar Magneto-Optic Kerr Effect has been exploited (RD-MOKE). Contrary to growth on pristine Cu(110), thin Ni films on oxygen covered Cu(110)-(2x1)O show a spin reorientation transition from in-plane to out-of-plane magnetisation at 9 ML Ni coverage [1], [2].For Ni films evaporated on the Cu-CuO stripe phase, which consists of a periodic array of (2x1) reconstructed CuO stripes separated by bare Cu, the magnetic easy axis lies completely in-plane up to a coverage of 22.5 ML. Exceeding this coverage, a small remanent magnetisation component pointing out-of-plane evolves. Upon postgrowth oxygen exposure the Ni film becomes completely out-of-plane magnetised and the out-of-plane remanence and coercive field strongly increase during exposure. STM images show a fully (2x1)O reconstructed surface after the oxygen exposure, but no morphological changes of the Ni film. We thus conclude that the oxygen strongly modifies the surface magnetic anisotropy.

References [1] Th. Herrmann, K. Lüdge, W. Richter, K. G. Georgarakis, P. Poulopoulos,

R. Nünthel, J. Lindner, M. Wahl and N. Esser, Phys. Rev. B, 73, p. 134408 (2006)

[2] R. Denk, M. Hohage and P. Zeppenfeld, Phys. Rev. B, 79, p. 073407 (2009)

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Reaction Kinetics via PEEM Imaging: Laterally-Resolved Studies of Catalytic CO Oxidation on Single Grains of Polycrystalline Pd

Y Suchorski1, Ch. Spiel1, D. Vogel1,2, W. Drachsel1, R. Schlögl2, G. Rupprechter1

1Institute of Materials Chemistry, Vienna University of Technology, A-1210 Vienna, Austria 2Fritz-Haber-Institut der Max-Planck-Gesellschaft, D-14195 Berlin, Germany

To describe the catalyst behavior, studies of reaction kinetics are often summarized in a so-called kinetic phase diagram, in which the regions of monostability, bistability and temporal oscillations are displayed for various external parameters. Such kinetic studies are mainly performed by mass-spectroscopy (MS) and suffer, for heterogeneous systems, from spatial averaging. As a result, the obtained kinetic phase diagram presents a superposition of reactive properties of different surface regions which may differ significantly from each other, e.g. for metal-oxide systems [1]. However, kinetic transitions in a catalytic reaction can not only be pursued by MS techniques but also by in situ visualization of the reaction using modern surface microscopies, such as PEEM (photoemission electron microscopy, [2,3]). However, corresponding diagrams are generally created by spatial averaging of the PEEM data, similar as for MS, and the main advantage of PEEM, namely the possibility to obtain laterally-resolved information, was not yet exploited for locally-resolved kinetic studies. Recently, we have demonstrated for the first time that kinetic phase diagrams can also be obtained for individual �m-sized domains of a polycrystalline Pt foil, by processing the video-PEEM data obtained during catalytic CO oxidation [3]. In present contribution we extend this approach to polycrystalline Pd foil. We were able to obtain the kinetic phase diagrams for the [100]-, [110]- and [111]-oriented domains, present on the polycrystalline Pd foil. The differences between the Pt and Pd domains of the same orientation with respect to CO oxidation and effects of reaction-coupling between the domains are discussed.

References [1] Y. Suchorski, R. Wrobel, S. Becker, H. Weiss, J. Phys. Chem. C, 112 (2008)

50, and refs. therein. [2] G. Ertl, Nobel Prize Lecture, Ang. Chemie Int. Ed. 47 (2008) 3524; M.

Berdau, G.G. Yelenin, A. Karpowicz, M. Ehsasi, K. Christmann, J.H. Block, J. Chem. Phys. 110

(1999) 11551. [3] Y. Suchorski, Ch. Spiel, D. Vogel, W. Drachsel, R. Schlögl, G. Rupprechter,

2010, submitted.

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2D gas - Condensed Phase Transition of Pentacene on Cu(110)-(2x1)O

G. Weidlinger1, C.Y. Liu1,2, D. Queteschiner1, L.D. Sun1,X. Fu2, X.T. Hu2 and P. Zeppenfeld1

1Institute of Experimental Physics, Johannes Kepler University Linz, Altenbergerstr. 69, A-4040 Linz (Austria), [email protected] State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Weijin Road, 300072 Tianjin, (China)

The adsorption of pentacene on Cu(110)-(2x1)O in the sub-monolayer regime was studied in-situ using reflectance difference spectroscopy (RDS). In a wide temperature range, the RD signal recorded as a function of pentacene coverage reveals a change of the preferential orientation of the long molecular axis from the Cu[1-10] at low coverage to the Cu[001] direction at high coverage. The observation is explained by a phase transition from a 2D gas phase to a 2D condensed phase accompanied by the switching of the molecular orientation. From the variation of the critical coverage of the phase transition as a function of substrate temperate, the interaction energy of pentacene in the condensed phase on Cu(110)-(2x1) is determined to be about 84 meV.


Lattice Gas Monte Carlo Simulations of Pentacene on Cu(110) - (2 1)O

J. Gall1, M. Hohage1, C. Liu1, D. Queteschiner1, G.Weidlinger1, L. Sun1,and P. Zeppenfeld1

1Institute of Experimental Physics, Johannes Kepler University, Linz, Austria. [email protected]

A reversible two-dimensional phase transition of pentacene sub-monolayer films on the Cu(110) - (2 1)O reconstructed surface has been observed. Several Monte Carlo (MC) and Kinetic Monte Carlo (KMC) simulations of a lattice gas model have been performed to understand the behavior of the system. The combination of MC and KMC simulations allows investigating the role of kinetic processes during the phase transition. In the simulations different interaction models have been investigated. In particular, we find that the characteristics of the phase transition strongly depend on the anisotropy of the lateral interactions. The simulation results are compared to recent RDS (reflectance difference spectroscopy) and STM (scanning tunneling microscopy) experiments as well as to theoretical results from Onsager [1].

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References [1] Onsager, L., Crystal statistics. I. A two-dimensional model with an order-

disorder transition. Phys. Rev., 65 (1944), 117.


Structure and Stability of A Quinquethiophene Based Self-Assembled Monolayer

H.-G. Flesch1, A. Moser1, O. Werzer1, E.C.P. Smits2,3,4, S. G. J. Mathijssen3,F. Gholamrezaie2,3, H.J. Wondergem3, S.A. Ponomarenko5, D.-M. Smilgies6,G. Hlawacek7, Q. Shen7, C. Teichert7, P. Puschnig8, R. Resel1, and D.M. de Leeuw2,3

1Institute of Solid State Physics, Graz University of Technology, Petersgasse 16, 8010 Graz, Austria2 Molecular Electronics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands 3 Philips Research Laboratories, High Tech Campus 4, 5656 AE Eindhoven, The Netherlands 4 Dutch Polymer Institute, PO Box 902, 5600 AX Eindhoven, The Netherlands 5 Enikolopov Institute of Synthetic Polymer Materials, Russian Academy of Sciences, Profsoyuznaya 70, 117393 Moscow, Russia 6 CHESS Centre, Cornell University, 14850 Ithaca, New York, USA 7 Institute of Physics, University of Leoben, Franz Josef Strasse 18, 8700 Leoben, Austria 8 Chair of Atomistic Modelling and Design of Materials, University of Leoben, Franz Josef Strasse 18, 8700 Leoben, Austria

In organic electronics the use of self-assembly is one promising approach to high yield and reproducibility in device fabrication. Quinquethiophene SAMFETs have been built with a yield of one. Accordingly integrated circuits like bit generators could be realized [1]. Two elements of the molecule are crucial for the monolayer formation and the electronic properties. First the monofunctional anchoring group which avoids uncontrolled polymerization and second the high tendency of quinquethiophene to form nice lateral crystallographic order. This highly ordered system is responsible for the charge transport properties within the self assembled monolayer. Electronic and crystallographic properties have been investigated for the submonolayer state [2]. It is the first system reported with a long range ordered self-assembled monolayer formed on SiO2.

The formation of monolayers has been followed by atomic force microscopy and x-ray reflectivity. However a slight tendency to form multilayers has been found by AFM. The in-plane order of the monolayer has been investigated by grazing incidence in-plane diffraction which reveals three nicely pronounced Bragg rods already in the submonolayer state. From the in-plane order a herringbone packing of the molecules within a rectangular unit cell is deduced. DFT calculations

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have been performed to calculate the packing of the molecules within the unit cell determined by the experiments. Two different phases can be seen in the crystal ordering, one consisting of upright standing molecules and another one where the molecules are tilted 13° towards the b-axis of the unit cell. A transition between these phases is forced by temperature treatment of the SAM. In the pristine state right after preparation in the solution the molecules are standing upright. After the first temperature treatment (330K) they are found to be already tilted. At elevated temperatures however the molecules are always standing fully upright. The crystallographic order is lost above 520K, followed by a dramatic decrease in layer thickness at 620K and complete desorption above 880K.

References [1] E.C.P. Smits et al., “Bottom-up organic integrated circuits”, Nature 455,

956-959 (2008) [2] S.G.J. Mathijssen et al., “Monolayer coverage and channel length set the

mobility in self-assembled monolayer field-effect transistors“,Nature Nanotechnology 4, 674 - 680 (2009)


Epitaxial Growth of Sexi-Thiophene and Para-Hexaphenyl on Sheet Silicates

C. Simbrunner1, G. Hernandez-Sosa1, D. Nabok2, M. Oehzelt3, T. Djuric4,R. Resel4, L. Romaner2, P. Puschnig2, C. Ambrosch-Draxl2, I. Salzmann5,G. Schwabegger1, I. Watzinger1 and H. Sitter1

1Institute of semiconductor and solid state physics, JKU Linz, 4040 Linz, [email protected] of Atomistic Modelling and Design of Materials, MU Leoben, 8700 Leoben 3Institute of Experimental Physics, JKU Linz, 4040 Linz 4Institute of Solid State Physics, TU Graz, 8010 Graz 5Institut für Physik, Humboldt-Universität zu Berlin, D-12489 Berlin

Organic molecules provide several advantages in the fabrication of nanostructures, as they combine high luminescence efficiency, flexible spectroscopic properties and easy processing with the possibility for controlled, self-assembled growth [1]. Consequently during the last years strong efforts have been undertaken to study the growth of thiophenes and phenylenes on various substrates, motivated by their affinity to form highly crystalline organic nano-needles [2]. In particular, it turned out that oligo-p-phenylenes in combination with muscovite mica as growth substrate represent a prominent and outstanding material combination, forming a stable molecular building block [3]. It has been demonstrated that their ability for generating long, parallel-aligned nanofibers provides a proper fundament for several applications like waveguiding and lasing [4]. Motivated by this promising criterion the growth of para-hexaphenyl (p-6P) on muscovite mica has been

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investigated intensely [5,6] and, as a consequence, the discussed material system is well understood concerning morphological, structural and optical properties. Contrary, the growth of phenylenes and thiophenes on phlogopite mica is rarely analysed with respect to structural investigations. This contribution is focused on a structural determination and analysis concerning the epitaxial relationship between para-hexaphenyl/sexi-thiophene and muscovite/phlogopite mica substrates. Based on x-ray diffraction experiments, a clear picture concerning crystal phase, contact plane, azimuthal orientation and molecular alignment can be drawn for all four material systems. All results are verified by Fourier analysis deduced from morphological investigations which are based on atomic force microscopy and optical microscopy leading to a consistent picture. Based on this experimental evidence and results from force field simulations for the adsorption of single molecules on mica substrates, an growth model is presented being able to explain the epitaxial alignment of organic molecules on muscovite mica substrates without the presence of dipole fields.

References [1] Balzer, F.; Rubahn, H.-G. “Growth Control and Optics of Organic

Nanoaggregates”,Adv. Funct. Mat. 15, 17 (2005)

[2] Koller, G.; Berkebile, S.; Krenn, J. R.; Tzvetkov, G.; Hlawacek, G.; Lengyel, O.; Netzer, F. P.; Teichert, C.; Resel, R.; Ramsey, M. G., “Oriented Sexiphenyl Single Crystal Nanoneedles on TiO2 (110)”, Adv. Mat. 16, 2159 (2004).

[3] Schiek, M.; Balzer, F.; Al-Shamery, K.; Lützen, A.; Rubahn, H.-G., “ Light-emitting organic nanoaggregates from functionalized p-quaterphenylenes”,Soft Matter 4, 277 (2008)

[4] Quochi, F, “Random lasers based on organic epitaxial nanofibers”, J. Opt. 12, 024003 (2010)

[5] Resel R., Haber T., Lengyel O., Sitter H., Balzer F. and Rubahn H.-G., „Origins for epitaxial order of sexiphenyl crystals on muscovite (001)“, Surf. Interface Anal. 41, 764 (2009)

[6] Hernandez-Sosa G., Simbrunner C. and Sitter H., “Growth and optical properties of -sexithiopene doped para-sexiphenyl nanofibers”, Appl. Phys. Lett. 95, 013306 (2009)

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Experimental Study on Icing and Condensation on Structured Plates and Glasses in Low Speed Flows

C. Reichl1, G. J. Pauschenwein1, B. Windholz1, C. Zauner1, M. Chouiki2,R. Schöftner2 and M. Monsberger1

1Austrian Institute of Technology, Energy Department, Giefinggasse 3, A-1210 Wien, Österreich, [email protected]

2Profactor GmbH, Functional Surfaces and Nanostructures, Im Statgut A2, 4407 Steyr-Gleink, Austria

Icing and condensation are critical phase change processes occurring in heat exchanger applications as well as in solar thermal collector physics. Ice growth in heat exchangers lead to blocking of air flow and reduce the efficiency, droplets and ice can have a significant impact on solar production and dropping liquids can lead to a considerable deterioration of chemically treated metal sheets often found in those devices. Therefore it is of utmost importance to understand condensation and the onset of icing and its dependence on relative humidity, flow speed, turbulent structures in the flow and both the surrounding and the plate temperature. In this contribution we focus on the promising application of microstructures and the utilization of different glass surfaces. An experimental facility to investigate icing and condensation in low speed flows using thermography and image capturing methods is presented. The facility is characterized with respect to local thermodynamic and flow properties using various experimental techniques including CTA, 3D-PIV, surface temperature sensors and heat sphere probes. The experimental setup and the most important results are summarized in the first part. We will include results from thermocouple and pt100 difference measurements. Then we will present a computational analysis method to gain insight into the data of the image capturing during the underlying phase change processes. This methodology is finally applied to plates and glasses exhibiting different surface structures. The results will add to the understanding of condensation and icing processes on micro structured plates and glasses and provide the base for numerical simulations, which will be capable of predicting onset-times, film- and ice-thickness estimations leading to energy efficient and cost-effective designs.

References [1] Lee K., Jhee S., Yang D. (2003), Prediction of the frost formation on a cold

flat surface, International Journal of Heat and Mass Transfer 46(20), 3789-3796.

[2] Reichl, Ch. et al., Experimental studies on the icing�onset on plates in low speed flows, IIR 1st Conference on Sustainable Refrigeration and Heat Pump Technology, Stockholm, May 2010

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Cryo Atomic Force Microscopy: A New Way to Investigate Elastomeric Samples

I. Haynl1, A. E. Efimov2, N. B. Matsko1 and W. Grogger1

1Graz Centre for Electron Microscopy (ZFE) & Institute for Electron Microscopy and Fine Structure Research (FELMI) of Graz University of Technology, Steyrergasse 17, 8010 Graz, Austria, [email protected] Scan Technology Ltd., Zavodskaya st. 7, Dolgoprudnyy, Moscow region, 141700, Russia

The sectioning of samples at low temperatures down to -190°C is known as cryo-ultramicrotomy. Combined with an atomic force microscope (AFM) operating at the same temperature this is a new method that offers great possibilities to investigate soft materials, e.g. polymers. We are encouraged to share the results of AFM measurements, done at room temperature and under cryo conditions, to point out new opportunities in material characterization. One crucial influence on the quality of measurements is sample preparation by ultramicrotomy. Since we use elastomers, ultramicrotomy has to be operated under cryo conditions due to the fact that soft polymers usually have a glass transition temperature significantly below 0°C and most elastomers and their composites can only be sectioned at temperatures 10 to 20 degrees lower than their glass transition temperature [1]. By comparing block faces after sectioning, done at room temperature and under cryo conditions it is easy to see how the quality of the surfaces and therefore the AFM image quality is improved. Preparation of a sample with the ultramicrotome and measuring the bulk surface right after, both under cryo conditions, lead to new observations. Measuring at room temperature would imply heating up of the sample and therefore changes in the internal structure. It is now the first time that we are able to observe polymers in the cryo state and prevent the samples from changes between sectioning and measuring. We would like to discuss these results by looking at experiments done using different elastomeric polymer blends.

References [1] Ivanov, D. A. and Magonov, S. N., “Atomic Force Microscopy Studies of

Semicrystalline Polymers at Variable Temperature”, (Reiter, G. and Sommer J.-U., (Eds)), Lecture notes in physics 606, 98-130, Springer-Verlag Berlin Heidelberg (2003)

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OGD-17: Blauer Hörsaal, Fr, 10 Sept, 09:00 Uhr

Ordered Arrays of NiOx Nanoclusters

L.Gragnaniello*, T. Ma, S. Surnev and F. P. Netzer

Institut für Physik, Oberflächen- und Grenzflächenphysik, Karl-Franzens Universität Graz, Universitätsplatz 5, A-8010 Graz, Austria *[email protected]

The fabrication of ordered assemblies of nanoparticles (NPs) with uniform size of a few nanometers presents one of the most exciting challenges in nanoscience, since novel physical and chemical properties can be expected due to their reduced dimensionality and due to interface and proximity effects. While promising results have been achieved in the selfassembly of ordered metal and semiconductor NPs, only little progress has been made until now in the 2D organization of metal oxide nanoclusters, although potential applications are foreseen in the fields of catalysis and magnetic applications. In particular, nickel oxide NPs are promising because of their versatile catalytic properties [1] and because of their spin glass magnetic behaviour [2]. Also, partially oxidized nickel clusters may be of great interest, if a Ni-NiO core-shell configuration is achieved, since exchange bias phenomena may evolve [3]. Here we report the successful fabrication of ordered arrays of NiOx nanoclusters, achieved by post-oxidation of highly ordered nickel NPs supported on an ultrathin alumina template. The alumina substrate (2 monolayers thick) has been preparedby controlled high-temperature oxidation of a Ni3Al(111) single crystal surface. The complex AlOx structure [4] provides an ordered lattice of hole sites, which act as anchoring sites for the Ni NPs condensing them into a regular superlattice with 4.1 nm dimensions. The regular arrangement of the clusters as well as their narrow size distribution have been probed by Scanning Tunneling Microscopy and LEED. The progressive oxidation of the Ni nanoclusters has been studied as a function of the cluster size and the thermodynamic oxidation variables by high-resolution XPS with use of synchrotron radiation (MAX-Lab, Lund, Sweden). We find that a morphology conserving oxidation procedure is possible and that the resulting NiOx NPs form a highly regular superlattice.

Work supported by the ERC Advanced Grant SEPON.

References [1] Wei W., et al., Journal of Hazardous Materials 168, 838–842 (2009);

Li J., et. al., Environmental Science & Technology 42 (16), 6224–6229 (2008)

[2] Bisht V., Rajeev K.P., J. Phys.: Condens. Matter 22, 016003 (5p) (2010) [3] Johnston-Peck A.C. et al., ACSNano 3 (5), 1077-1084 (2009) [4] Schmid M., et al., Physical Review Letters 99, 196104 (4p) (2007)

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Complementary Study of ZnO nanorods by Scanning Probe Microscopy

I. Beinik1, M. Kratzer1, G. Brauer2, W. Anwand3, X. Chen4, Y. F. Hsu4,A.B. Djuriši 4 and C. Teichert1

1 Institut für Physik, Montanuniversität Leoben, Austria, [email protected] für Ionenstrahlphysik und Materialforschung, Forschungszentrum Dresden-Rossendorf, Germany 3Institut für Strahlenphysik, Forschungszentrum Dresden-Rossendorf, Germany 4Department of Physics, University of Hong Kong, P.R. China

ZnO exhibits a wide spectrum of morphologies on the nano- and meso- scale [1] which are of prospects to become functional [2,3]. Nanorods (NRs) made of ZnO are of particular interest for application in UV photosensors [4] and solar cells [5]. Recently, ZnO NRs have been suggested for the conversion of mechanical to electrical energy [6]. These applications require a detailed insight into the electrical, opto-electrical, and electro-mechanical properties of the ZnO NRs. One of the most appropriate tools to achieve this purpose is conductive atomic force microscopy (C-AFM). C-AFM has been proven to be suitable in characterization of thin dielectric films [7], low-dimensional semiconductor structures [8] and electroceramics [9]. The opto-electrical and electro-mechanical properties of the NRs can be studied using photoconductive AFM (PC-AFM) and piezoresponse force microscopy (PFM), respectively.

Here, we present a C-AFM study of individual ZnO nanorods [10] grown by hydrothermal synthesis [1,2] and thermal evaporation [3]. Both types of rods have been grown on Si (100) and ITO substrates. Measurements were performed in air and nitrogen atmosphere at variable temperatures. Current-voltage characterization on individual upright standing nanorods revealed a characteristic similar to that of a p-n diode. Along with the C-AFM studies, nanorods were also characterized by means of PFM and PC-AFM. Detailed discussion of the opto- and piezo-electrical properties is based on local I-V curves measured under- and without illumination, as well as on the PFM images recorded from specific areas.

References 1. L.E. Greene, et al., Nano Lett. 5, 1231 (2005). 2. K.H. Tam, C.K. Cheung, Y.H. Leung, A.B. Djuriši , C.C. Ling, C.D. Beling,

S. Fung, W.M. Kwok, Y.H. Leung, W.K. Chan, D.L. Phillips, L. Ding, W.K. Ge, J. Phys. Chem. B 110, 20865 (2006).

3. Y.F. Hsu, Y.Y. Xi, A.B. Djuriši , W.K. Chan, Appl. Phys. Lett. 92, 133507 (2008).

4. L. Luo, Y. Zhang, S. S. Mao and L. Lin, Sensors and Actuators A 127, 201 (2006).

5. I. Gonzalez-Valls and M. Lira-Cantu, Energy Environ. Sci. 2, 19 (2009).6. Z.L. Wang, J. Song, Science 312, 242 (2006).

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7. S. Kremmer, H. Wurmbauer, C. Teichert, G. Tallarida, S. Spiga, C. Wiemer and M. Fanciulli, J. Appl. Phys. 97, 074315 (2005).

8. P. Tejedor, L. Díez-Merino, I. Beinik, C. Teichert, Appl. Phys. Lett. 95,123103 (2009).

9. M. Schloffer, C. Teichert, P. Supancic, A. Andreev, Y. Hou, Z. Wang, J. Eur. Cer. Soc 30, 1761 (2010).

10. G. Brauer, et al., Phys. Status Solidi C 6, 2556 (2009).


Tricking AFM to Its Limit

F. J. Schmied1,3, R. Schennach2,3 and C. Teichert1,3

1Institute of Physics, University of Leoben, Franz Josef Str. 18, A 8700 Leoben 2Institute of Solid State Physics, Graz University of Technology, Petersgasse 16/2, 8010 Graz 3CD-Laboratory for Surface Chemical and Physical Fundamentals of Paper Strength, Graz University of Technology, Petersgasse 16/2, 8010 Graz

Atomic Force Microscopy (AFM) is an appropriate tool to investigate structures on the nanometer scale with various surface sensitive techniques, such as Conductive AFM (CAFM), Friction Force Microscopy (FFM) and Phase Imaging which is based on Tapping Mode AFM. These methods are well known and are standard applications for AFM, especially the latter one. Measurements on the micrometer scale are harder to access by AFM due to restrictions of the piezo movement in xy-direction as well as for rough structures in z-direction. Limitations of the applied force are based on the cantilever stiffness. Usually, the cantilever stiffness for different AFM application ranges from 0.01 μN to 50 μN. In this work, a method is presented that deals with cantilever stiffness between 300 to 400 μN. Limitations and solutions are presented to trick a conventional AFM and push the system to its limit. First measurements of forces up to allmost 1 mN are presented on single pulp fibers.

Supported by Mondi and the Christian Doppler Research Society, Vienna, Austria.E-mail of corresponding author: [email protected]

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Structure and Phonon Dispersionof Bi(111) from He Atom Scattering

M. Mayrhofer-Reinhartshuber1, A Tamtögl1, W E Ernst1 and K H Rieder2

1Institute of Experimental Physics, Graz University of Technology, Graz, Austria 2Empa, Swiss Laboratories for Materials & Research, Zurich, Switzerland

As a material with significant differences in bulk and surface properties, bismuth (Bi) has attracted renewed interest among researchers. The presence of metallic surface states is unusual for a bulk semimetal and provides the playground for ideas related to the electronic response of the surface and even the possibility of two-dimensional superconductivity [1]. With regard to phonon states, calculations of the bulk phonon dispersion are consistent with experimental data only when spin-orbit interaction is taken into account [2]. Recently, squeezed bulk phonon states were measured with femtosecond x-ray diffraction [3]. In contrast to phonons in the bulk and the electronic surface structure nothing is known about the surface phonons of the Bi(111) surface. They are in a low energy region of meV and therefore not accessible with satisfying resolution for most scattering techniques, but with experiments using helium atom scattering (HAS) surface phonons can be investigated successfully. We have used elastic and inelastic HAS to study the Bi(111) surface therefore we are able to present the first report on phonon creation and annihilation events on this surface. The surface phonon dispersion relation has been determined from measured time-of-flight spectra of inelastically scattered He atoms. The obtained group velocity lies somewhat above the bulk group velocity. Elastic HAS experiments reveal rather large diffraction peaks in comparison to other metals. A first comparison between theoretical (eikonal approximation, GR-method) and measured diffraction peak intensities yields a surface charge density corrugation of 16% of the surface unit cell. This value is surprisingly large since the reported metallic character of the Bi(111) surface would imply a nearly flat corrugation. The observed surface corrugation and the steep slope in the phonon dispersion may both point to the important role of the strong covalent bonds at the surface.

References [1] Hofmann P 2006 Prog. Surf. Sci. 81 191[2] Díaz-Sánchez L E, Romero A H and Gonze X 2007 Phys. Rev. B 76 104302 [3] Johnson S L et al. 2009 Phys. Rev. Lett. 102 175503

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Trace Element Quantification in High-Resolution Rutherford Backscattering Spectrometry

D. Primetzhofer*, and P. Bauer

Institut für Experimentalphysik, Johannes Kepler Universitaet Linz, A-4040 Linz, Austria

Rutherford backscattering spectrometry (RBS) is a versatile tool for analysis of composition and thickness of nm-films. Low concentrations of heavy elements in light matrices, e.g. transition metals in C, can easily be detected. In the present work a multi-element organic compound, i.e. human blood was investigated to show the potential of high-resolution RBS for quantification of trace elements. This is of special interest also for other ion beam based techniques (e.g. SIMS, PIXE) have been successfully applied for organic materials [1,2]

EXPERIMENT AND RESULTS The experiments were performed employing the AN-700 accelerator at the Johannes Kepler University of Linz, which can provide monoenergetic beams of H,D and He ions with up to 700 keV primary energy. A high resolution LN2 cooled surface barrier detector was used to record the spectra of backscattered projectiles [3]. The blood sample was prepared in the following way: a droplet of human blood was deposited on a graphite sample, dried in air and subsequently transferred to the target chamber together with a graphite reference target.

ExperimentSimulatedCNONaMgPSClKCaFeZnSeRb

Channel12512011511010510095908580757065605550

Cou

nts

1

10

100

1 000

10 000

100 110 120 130 140 150 160 170 180 190 200 210 220 230 240

Energy [keV]

Figure 1: RBS spectrum for 250 keV D+ scattered from a film of human blood deposited on graphite. Shown are the experiment and a fit obtained by SIMNRA [4].

RBS spectra were recorded for 250 keV D+ ions scattered from the blood film and the reference sample. Simulations of the RBS spectra were performed using the program SIMNRA [4]. For the graphite reference target elements other than C were below a concentration of 1.5 at%. From the shape of the RBS spectrum of the

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organic sample it can be ascertained that the substrate signal is not visible. It was possible to identify at least 10 chemical elements with high accuracy, as can be seen in Fig.1. For instance, the concentration of Fe was determined to 350 +/- 10 ppm equivalent to 400 mg/L in perfect agreement with standard blood test values. The detection limit for elements with atomic number higher than Fe is found to be below 20 ppm. Note that it would be possible to resolve a concentration gradient within the film by high-resolution RBS.

References [1] A. Benninghoven, and W.K. Sichtermann, Analytical Chemistry 50 (1978) 1180 [2] R. Lobinski, C. Moulin, and R. Ortega, Biochimie 88 (2006) 1591 [3] M. Geretschläger, Nucl. Instr. and Meth. B 204 (1983) 479 [4] M. Mayer, Application of accelerators in research and industry 475 (1999) 541


Meyer-Neldel Rule and Disorder in Organic Devices

M. Ullah1, I. I. Fishchuk2, A. K. Kadashchuk3,4, A. Pivrikas5, P. Stadler5,A. Kharchenko6, C. Simbruner1, N. S. Sariciftci5 and H.Sitter1

E-mail: [email protected]

1Institute of Semiconductor and Solid State Physics, JKU Linz, Austria. 2Institute for Nuclear Research, National Academy of Sciences of Ukraine, ProspectNauky 47,03680 Kyiv, Ukraine 3IMEC, Kapeldreef 75, B-3001 Heverlee, Belgium 4Institute of Physics, National Academy of Sciences of Ukraine, Prospect Nauky 46,03028 Kyiv, Ukraine 5Linz Institute of Organic solar cells, LIOS, JKU Linz, Austria. 6PANalytical B.V., 7600 AA Almelo, The Netherlands

The performance of organic material based field effect transistors (OFETs) depends on the field effect mobility which, now-a-days, approaches to 20 cm2 V 1 s 1 with short molecules, and 0.2 cm2 V 1 s 1 with polymers. Fullerene “C60” is known as n-type organic semiconductor materials with its symmetric structure, low ionization potential and high mobilities depending on different morphologies of C60 films (0.6-6cm2V-1s-1) [1-2]. In the present work we fabricated the OFETs using different substrate temperature to grow different morphologies of C60 films by Hot Wall Epitaxy system. Atomic Force Microscopy images and XRD results showed increasing grain size with increasing substrate temperature. A shift in field effect mobility was observed for different OFETs with different morphologies of C60 films with increasing grain size. The temperature dependence of the field effect mobility was determined in the accumulation regime of the device characteristics in the temperature range from 300K to 80K. A change from an activated charge carrier transport to a non-activated transport at lower temperatures was observed. The temperature dependence of these devices showed different Arrhenius activation

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energies. More over these C60 based OFETs follow the empirical relation between the Arrhenius activation energy and the mobility prefactor named as Meyer-Neldel Rule [2-3]. A shift in characteristic Meyer-Neldel energy, which can be described as energetic disorder parameter of the material, was observed with changing C60 film morphology [3]. As a consequence, the Meyer-Neldel energy can be considered as material quality criterium, characterizing the width of energetic disorder [5]while the carrier mobility depends on many other parameters not only on the degree of disorder in the material.

References [1] Mujeeb Ullah, D. M. Taylor, R. Schwödiauer, H. Sitter, S. Bauer, N. S.

Sariciftci and Th. B. Singh, Journal of Applied Physics, 106, 114505 (2009). [2] Mujeeb Ullah, T.B. Singh, H. Sitter, N.S. Sariciftci, Applied Physics A,

Materials Science & Processing 97 (2009), 521. [3] Mujeeb Ullah, I. I. Fishchuk, A. Kadashchuk, P. Stadler, A. Pivrikas,

C. Simbrunner, V. N. Poroshin, N. S. Sariciftci, and H. Sitter, Appl. Phy. Lett. 96,213306 (2010).

[4] I. I. Fishchuk, A. K. Kadashchuk, J. Genoe, Mujeeb Ullah, H. Sitter, Th. B. Singh, N. S. Sariciftci, and H. Bässler, Phys. Rev. B 81, 045202 (2010).

[5] A. Pivrikas, Mujeeb Ullah, Th. B. Singh, C. Simbrunner, G. Matt, H. Sitter and N. S. Sariciftci, Organic Electronics submitted.

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9. POSTER

9.1 AMP – Atome, Moleküle, Quantenphysik und Plasmen

POS-AMP-1 Hypergeometric Function Representation of Relativistic Transition Matrix Elements for Hydrogenic Atoms and their Contributions to the Lamb Shift

Nach Haupteingang links / Left of main entrance, Di, 7. Sept., 15:30 Uhr

G. Adam1, A. V. Soldatov2, J. Seke1 and M. Polak1

1lnstitut für Theoretische Physik, TU Wien, Wiedner Hauptstraße 8-10/136,A 1040 Wien, Austria [email protected]. Steklov Mathematical Institute, Dept. of Mechanics, 8, Gubkina str. 119991 Moscow, Russian [email protected]

By using the plane-wave expansion for the electromagnetic-field vector potential, relativistic bound-bound, bound-unbound and unbound-unbound transition matrix elements for hydrogenic atoms are expressed universally in terms of hypergeometric functions of the type 2F1 in such a way that these functions only depend on the absolute value of the wave vector |k| and the dependence on angular variables of the wave vector is totally factored out and only comes through functional multipliers built of spherical harmonics. By applying the obtained formulae, these transition matrix elements can be evaluated analytically and numerically with arbitrarily high precision. The newfound representation for the matrix elements is very convenient for direct numerical evaluation of the Lamb shift, especially at the second perturbational order, because its separable structure allows for direct analytical integration over the angular variables of the wave vector for the contribution to the shift from each matrix element, no matter bound-bound or bound-unbound, thus resulting in only one one-dimensional integration to be evaluated numerically. Universality, conciseness and strict reliance on functions, already built in the standard computational packages contributes to making this matrix elements representation preferable for programming of computationally efficient algorithms in various QED-related problems.

Acknowledgements This work was supported by the Dr. Anton Oelzelt-Newinsche Stiftung of the Austrian Academy of Sciences, by the RAS research program “Mathematical Problems of Nonlinear Dynamics” and by the RFBR grant No 09-01-00086-a.

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POS-AMP-2 Investigation of Hyperfine Structures of Pr II Lines in the Region 572-579 nm by Collinear Laser Ion Beam Spectroscopy


N. Akhtar1, 2, H. Hühnermann1,3 and L. Windholz*, 1

1 Institute of Experimental Physics, Petersgasse 16, Technical University Graz, Austria 2 Optics Labs P. O. Box 1021, Nilore Islamabad, Pakistan 3 Department of Physics, University of Marburg, Germany * E-mail: [email protected]

In this work we have performed Doppler free hyperfine structure investigations of Pr II, by the method of collinear laser ion beam spectroscopy. The hyperfine structure (hfs) of a fine structure level is caused by electromagnetic interaction between orbiting and spinning electrons and the nucleus. We have used praseodymium powder in a surface ion source of Johnson type to produce praseodymium ions. Due to the high density of low lying thermally populated metastable levels in praseodymium, many transitions can be investigated. The ion beam is accelerated to 20 kV and mass is separated by a 90° magnet. A collimated ion beam is obtained in the light collection region. The excitation source is a ring dye laser pumped by an Argon ion laser operated with Rhodamine 6G. In the interaction chamber, Doppler tuning is carried out to investigate transitions in the region of 572 nm to 579 nm. A photon counting method is used to record the laser induced fluorescence. Magnetic dipole interaction constants A and the electric-quadrupole interaction constants B of the involved levels have been determined using a fit program and the results are found to be in good agreement with published values.

POS-AMP-3 Hyperfine Structure in the Line 5855 Å of 137Ba II Investigated by Collinear Laser Ion Beam Spectroscopy


N. Akhtar1, 2, N. Anjum1, 2, H. Hühnermann1,3, C. Neureiter and L. Windholz* 1

1 Institute of Experimental Physics, Petersgasse 16, Technical University Graz, Austria 2 Optics Labs P. O. Box 1021, Nilore Islamabad, Pakistan 3 Department of Physics, University of Marburg, Germany * E-mail: [email protected]

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The mass separator MARS-II, originally installed at the university of Marburg/Germany, had been extensively used to investigate hyperfine structures and isotopic shifts of different elements such as cesium, xenon, samarium, promethium, lanthanum, barium, europium etc. This MARS-II system has been transferred to Technical University Graz, in the Institute of Experimental physics and is now producing first results. In a gas discharge, atom/ions have random velocity distribution resulting in a Doppler broadened line shape. In collinear ion beam spectroscopy, all ions have approximately uniform velocity; therefore a nearly Doppler free spectrum is obtained. Barium is used to calibrate the system. The ions were produced from Barium Nitrate in a Johnson type surface ion source. These ions are accelerated to 20 kV and then, a mass separator magnet separates different barium isotopes. Singly ionized barium has two low lying metastable d-levels which are populated during the production of ions. In the interaction chamber, Doppler tuning is carried out to investigate the transition between 5d 2D3/2 6p 2P°3/2. A ring dye laser pumped by an Argon ion laser is used as excitation source in the spectral range of Rhodamine 6G. Detecting the laser induced fluorescence by a photon counting method a well resolved hyperfine structure of ionized barium-137 has been observed. The recorded hyperfine structure is fitted using a fit program and the magnetic dipole interaction constant A and the electric-quadrupole interaction constant B of the combining levels are determined. The A, B values are found to be in good agreement with the literature values.

POS-AMP-4 Measurements of Hyperfine Structure Constants of Pr II by Using High Resolution Collinear Laser Ion Beam Spectroscopy


N. Anjum1, 2, N. Akhtar1, 2, H. Hühnermann1,3 and L. Windholz*,1

1 Institute of Experimental Physics, Petersgasse 16, Technical University Graz, Austria 2 Optics Labs. P. O. Box 1021, Nilore Islamabad, Pakistan 3 Department of Physics, University of Marburg, Germany *E-mail: [email protected]

We have used collinear laser ion beam spectroscopy (CLIBS) for Doppler free investigations of hyperfine structure (hfs) of Praseodymium ions (Pr II). Due to velocity bunching effect and selective excitation process CLIBS is a very powerful technique for the precision study of hfs. Hyperfine structure is caused by the electromagnetic interaction between the nucleus and orbital electrons. The study of hyperfine structure of ions can provide useful information on the nuclear structure and electronic properties of the ions. In our experiment Pr ions are produced using a surface ion source of Johnson type. Due to the high density of low lying thermally populated metastable levels in Pr II,

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many transitions can be investigated. The ions are accelerated to 20 kV and then mass separated by a 90° magnet. A collimated ion beam is obtained in the interaction region. In the interaction region ions velocity is tuned by applying an additional voltage and keeping the laser frequency constant (Doppler tuning) for the investigations of spectral lines in the region of 5762 Å to 5841 Å. A ring dye laser, pumped by an Argon ion laser, is used as the excitation source and we used dye Rhodamine 6G to obtain the desired laser wavelengths. Laser induced fluorescence is recorded by using a photomultiplier tube and a photon counter. Magnetic dipole constants A and electric quadrupole constants B of the involved levels have been determined using a fit program. Our results are in good agreement with published values.

POS-AMP-5 Experimental Confirmation of a Universally Valid Uncertainty Relation for Error and Disturbance in Spin-Measurements


J. Erhart*, S. Sponar*, G. Sulyok*, G. Badurek*, M. Ozawa†, and Y. Hasegawa*

*Atominstitut, Technische Universität Wien, Stadionallee 2, A-1020 Wien, Austria †Graduate School of Information Science, Nagoya University, Nagoya 464-8601, Japan

The uncertainty principle, which prohibits presice measurments of certain pairs of quantum mechanical observa bles, is one of the most remarkable consequences of quantum mechanics. It is well-known that Heisenberg, using the famous gamma-ray microscope thought-experiment [1], suggested a trade-off relation where the product of the measurement error of an observable and the disturbance on another observable caused by the measurement is not less than a bound set by the commutator between these two observables. Recently, Ozawa reconsidered this relation between the error and the disturbance by rigourous and general theoretical treatment of quantum measurements and derived the new relation, (A) (B)+ (A) (B) + (A) (B) ½ |< |[A,B]| >|

where are the error of the measurement A, the disturbance on the measurement B, and the standard deviations, respectively. In this talk, we report a neutron optical experiment that measures the error of a spin-component measurement as well as the disturbance caused on another spin-component measurement. This experiment confirms that the trade-off between the error and the disturbance completely obeys the new relation but violates the old one in a wide range of an experimental control parameter. Our results are the first evidence of the solution of a long-standing problem to describe the relation between the measurement accuracy and the disturbance caused by that measurement.

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References [1] Heisenberg, W. Über den anschaulichen Inhalt der quantentheoretischen Kinematik und Machanik, Z. Phys. 43, 172 (1927). [2] Ozawa, M. Universally valid reformulation of the Heisenberg uncertainty principle on noise and disturbance in measurements, Phys. Rev. A 67, 042105 (2003). [3] Ozawa, M. Uncertainty relations for noise and disturbance in generalized quantum measurements, Ann. Phys. 311, 350 (2004).

POS-AMP-6 Spin Ensembles on a Chip: Collective Effects in Cavity QED


K. Henschel 1*, J. Majer 2, J. Schmiedmayer2 and H. Ritsch1

1Institute for Theoretical Physics, Universität Innsbruck, Technikerstrasse 25, A 6020 Innsbruck, Austria E-mail: [email protected], TU Wien, Stadionallee 2, A 1020 Vienna, Austria

*Recipient of a DOC-fFORTE-fellowship of the Austrian Academy of Sciences

We study the dynamics of an ensemble of spins (two-level systems) coupled to a resonant microwave cavity mode. The ensemble can consist in a cloud of ultracold atoms or Nitrogen-Vacancy (NV) centers in a diamond. Despite the minute single spin coupling one obtains strong coupling between collective states and microwave photons enabling coherent transfer of an excitation between the long lived ensemble qubit state and the mode. Evidence of strong coupling can be obtained from the cavity transmission spectrum even at finite thermal photon number. In the case of NV centers additional line broadening due to remaining (not converted) Nitrogen in the crystal and NV-NV interactions have to be taken into account.

POS-AMP-7 Experimental Study on Optical Breakdown Induced by Polychromatic Laser Radiation

A. Kremsner, G. Reider, E. Schwarz, E. Wintner

Photonics Institute, Vienna University of Technology, Gusshausstrasse 25-29, 1040 Wien, Austria E-mail: [email protected] , Phone: +43 (1) 58801-38715 E-mail: [email protected] , Phone: +43 (1) 58801-38788 E-mail: [email protected] , Phone: +43 (1) 58801-38727 E-mail: [email protected] , Phone: +43 (1) 58801-38712

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We present experimental results concerning coherence effects in two color laser plasma generation in air at atmospheric pressure. Furthermore this experiment was also achieved at elevated pressures up to 10 bar. In order to obtain two-color radiation, second harmonic generation (SHG) can be employed. Therefore a commercial Q-switched 1064 nm Nd:YAG laser (Quantel Brilliant, pulse length 5 ns, maximum energy 250 mJ) was frequency-doubled via a KDP crystal. To obtain an overlap of the foci of the two wavelengths 1064 nm and 532 nm, a curved mirror with a HR coating for both wavelengths was used. These experiments have been conducted to optimize a laser ignition system for gas engines, which was developed by the “Laser Ignition Group” [1,2] at the “Institut für Photonik”. The outcome was a compact high peak power, passively Q-switched, longitudinally diode-pumped solid-state laser. One day this “laser spark plug” should replace conventional spark plugs because of the fact that conventional ignition has reached its limit in terms of efficiency and reduction of pollutant emissions.

References [1] H. Kopecek, E. Wintner, M. Lackner, F. Winter, and A. Hultqvist, Laser-

Stimulated Ignition in a Homogeneous Charge Compression Ignition Engine. SAE SP. 1819, 183 (2004).

[2] H. Kofler, J. Tauer, G. Tartar, K. Iskra, J. Klausner, G. Herdin, and E. Wintner, An Innovative solid-state laser for engine ignition. Laser Physics Letters. 4(4), 322 (2006).

POS-AMP-8 Implementation of a High-Power Frequency-Doubled Laser System for the Generation of an Optical Superlattice


L. Reichsöllner1, J. Danzl1, M. Mark1, E. Haller1, R. Hart1, A. Klinger1,O. Krieglsteiner1 and H.-C. Naegerl1

1Institut fuer Experimentalphysik und Zentrum fuer Quantenphysik, Universität Innsbruck, Technikerstraße 25/4, 6020 Innsbruck, Austria; E-mail of presenting author: [email protected]

Bose-Einstein condensates loaded into optical lattice potentials allow the realization of model Hamiltonians with exquisite control over the experimental parameters. Superimposing an optical lattice potential with a second lattice featuring exactly half the lattice spacing allows to generate a so called superlattice that features a tunable double-well configuration. We implement the fundamental lattice at a wavelength of 1064 nm and generate light at 532 nm for the short lattice by first power amplifying the 1064 nm light and subsequently frequency doubling it. For cesium atoms, the light for the fundamental

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lattice is red detuned with respect to the atomic transition, whereas the lattice at 532 nm is blue detuned and hence creates a repulsive potential. The superlattice will allow the investigation of novel quantum phases in optical lattices with complex occupation patterns and optimized formation of doubly occupied lattice sites for ultracold molecule production.

POS-AMP-9 Anomalous Intensity Distribution of Hyperfine Components of Praseodymium-I Lines


I. Siddiqui, G. Guthöhrlein and L. Windholz

Institut für Experimentalphysik, Techn. Univ. Graz, A-8010 Graz, Petersgasse 16 [email protected]

Experimental investigation of praseodymium-I line at wavelength 578.051 nm is reported. This investigation led to the observation of a laser induced fluorescence signal at 618.3 nm. The subsequently recorded hyperfine structure of the line showed an anomalous intensity distribution of its hyperfine components. The unusual intensity of hyperfine components was observed not only at 618.3 nm but also on other fluorescence lines i.e. 337.284 nm, 482.014 nm, 483.607 nm, 520.515 nm. Three groups of closely spaced hyperfine patterns are clearly seen and we concluded that three transitions are always excited. These closely spaced levels could disturb each other, explaining also the quite unusual intensity distribution of the hyperfine patterns. From the analysis of the wave numbers of the observed fluorescence lines we were able to determine the upper level of the excited transition at a wave number of 32486.80 cm-1, with J = 15/2 and even parity. Excitation with wavelength 618.3 nm confirmed our assumptions concerning energy and J of this upper level without doubt; its A-factor was 552.5 MHz. Thus we were able to locate three closely spaced levels with center-of-gravity distances 0.18 cm-1

and 0.68 cm-1 respectively as lower levels of the excited transitions. Up till now we have made 54 excitations from these narrow spaced levels to different known or unknown upper levels. In all these excitations an anomalous intensity distribution of hyperfine components is observed.

These levels are 15192.090 cm-1, J = 15/2, A = 730 MHz, odd parity 15191.906 cm-1, J = 13/2, A = 730 MHz, odd parity 15191.233 cm-1, J = 13/2, A = 666 MHz, odd parity

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POS-AMP-10 Experimental Investigation of Hyperfine Structure of Praseodymium-I Lines: Discovery of New Fine Structure Levels in Even and Odd Configurations

K. Shamim and l. Windholz

Institut für Experimentalphysik, Techn. Univ. Graz, A-8010 Graz, Petersgasse [email protected]

We report here the experimental investigation of the hyperfine structure of praseodymium-I lines using laser induced fluorescence spectroscopy in a hollow cathode discharge lamp. In this work 150 spectral lines were investigated which resulted in the discovery of 30 low lying new, up to now unknown levels, both in even and odd configurations. From the experimentally recorded data, using lock-in detection technique, magnetic hyperfine interaction constant ‘A’ and angular momentum ‘J’ were evaluated. With the help of the determined angular momentum ‘J’ and hyperfine interaction constant ‘A’, one of the involved levels is identified and the energy of the second new level is determined by the addition of the excitation wave number. The level found in this way explains fluorescence wavelengths and hyperfine structure of the fluorescence lines appearing in FT-Spectra. The newly discovered levels are further confirmed experimentally by excitations from other known lower levels.

POS-AMP-11 New Odd Parity Levels in Neutral Praseodymium


S. Tanweer I., and L. Windholz*

Institut für Experimentalphysik, Techn. Univ. Graz, A-8010 Graz, Petersgasse 16, Austria *Email: [email protected]

The spin-orbit interaction is the largest relativistic effect and is responsible for fine structure splitting in an atom. The hyperfine splitting of fine structure levels arise due to the interaction between electromagnetic multipole nuclear moments and the electromagnetic field produced at the nucleus by the electrons. In this investigation of the hyperfine structure of the praseodymium atom, presenting the discovery of thirteen newly found odd parity levels by investigation of spectral lines in the region 5640 Å to 6900 Å. In a hollow cathode discharge through the process of sputtering praseodymium atoms and ions are produced in ground and excited states which are then further excited to higher states by laser light. The excitation sources are operated with R6G or Kiton red ring-dye laser pumped by a solid state diode-pumped, frequency doubled Nd:Vanadate Nd:YVO4 Verdi V-18 laser system The

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hyperfine structure of these transitions has been recorded by using the method of laser induced fluorescence.

J-quantum numbers and magnetic dipole interaction constant A-values for upper and lower levels have been determined from the recorded hyperfine structure. The energies of the new up to now unknown levels have been obtained by using these constants, excitation and fluorescence wavelengths. The excitation wavelengths have been taken from FT Spectra [1]. Levels confirmed by a second laser excitation are given in the following table.

Excitation Wavelength Signal/Noise in FT Spectra Discovered Odd Levels Å J Energy/ cm 1

1 5757.311 7 15/2 32784.550 2 6057.921 17 9/2 28215.962 3 6161.912 3 5/2 27870.498 4 5784.751 19 9/2 23817.6245 5771.459 5 11/2 31650.0776 6789.737 3 5/2 26593.377 7 6596.887 4 17/2 27405.078 8 6207.232 21 9/2 22641.371 9 6142.813 3 17/2 32925.303 10 5664.825 3 17/2 35343.038 11 5726.241 6 17/2 33124.449 12 5740.394 7 11/2 30688.196 13 5911.494 7 5/2 31789.369 1. B. Gamper, Diploma Thesis, Technical University of Graz, 2007 (Unpublished)

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9.2 FAKT – Fachausschuss Kern- und Teilchenphysik

POS-FAKT-1 Design of a 1.42 GHz Spin-Flip Cavity for Antihydrogen Atoms


S. Federmann1,2, F. Caspers1, E. Mahner1, B. Juhasz2 and E. Widmann2

1CERN, Geneva, Switzerland 2Stefan Meyer Institute for Subatomic Physics, Vienna, Austria

The ground state hyperfine transition frequency of hydrogen is known to a very high precision and therefore the measurement of this transition frequency in antihydrogen is offering one of the most accurate tests of CPT symmetry. The ASACUSA collaboration at CERN will run an experiment designed to produce ground state antihydrogen atoms in a cusp trap. These antihydrogen atoms will pass with a low rate in the order of one per second through a spin-flip cavity where they get excited depending on their polarization by a 1.42 GHz magnetic field. Due to the small amount of antihydrogen atoms that will be available the requirement of good field homogeneity is imposed in order to obtain an interaction with as many antihydrogen atoms as possible. This leads to a requirement of an RF field deviation of less than ± 10% transverse to the beam direction over a beam aperture with 10 cm diameter. All design aspects of this new spin-flip cavity, including the required field homogeneity and vacuum aspects, are discussed.

References [1] B. Juhasz, E.Widmann, Hyp. Int. 193 (2009) 305 [2] N.F. Ramsey: Nobel Lecture (1989) [3] M. Shibata, A. Mohri, Y. Kanai, Y. Enomoto, Y. Yamazaki: Compact

cryogenic system with mechanical cryocoolers for antihydrogen synthesis, Review of Scientific Instruments 79, 015112 (2008)

[4] T. Kroyer: Design of a Spin-Flip Cavity for the Measurement of the Antihydrogen Hyperfine Structure, CERN-AB-Note, 2008

POS-FAKT-2 Readout Electronics for the Belle II Silicon Vertex Detector


C. Irmler1, T. Bergauer1, M. Friedl1, I. Gfall1, M. Valentan1

1 Institute of High Energy Physics, Nikolsdorfergasse 18, A-1050 Vienna, Austria [email protected]

A major upgrade of the KEK-B factory (Tsukuba, Japan), aiming at a peak luminosity of 8 x 10^35 / (cm^2s), which is 40 times the present value, is foreseen

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until 2013. Consequently an upgrade of the Belle detector and in particular its Silicon Vertex Detector (SVD) is required.

The new Belle II SVD will consist of four layers of double-sided silicon strip sensors at radii of 3.8, 8, 11.5 and 14 cm, completed by a double-layer pixel detector as the innermost sensing device. All DSSDs will be read out by the APV25 chip, which was originally developed for the CMS experiment. It has a peaking time of nominally 50ns, an integrated analog pipeline of 192 cells and has been proven to meet the requirements for Belle II in matters of occupancy and dead time. Since the KEK B-factory operates at relatively low energy, material budget inside the active volume has to be kept low to minimize multiple scattering.

We will present the concept of the readout electronics of the future Belle II SVD. Its front-end uses the APV25 readout chip arranged according to the Origami chip-on-sensor concept to ensure both low material budget and lowest possible amplifier noise. The VME back-end system not only digitizes the analog signals, but also provides on-board data processing and sparsification. It further allows determining exact hit timing with a precision of a few nanoseconds by taking six consecutive samples of the APV shaper output signal. Thanks to this feature, hits from background particles can be identified and discarded, which finally leads to a significant occupancy reduction. Even though the development of the readout electronics is still ongoing, we have successfully tested its building blocks on prototypes in several beam tests and the lab.

In 2009, the principal feasibility of the Origami concept [1] has been shown by building a prototype module using a 4" DSSD. Recently, new Belle II sensors (6") were delivered, and we are now assembling an Origami module for this full size sensor. Later this year, we want to build a full ladder of the outermost layer, as this will be the most complicated object and by demonstrating its producibility we thus prove the concept of the whole Belle II SVD. Starting from the assembly steps of the 2009 prototype, we will further elaborate and refine the procedure, aiming at a mechanical precision in the order of few 10um.

References [1] C. Irmler et al.,”Construction and Performance of a Double-Sided Silicon

Detector Module Using the Origami Concept”, CERN-2009-006, 211-215 (2009)

POS-FAKT-3 Quench Prevention of the LHC Quadrupole Magnets

C. Kurfürst1, B. Dehning2, C. W. Fabjan3, E. B. Holzer4,A. Nordt5 and M. Sapinski6

1865/1-C09, CERN, 1211 Geneva, Switzerland, [email protected], 2, 4, 5, 6865/1-C05, CERN, 1211 Geneva, Switzerland, 3Institute of High Energy Physics, Nikolsdorferg. 18, 1050 Vienna, Austria.

CERNs Large Hadron Collider (LHC) is a high energy proton accelerator and storage ring. Its design allows to reach unprecedented beam energies and beam

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intensities, resulting in a largely increased particle physics discovery potential. The combination of its high beam energy and intensity may lead to beam losses which can have a severe impact on the LHC equipment and damage sensitive elements. To protect those and to measure operational losses, a Beam Loss Monitoring (BLM) system has been installed all along the ring. The protection is achieved by extracting the beam from the ring in case thresholds imposed on measured radiation levels are exceeded. The thresholds are estimated through particle shower simulations. The simulated geometry and physic processes need to be precise in order to determine an optimum value, which therefore assures a high availability of the LHC for operation.This study is focused on the interconnection region between the main dipole and the main quadrupole magnet of the LHC. Six monitors are placed around the interconnection, three for each beam line. As proton impact location two loss patterns are assumed: one derived from halo particle tracking simulations and the other through analytic calculations relying on optical beam parameters. Particle shower simulations make the link between the amount of energy deposited in the superconducting coil and the signal measured in the ionisation chambers. The energy deposition in the coil results in its temperature increase. In case a critical temperature is exceeded, a transition from the superconducting state to the normal conducting one will occur. This transition is called a quench and is analysed for steady state and for fast transient losses. The fundamental parameters for the analysis are the critical power density and the enthalpy margin respectively. The combination of the detector signals allows the reconstruction of the loss pattern. Also the quench-protecting thresholds for two protection schemes have been evaluated. First LHC results are used to verify the simulations and considerations with measurements, so that conclusions about the simulation accuracy and observed loss patterns could be drawn. For transient losses the quench protecting threshold used as initial setting in the BLM system for the 2010 run is for the first ionisation chamber of 1520 μGy at injection energy and 178 μGy at 7 TeV beam energy. For steady state losses the used threshold for the first ionisation chamber is 4960 μGy/s at injection energy and 1876 μGy/s at collision energy.

POS-FAKT-4 The Federated Tier-2 Computing Center for LHC


D. Liko1,a, D. Kuhn2, N. Hörman1, G. Mair2 and W. Jais2

1Institute for High Energy Physics, Austrian Academy of Sciences, Vienna 2Institute for Astro and Particle Physics, University of Innsbruck [email protected]

The Worldwide LHC Computing Grid project (WLCG) [1] has established a global computing infrastructure for the analysis of LHC data [2]. It is based on several

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large grid projects, the EGEE project in Europe [3] and the Open Science Grid (OSG) in the US [4]. With the start of LHC a new international structure has been established in Europe, the European Grid Initiative (EGI) [5], to provide a sustainable support for the infrastructure in the coming years. In Austria, supported by the BMWF, the AustrianGrid project [6] has also established a federated Tier-2 centre for LHC with large computing clusters in Vienna and Innsbruck. It builds the basis for the LHC data analysis of the Austrian particle physics community. The Tier-2 is again supported by an Austrian National Grid Initiative (NGT_AT) that integrates into the European structure. With the start of the collider operation also the Austrian part of the grid has demonstrated its capabilities and data from the ATLAS and the CMS experiment are being analysed in Austria from the first day. As of today a number of other research areas, as biology, radio-biology and theoretical physics are also profiting from the available resources.

References [1] Worldwide LHC Computing Grid (WLCG), http://cern.ch/lcg,

Memorandum of Understanding, (CERN-C-RRB-2005-01/rev.), 2009. [2] The LCG Editorial Board, ”LHC Computing Grid Design Report”, LCG-TDR-

001 (CERN-LHCC-2005-024), 2005. [3] Enabeling Grids for E-SciencE (EGEE), http://www.eu-egee.org/,

FP7 Project INFSO-RI-222667 [4] Open Science Grid, http://www.opensciencegrid.org/ [5] European Grid Initiativehttp://www.egi.eu/,

EGI Bluprint, EU Deliverable D5.3, http://www.eu-egi.eu/blueprint.pd[6] Austrian Grid Project, http://www.austriangrid.at,

Austrian Grid is a project funded by the BMWF (Federal Ministry of Science and Research). Contract: GZ BMWF-10.220/0002-II/10/2007

POS-FAKT-5 Bound-State Stability in Bethe–Salpeter Equations with Instantaneous Confinement


W. Lucha

Institute for High Energy Physics, Austrian Academy of Sciences, Nikolsdorfergasse 18, A-1050 Vienna, Austria E-mail: [email protected]

Instantaneous Bethe–Salpeter equations with - supposedly - confining interaction kernels are expected to predict stable bound states with associated mass eigenvalues belonging to a part of the resulting total mass spectrum that is real, discrete and — preferably — bounded from below. Basically numerical studies,

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however, reveal that this requirement is not automatically satisfied. Hence, it has to be established in each individual case that for a chosen Lorentz structure of the kernel all desired spectral features are indeed achieved. Assuming the confining potentials to be of harmonic-oscillator form in configuration space greatly simplifies this kind of spectral analysis.

References [1] W. Lucha and F. F. Schöberl, “Instantaneous Bethe–Salpeter Equation with

Exact Propagators”, J. Phys. G: Nucl. Part. Phys. 31, 1133 (2005) [2] Li Z.-F., W. Lucha, and F. F. Schöberl, “Exact-Propagator Instantaneous

Bethe–Salpeter Equation for Quark–Antiquark Bound States”, Mod. Phys. Lett. A 21, 1657 (2006)

[3] Z.-F. Li, W. Lucha, and F. F. Schöberl, “Stability in the Instantaneous Bethe–Salpeter Formalism: Harmonic-Oscillator Reduced Salpeter Equation”, Phys. Rev. D 76, 125028 (2007)

[4] Z.-F. Li, W. Lucha, and F. F. Schöberl, “Stability in the Instantaneous Bethe–Salpeter Formalism: Reduced Exact-Propagator Bound-State Equation with Harmonic Interaction”, J. Phys. G: Nucl. Part. Phys. 35, 115002 (2008)

POS-FAKT-6 Quark–Hadron Duality and Effective Continuum Thresholds in Dispersive Sum Rules


W. Lucha1, D. Melikhov2,3,4 and S. Simula5

1Institute for High Energy Physics, Austrian Academy of Sciences, Nikolsdorfergasse 18, A-1050 Vienna, Austria E-mail: [email protected] for High Energy Physics, Austrian Academy of Sciences, Vienna, Austria 3Faculty of Physics, University of Vienna, Austria 4SINP, Moscow State University, Russia 5INFN, Sezione di Roma III, Roma, Italy

We consider the extraction of ground-state parameters within the framework of QCD sum rules, with emphasis on the crucial ingredient of this approach, viz., the effective continuum threshold, which governs the accuracy of the duality approximation. We propose a new algorithm to fix this quantity and probe both reliability and actual accuracy of sum-rule predictions at the example of quantum-mechanical potential models, which allow for comparison with the exact solutions. Our procedure yields a significant improvement of the accuracy of resulting ground-state parameters compared with standard sum-rule techniques used in all previous applications of dispersive sum rules in QCD. Moreover, the procedures of extracting ground-state decay constants in potential models and in QCD prove to be quantitatively very similar. Thus, the application of the proposed algorithm in QCD

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promises to result in a considerable increase of the accuracy of the extracted hadron parameters.

References [1] W. Lucha, D. Melikhov, and S. Simula, “Effective Continuum Threshold in

Dispersive Sum Rules”, Phys. Rev. D 79, 096011 (2009) [2] W. Lucha, D. Melikhov, and S. Simula, “Bound-State Parameters from

Dispersive Sum Rules for Vacuum-to-Vacuum Correlators“, J. Phys. G: Nucl. Part. Phys. 37, 035003 (2010)

[3] W. Lucha, D. Melikhov, H. Sazdjian, and S. Simula, “Effective Continuum Threshold for Vacuum-to-Bound-State Correlators”, Phys. Rev. D 80,114028 (2009)

[4] W. Lucha, D. Melikhov, and S. Simula, “Extraction of Ground-State Decay Constant from Dispersive Sum Rules: QCD vs. Potential Models“, Phys. Lett. B 687, 48 (2010)

[5] W. Lucha, D. Melikhov, and S. Simula, “Extraction of Bound-State Parameters from Dispersive Sum Rules“, arXiv:1003.1463 [hep-ph], Phys. Atom. Nucl. 73 (2010) (in print)

POS-FAKT-7 Recent Advances in AMS of 36Cl with a 3-MV-Tandem


M. Martschini1,*, O. Forstner1, R. Golser1, W. Kutschera1, S. Pavetich1,A. Priller1, P. Steier1, M. Suter2 and A. Wallner1

1 VERA Laboratory, Fakultät für Physik - Isotopenforschung, Universität Wien, Währingerstraße 17, A-1090 Wien, Austria; *[email protected] 2 Ion Beam Physics, Department of Physics, ETH Zürich, Schafmattstraße 20, CH-8093 Zürich, Switzerland

36Cl (t1/2 = 0.30 Ma) is widely used for exposure dating of carbonate rocks such as limestone and calcite. Accelerator mass spectrometry (AMS) with its high sensitivity allows to measure 36Cl at natural isotopic concentrations (36Cl/Cl ~ 10-13) but requires high particle energies for the separation from the stable isobar 36S. At VERA (Vienna Environmental Research Accelerator) we had performed the first 36Cl exposure dating measurement with a 3-MV tandem accelerator, operating our machine at 3.5 MV, using foil stripping and a split-anode ionization chamber [1]. We evaluated the performance of various detectors for 36Cl [2]. With the ionization chamber and a residual energy signal from a silicon strip detector, we now achieved an equally good 36S suppression at 3 MV terminal voltage compared to 3.5 MV in our previous measurements. To further increase the 36S suppression we investigated energy loss straggling in various counting gases and the effect of “energy focusing” [3] below the maximum of the Bragg curve. Comparison of experimental data with simulations and published data [3,4] yielded interesting

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insight into the physics underlying the detectors. Energy loss, energy straggling and angular scattering determine the 36S suppression. In addition, we improved ion source conditions, target backing materials and the cathode design with respect to sulfur output and cross contamination. These changes allow higher currents during measurement (35Cl current 5 �A) and also increased the reproducibility. We achieve an injector to detector efficiency for 36Clions of 8% (16% stripping yield for the 7+ charge state in the accelerator, 50% 36Cldetection efficiency), which compares favorable to other facilities. We will demonstrate that 36Cl measurements, which are competitive to larger tandems, are now possible.

References [1] P. Steier, O. Forstner, R. Golser, W. Kutschera, M. Martschini, S. Merchel,

T. Orlowski, A. Priller, C. Vockenhuber, A. Wallner, Nucl. Instr. Methods Phys. Res. B 268 (2010) 744

[2] T. Orlowski, O. Forstner, R. Golser, W. Kutschera, M. Martschini, S. Merchel, A. Priller, P. Steier, C. Vockenhuber, A. Wallner, Nucl. Instr. Methods Phys. Res. B 268 (2010) 847

[3] H. Schmidt-Böcking, H. Hornung, Z. Physik A286 (1978) 253 [4] L.C. Northcliffe, R.F. Schilling, Nucl. Data Tabl. A7 (1970) 233

POS-FAKT-8 Developments Towards Radiocarbon Dating of Ultra-Small DNA Samples


K. Mair, J. Liebl , P. Steier and W. Kutschera

Vienna Environmental Research Accelerator (VERA) Laboratory,Fakultät für Physik – Isotopenforschung, Universität Wien, Währingerstrasse 17, A-1090 Wien, Austria

Radiocarbon (14C) dating using Accelerator Mass Spectrometry (AMS) is a well established method. Standard methods of AMS typically require a sample size of about one milligram carbon, which, however, is not available in our recent efforts towards dating DNA from small human brain tissue samples using the 14C bomb peak [1]. We are presently developing methods to reliably measure samples in the range of ~10 g C. In decreasing the sample size, the main challenge is the control of the laboratory background which typically stays constant, and finally dominates the measurement result. In order to keep carbon contamination at the lowest possible level, an argon atmosphere – instead of air - was provided in sample handling, sample preparation, and ion source loading. Most of these tasks were performed in an argon glove box. Since we couldn’t find a significant difference in the carbon background for the ultra-small samples between sample preparation in laboratory air and argon atmosphere, we tested our argon-controlled set-up with mg-size samples of geological graphite (nominally zero 14C content), and found a radiocarbon age

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of 77 000 years BP. This is the lowest 14C background we have measured at VERA so far. It corresponds to a fraction modern carbon (F14C) value of (6.3 ± 1.4)x10-5. This is about one 14C half life "older" than samples processed in laboratory atmosphere. However, It was not possible to measure such a low value with ~10 μg graphitized carbon samples, because contamination from other sources seems to dominate the overall background. In a different investigation, we studied the mass of carbon contamination incorporated during different steps of sample preparation using small samples highly enriched in 13C. The amount of contamination with normal carbon (99% 12C) present in CO2 from sample combustion can be assessed by measuring 13CO2/12CO2 ratios using an RGA (residual gas analyzer). Additional contamination from the graphitization process was determined by measuring 13C/12C ratios with AMS. An overall amount of 0.12 to 0.15 g C contamination was found in this way [2].

References [1] Spalding, K. L., Bhardwaj, R. D., Buchholz, B. A., Druid, H., Frisen,

J., “Retrospective birth dating of cells in humans”, Cell 122, 133-143 (2005).

[2] Liebl, J., Avalos Ortiz, R., Golser, R., Handle, F., Kutschera, W., Steier, P., Wild, E. M., “Studies on the preparation of small 14C samples with an RGA and 13C enriched material”, accepted for publication in Radiocarbon.

POS-FAKT-9 Gem Detector Development for Hadron-Physics Experiments


P.Müllner1,a and J. Zmeskal1

1 Stefan Meyer Institut für subatomare Physik Boltzmanngasse 3, 1090 Wien a [email protected]

The next experiments in hadron-physics aim at studying rare processes with improved sensitivity (e.g. PANDA) [1]. The technical requirements for these experiments include fast detectors for charged particles with large acceptance and excellent tracking capabilities. With the GEM (Gas Electron Multiplier) technology it is possible to build detectors, which meet the demands for such experiments. The GEM technology bases on a thin polymide foil with a copper cladding on both sides [2]. A large number of microholes are chemically etched into this foil. By applying a voltage difference of several hundred volts, an electrical field of several kV/cm is produced inside the holes. Therefore the holes acts as a multiplication channel for electrons and as a trap for positive charged particles. A GEM detector is a gas detector with one or more GEM foils mounted between the cathode and anode.

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The SMI (Stefan Meyer Institute for subatomic physics) in Vienna build a triple GEM detector with an active area of 50x50 mm2, which was tested with PIXE (Proton Induced X-ray Emission) at the VERA (Vienna Environmental Research Accelerator). The location dependence of the intrinsic efficiency across the detection area was examined. Due to the collected experience from the results of these test, the SMI build now a new triple GEM detector prototype with a larger active area of 100x100 mm2 and improved readout electronics.

References [1] Schmitt, L., “The PANDA detector at FAIR”, Nuclear Instruments and

Methods in Physics Research A 581, 542-544 (2007) [2] Sauli, F., “GEM: A new concept for electron amplification in gas detectors”,

Nuclear Instruments and Methods in Physics Research A 386, 531-534 (1997)

POS-FAKT-10 AMS Measurement of the Reaction 35Cl(n, )36Cl and its Relevance to Astrophysics and Nuclear Technology


S. Pavetich1, T. Belgya2, M. Bichler3, I. Dillmann4, O. Forstner1, R. Golser1,F. Käppeler4, Z. Kis2, M. Martschini1, A. Priller1, P. Steier1, G. Steinhauser3,L. Szentmiklosi2 and A. Wallner1

1 VERA Laboratory, Faculty of Physics, University of Vienna, Währinger Str. 17, 1090 Vienna, Austria, [email protected] 2 Department of Nuclear Research, Institute of Isotopes, Hungarian Academy of Sciences, 1525 Budapest, Hungary 3 Atominstitut der Österreichischen Universitäten (ATI), Stadionallee 2, 1020 Vienna, Austria 4 Karlsruhe Institute of Technology (KIT), Postfach 3640, 76021 Karlsruhe, Germany

36Cl is a long-lived radionuclide (t1/2 = 301000 a), which is dominantly produced via the reaction 35Cl(n, )36Cl. The seed nuclei of this reaction, the stable 35Cl, acts as a neutron poison in the nucleosynthesis processes during later burning phases of stars. This makes the reaction important for astrophysical calculations, aiming to reproduce the abundances of elements. Due to the long half-life of 36Cl, the cross section and the production rate of the above reaction are also important for nuclear technology and nuclear waste management. The two main goals of this work are: (i) the production of an independent 36Cl/35Clstandard for accelerator mass spectrometry (AMS); and (ii) the determination of the Maxwellian averaged cross section (MACS) of 35Cl(n, )36Cl at 25 keV using AMS. Approaching the first goal, NaCl pellets were irradiated at the TRIGA Mark II reactor at the ATI in Vienna and at the Budapest research reactor. The neutron flux was monitored via the reference cross section of 197Au(n, )198Au (gold foils attached to

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and gold powder homogenously mixed into the pellets) and determined by activity measurements on the foils and the pellets. With this data we calculated a 36Cl/35Clratio for the irradiated samples. The AMS measurements on these samples were performed at VERA (Vienna Environmental Research Accelerator), relative to a standard from ETH Zurich. The comparison of the 36Cl/35Cl ratio calculated from the activity measurements and measured ratios by AMS shows a systematic discrepancy of 5%. To determine the neutron capture cross section of 35Cl, AMS measurements were performed on two samples, which were irradiated with neutrons of a Maxwell-Boltzmann energy distribution of 25 keV at the Forschungszentrum Karlsruhe. A preliminary mean value for the cross section is deduced by combining the AMS data and the neutron-fluence. The relevant cross section for nucleosynthesis in stars (MACS) will be calculated by weighting the mean value for the cross section with a Maxwell-Boltzmann energy distribution of 25 keV. The irradiation techniques and the measuring procedure by AMS will be discussed and our new results will be compared with previous measurements of neutron capture on 35Cl.

POS-FAKT-11 Temperature Dependent Nuclear Matter Approach


J. Haidvogl2, T. Srdinko1, D. Neudecker2 and H. Leeb2

1Inst. of Atomic and Subatomic Phys., TU Wien, Wiedner Hauptstr. 8,1040 Wien, [email protected], 2Inst. of Atomic and Subatomic Phys., TU Wien, Wiedner Hauptstr. 8,1040 Wien

The nuclear matter approach provides an effective interaction in the presence of a sea of nucleons. Especially it accounts for the Pauli principle which forbids scattering processes into the occupied states of the nucleonic see. It is well suited to describe the bulk properties of nuclei as well as optical potentials beyond 40 MeV incident energy. Difficulties in the description of nucleon-nucleus reactions beyond 70 MeV may indicate the importance of excited doorway states for reaction processes and therefore the optical potentials. In this contribution we consider the g-matrix approach for excited nuclear matter. The g-matrix is evaluated via the Bethe-Goldstone equation with an exact Pauli operator accounting for excitations with arbitrary occupation distributions. The features of the g-matrix with regard to changes in excitation are discussed.

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POS-FAKT-12 Study of Colour-Suppressed Bs Decays in Belle


M. Valentan, W. Mitaroff and C. Schwanda

Austrian Academy of Sciences – Institute of High Energy Physics Nikolsdorfer Gasse 18, A 1050 Vienna, Austria [email protected]

Mesons containing the heavy fifth quark b (called “bottom” or “beauty”) are of particular interest for investigations of the Standard Theory and beyond. Decays of these mesons are studied in the Belle detector at the “Beauty Factory” KEKB, an asymmetric e–e+ collider at the KEK Laboratory in Tsukuba, Japan. Tuning the collider to a center-of-mass energy of 10.86 GeV opens the resonant production of the (b anti-b) vector-meson 5S, decaying into Bs

(*) + anti-Bs(*) pairs of mesons

composed of a b and an s (“strange”) quark-antiquark. Object of this study are the exclusive decays Bs J/ , Bs J/ KS, and BsD0 KS which are colour-suppressed (in addition to being Cabibbo-suppressed). We present the experimental environment (KEKB accelerator and Belle detector), the data samples (more than 100 fb–1 have been collected in 2005 - 09), and techniques based on Monte Carlo simulation for extracting the signal events from the background.

FAKT-13 Operation of the CMS Tracker at the Large Hadron Collider


W. Adam, T. Bergauer, M. Dragicevic, M. Friedl, R. Frühwirth, St. Hänsel, M. Hoch, J. Hrubec, M. Krammer, M. Pernicka, E. Widl


The inner tracking detector of the Compact Myon Solenoid (CMS) Experiment at CERN is the largest semiconductor tracking device built so far. It consists of more than 25,000 individual silicon sensors with a total active area of almost 200 square meters. Its design, construction and commissioning was a huge effort of more than 50 institutes around the world and lasted almost seven years. The institute of High Energy Physics (HEPHY) of the Austrian Academy of Sciences contributed significantly to this project since its beginning by working on both the silicon strip and the pixel detectors. With the start of normal operation of the Large Hadron Collider (LHC), the CMS Tracker became operational as a scientific device and as part of the CMS

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experiment during data taking. Operation experience is gained continuously as the LHC delivers proton-proton collisions. In this presentation all critical systems of the tracker will be summarized and performance data will be presented. These numbers will show that both, the tracker and the whole experiment are working extremely well. First physics plots are already emerging, like measurements of the masses of different well-known particles. These measurements are helpful in calibrating the detector to be well prepared for the discovery of new physics as the LHC continues to deliver collision data.

FAKT-14 Kick response measurements during LHC injection tests and

early LHC beam commissioning


K. Fuchsberger1, M. Alabau Pons2, S. Fartoukh2, B. Goddard2, V. Kain2, M. Meddahi2, F. Schmidt2 and J. Wenninger2.

1CERN, Geneva, Switzerland, [email protected] 2 CERN, Geneva, Switzerland

The transfer lines from the SPS to the LHC, TI 2 and TI 8, with a total length of almost 6 km are the longest ones in the world. For that reason even small systematic optics errors are not negligible because they add up and result in an injection mismatch in the LHC. Next to other lattice measurement methods Kick-response measurements were the most important sources of information during the early phases of beam commissioning of these transfer lines and the LHC ring. This measurement technique was used to verify orbit-corrector and BPM gains as well as to sort out optics errors. Furthermore fits to off-momentum kick response turned out to be an appropriate method to establish a model for systematic errors of the transfer line magnets. This poster shortly describes the tools and methods developed for the analysis of the taken data and presents the most important results of the analysis.

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9.3 FKP – Festkörperphysik

POS-FKP-1 Investigation Of Precipitation Growth in Aluminium-Silver Alloys via in-situ SAXS


J. Akbarzadeh * and H. Peterlik *

* University of Vienna, Faculty of physics, Dynamics of Condensed Systems, Austria

Alloys have a big area of applications in engineering where they are mostly exposed to extreme conditions. Therefore, the knowledge about the influence of different parameters (e.g. high temperature exposition, external forces...) on their structure and later on their mechanical properties is of great importance for their production. In-situ small-angle x-ray scattering (SAXS) measurements offer the possibility to study the structural behaviour of materials under various conditions.In this work the temperature dependence of the precipitation growth was investigated in-situ via SAXS by two alloys: Al2at.%Ag and Al6at.%Ag. Changes in radii and the mean distance between the precipitations were, firstly, determined by "Guinier-fits" and afterwards by using the "Hard-Sphere-Model" [1]. The results of both calculation methods are depicted in graphics and are compared with each other. To realize the experiments, an x-ray transparent furnace was developed which could be mounted on a tensile machine. Due to this furnace, the investigation of the precipitations' shape modification in dependence of external load [2] and temperature was possible. It was found that there were no measurable changes in shape within a resolution limit of 1%.

References [1] J. S. Pedersen, Adv. Colloid Interface Sci. 70, 1997, 171-210 [2] Gupta et al., Acta Mater. 49 (2001) 53-63

POS-FKP-2 Microstructural and Electrical Analyses of Oxygen Diffusion into Iridium Metal Gates


A. Alexewicz1, C. Ostermaier1, G. Pozzovivo1, W. Schrenk1, M. Schmid2, L. Tóth3,B. Pecz3, J.-F. Carlin4, M. Gonschorek4, N. Grandjean4, J. Kuzmik1, 5, D. Pogany1,and G. Strasser1

1Institute of Solid State Electronics, Vienna University of Technology

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E-Mail: [email protected] of Applied Physics, Vienna University of Technology 3Research Institute for Technical Physics and Material Science, Budapest 4Institute of Quantum Electronics and Photonics, EPFL Lausanne 5Institute of Electrical Engineering, SAS Bratislava

Iridium is used as gate metal for GaN-based In0,17Al0,83N/AlN barrier High Electron Mobility Transistors (HEMTs) [1]. Before annealing, a high oxygen concentration confined at the Ir/InAlN interface is detected, but neither an aluminium nor an indium oxide interfacial layer has been formed. In this work we investigate the annealing-induced diffusion of the oxygen-rich interlayer and its electrical effects on the device. No stable iridium oxide forms – instead oxygen is able to diffuse out of the interlayer into the iridium gate metal, thus the interlayer is reduced. Above 700°C a homogeneous oxygen concentration is observed in the iridium layer, whereas at 500°C oxygen is distributed inhomogeneously. This behaviour is also verified electrically. The diffusion length of oxygen in evaporated iridium is only in the order of 1 nm for 2 minutes annealing at 500°C [2]. Therefore, oxygen cannot diffuse efficiently in dense iridium at that temperature, so that oxygen diffusion, enhanced by crystal defects and grain boundaries, is assumed. Annealing at 700°C increases the diffusion length to about 100 nm [2] and allows homogenous diffusion of oxygen into iridium, leading to the most complete removal of the oxygen interlayer, as seen from the C-V-measurements. Additionally, the analysis of the microstructure proves that the thickness of the InAlN/AlN barrier does not change after annealing and metal does not diffuse into the barrier. That confirms the already proven robustness of InAlN. The rapid thermal annealing was performed for 2 minutes at 400°C, 500°C and 700°C. Two samples with different gate metals (iridium and nickel) are analysed in order to investigate the dependence on the metal. High-Resolution TransmissionElectron Microscopy (HRTEM) gives detailed analysis of the microstructure at the different interfaces. Electron Energy Loss Spectroscopy (EELS) shows the two-dimensional element distribution in the samples. I-V- and C-V-measurements are used to determine the electrical properties.

References [1] C. Ostermaier, G. Pozzovivo, W. Schrenk, M. Schmid, L. Tóth, B. Pecz,

J.-F. Carlin, M. Gonschorek, N. Grandjean, J. Kuzmik, D. Pogany, and G. Strasser “Metal-related Gate Sinking due to Interfacial Oxygen Layer in Ir/InAlN High Electron Mobility Transistors”, Applied Physics Letters 96,263515 (2010)

[2] C. U. Pinnow, I. Kasko, N. Nagel, S. Poppa, T. Mikolajick, C. Dehm, W. Hösler, F. Bleyl, F. Jahnel, M. Seibt, U. Geyer, and K. Samwer “Influence of deposition conditions on Ir/IrO2 oxygen barrier effectiveness“, Journal of Applied Physics 91 (12), 9591 (2002).

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POS-FKP-3 Dynamics of Strongly Correlated Fermi Fluids


H. M. Böhm, R. Holler, E. Krotscheck, and M. Panholzer

Institut fütTheoretische Physik, Johannes Kepler Universität Linz, Austria E-mail: [email protected]

To date, understanding the quantum properties of fermionic many-particle systems forms a major challenge for both experimentalists as well as theorists. In the long wave-lengths regime, Landau’s concept of elementary excitations provides an elegant and powerful tool for describing the dynamic properties. It yields the well-known two types of modes: a collective one (“zero-sound” in 3 He, and “plasmon” in charged systems), plus a continuum of incoherent particle-hole excitations. At higher wave-vectors, the collective mode enters this band and is strongly damped. There seemed to be little room for further surprises in this field. However, recent experiments [1] performed on a monolayer of liquid 3He report the first observation of a roton-like minimum in a Fermi liquid. The collective mode reappears as a well defined excitation beyond the particle-hole band. We explain this re-emergence of the phonon (and predict a similar effect for the plasmon in charged systems) at the large wave vector edge (i.e. the low energy edge) of the particle-hole continuum from a manifestly microscopic theory. Our formalism is based on variationally optimizing the time-dependent fluctuations of the wave funcion. We derive energy dependent effective interactions accounting for two-pair excitiations and show how the form of the density-density response function must be changed from the paradigm of the RPA (random phase approximation) form. State-of-the-art results for the static ground state structure are used as an input.

This work was supported by the FWF under project nr. P21264-N20.

References [1] H. Godfrin, M. Meschke, H.J. Lauter, M. Meschke, H.M. Böhm,

E. Krotscheck, and M. Panholzer, J. Low Temp. Phys. 158, 147 (2010)

POS-FKP-4 3D Analysis of Nanocrystalline FeAl


C. Gammer1, C. Mangler1, H.-P. Karnthaler and C. Rentenberger3

1Physics of Nanostructured Materials, Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Wien, Austria [email protected]

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Nanocrystalline materials and nanostructures receive an increasing interest in materials science, since they often show unexpected physical properties. Their properties are closely linked to the size and 3D morphology of the nanostructures. Conventional transmission electron microscopy (TEM) analysis tools provide information on a projection of the nanostructures. Advanced analysis methods based on TEM can be used to determine the 3D morphology. In the present work a method based on TEM diffraction is developed that can be used to determine the size and morphology of the coherently scattering domains in 3D. In order to make bulk nanocrystalline materials several approaches have been used; one of them is based on their production by severe plastic deformation. Nanocrystalline intermetallic FeAl was made by high pressure torsion deformation of B2 ordered Fe-45at.%Al. The obtained bulk samples allow cutting out samples for TEM that can be directly linked to the shear direction and shear plane. Both, planar and cross sections of nanocrystalline FeAl were investigated to study the shape and morphology of the nanocrystals. In addition to the TEM images, electron diffraction patterns were recorded with a large range of different tilting angles. The morphology of the nanograins was analysed from the electron diffraction patterns by applying different tilting angles of the incident beam. A modified Williamson Hall plot was used to determine the coherently scattering domain size for each tilt angle. The analysis of the diffraction patterns was carried out with the software PASAD-tools (www.univie.ac.at/pasad). From the results it was possible to determine quantitatively the size and morphology of the nanograins in 3D. The results show that the nanograins have a ellipsoidal shape and are elongated in shear direction, which is in good agreement with TEM images. In addition to the possibility to analyse nanostructures in 3D, TEM provides conveniently the possibility to analyse locally selected areas of the sample in contrast to X-ray diffraction methods. Furthermore, due to the strong scattering factor, electron diffraction patterns can be recorded in seconds thus allowing to cover a large range of tilting angles in a short time.

POS-FKP-5 Numerical Study of Photonic Crystal Slab Based Quantum Well Infrared Photodetectors


R. Gansch1, S. Kalchmair1 and G. Strasser1

1Institute for Solid State Electronics, TU Vienna, 1040 Vienna, Austria

Photonic Crystals (PhC) provide properties like photonic bandgaps or negative refractive indices. By embedding a Quantum Well Infrared Photodetector (QWIP) into a PhC slab these photonic bandgaps can be used to manufacture spectral sensitive photonic detection devices in the mid infrared region. The PhC slabs can be analyzed numerically by several methods such as the 2D plain wave expansion method (PWEM) or 3D finite differences time domain (FDTD) simulation. However these methods are either inaccurate or very time consuming.

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The revised plain wave expansion method (RPWEM) combined with effective refractive indices to account for mode guiding in the slab offers results with great accuracy in a timely manner. Several devices were simulated employing this algorithm and results were compared to real manufactured devices.

References [1] Zabelin, V., “Numerical Investigations of Two-Dimensional Photonic Crystal

Optical Properties, Design and Analysis of Photonic Crystal Based Structures”, École Polytechnique Fédérale de Lausanne (2009)

POS-FKP-6 Magnetite Nanoparticles within a Semiconducting Matrix


P. Granitzer1, K. Rumpf1, M. Venkatesan2, A.G. Roca3, L. Cabrera3,M.P. Morales3, P. Poelt4 and M. Albu4

1 Institute of Physics, Karl Franzens University Graz, Universitaetsplatz 5, 8010 Graz, Austria, [email protected] 2 Institute of Physics, Trinity College Dublin, College Greeen, Dublin 2, Ireland 3 Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Inés de la Cruz 3, Cantoblanco, 28049 Madrid, Spain 4 Institute for Electron Microscopy, University of Technology Graz, Steyrergasse 17, 8010 Graz, Austria

Iron oxide nanoparticles are prepared by high temperature decomposition of iron organic precursor. The particles which are fabricated with an average size between 5 and 10 nm are coated with a surfactant in solution. Silicon is used as matrix for these monodisperse Fe3O4 particles to achieve a magnetic nanocomposite. For this purpose a silicon wafer is porosified by anodization in aqueous hydrofluoric acid solution. The iron oxide nanoparticles are infiltrated into the pores of the porous silicon resulting in a (dispersed nanoparticle/semiconductor)-composite with magnetic properties which are determined by the morphology of the silicon matrix as well as the distribution of the particles within the individual pores. The Fe3O4nanoparticles are superparamagnetic but the magnetic composite offers ferromagnetic properties below a certain blocking temperature due to dipolar coupling between the particles which can be influenced by the coating of the particles and the concentration of the particle solution. Furthermore the magnetic behaviour, especially the anisotropy between two magnetization directions (magnetic field parallel and perpendicular to the pores, respectively) can be modified by varying the morphology of the silicon matrix. The porous silicon/magnetite composite offers not only interesting magnetic properties with an adjustable transition temperature between superparamagnetic and ferromagnetic behaviour but it is also a promising candidate for biomedical applications due to the low toxicity of both materials.

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POS-FKP-7 Spin Ensembles on a Chip: Collective Effects in Cavity QED


K. Henschel 1*, J. Majer 2, J. Schmiedmayer2 and H. Ritsch1

1Institute for Theoretical Physics, Universität Innsbruck, Technikerstrasse 25, A 6020 Innsbruck, Austria E-mail: [email protected], TU Wien, Stadionallee 2, A 1020 Vienna, Austria

*Recipient of a DOC-fFORTE-fellowship of the Austrian Academy of Sciences

We study the dynamics of an ensemble of spins (two-level systems) coupled to a resonant microwave cavity mode. The ensemble can consist in a cloud of ultracold atoms or Nitrogen-Vacancy (NV) centers in a diamond. Despite the minute single spin coupling one obtains strong coupling between collective states and microwave photons enabling coherent transfer of an excitation between the long lived ensemble qubit state and the mode. Evidence of strong coupling can be obtained from the cavity transmission spectrum even at finite thermal photon number. In the case of NV centers additional line broadening due to remaining (not converted) Nitrogen in the crystal and NV-NV interactions have to be taken into account.

POS-FKP-8Structure and Luminescence Properties of Eu-doped Y2O3 Nano-Particles Prepared by Microwave Plasma Synthesis


A. Kautsch1, U. Brossmann1, H. Krenn2, F. Hofer3 and R. Würschum1

1 Institut für Materialphysik, TU Graz, 8010 Graz, Austria 2 Institut für Experimentalphysik, Karl-Franzens Universität, 8010 Graz, Austria 3 Institut für Elektronenmikroskopie, TU Graz, 8010 Graz, Austria

Rare-earth doped nano-crystalline oxides, e.g. Eu-alloyed Y2O3, offer attractive prospects as novel luminescent materials. A small particle size is known to alter the optical properties and is expected to contribute to an increased luminescence yield. In the present study, pure and 3-12 at.-% Eu-doped Y2O3 with a uniform, small initial grain size as a model system was for the first time prepared using low temperature microwave plasma synthesis. The specimens were structurally characterized by x-ray diffraction and transmission electron microscopy. The photoluminescence, both of dry powder samples and dispersions, was studied for excitation wavelengths in the UV and visible range.As synthesized, the samples are nano-amorphous and show only weak luminescence. The formation and growth of mixed Eu/Y oxide nano-crystals upon

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annealing and the concomitant increase of the luminescence yield is studied for different annealing temperatures and additions of Europium.

POS-FKP-9 Transporteigenschaften von Metall-Halbleiter separierten einwandigen Kohlenstoff-Nanoröhrchen


M. Sauer1, W. Lang1, S. Puchegger1, H. Peterlik1, M. Havlicek2, W. Jantsch2,M. Rümmeli3, H. Schalko4, K. Yanagi5, H. Kataura5, und H. Kuzmany1

1Universität Wien, Fakultät für Physik, A-1090 Wien, Strudlhofgasse 4, [email protected] Kepler Universität Linz, Institut für Halbleiter- und Festkörperphysik, A-4040 Linz 3Leibniz Institut für Festkörperphysik und Werkstoffforschung, D-01069 Dresden 4Technische Universität Wien, Institut für Sensor und Aktuatorsysteme, A-1040 Wien 5Tokyo Metropolitan University, Department of Physics, Tokyo, Japan

Einwandige Kohlenstoff-Nanoröhrchen sind bekannt für ihre besonderen mechanischen und elektronischen Eigenschaften. In den Letzten Jahren ist es gelungen metallisch leitende und halbleitende Röhrchen nahezu vollständig zu trennen. Dies ergab eine neue Ausgangssituation für Transportuntersuchungen und eine damit verbundene Herausforderung zur Untersuchung der Elektronen-Spinresonanz (ESR). In diesem Beitrag wird über Messungen der dc- und Hochfrequenzleitfähigkeit an Kohlenstoff-Nanoröhrchen als Funktion der Temperatur berichtet. Die Röhrchen wurden mit Hilfe eines nicht-magnetischen Katalysators bestehend aus PtRhRe durch Laserablation hergestellt um später optimale Voraussetzungen für Messungen der ESR zu gewährleisten. Anschließend wurden die metallischen und halbleitenden Strukturen mit Hilfe von Dichtegradient-Ultrazentrifugierung getrennt. Diese Vorgangsweise war analog zu jüngsten Untersuchungen an separierten Nanoröhrchen, die mit magnetischen Katalysatoren hergestellt waren [1]. Aus Messungen der Röntgenabsorption und der Abbildung im Raster-Elektronenmikroskop kann die effektive Probendicke ermittelt werden, die als Grundlage für die Bestimmung der elektrischen Leitfähigkeit dient. Da das separierte Material keine kompakte Struktur aufweist, sind die Ermittlungen der tatsächlichen Massendichten wichtig. Leitfähigkeitsmessungen erfolgten zwischen Raumtemperatur und 15 K. Die dc Leitfähigkeit der metallischen Röhrchen war bei RT mehr als 30-mal höher als die der halbleitenden Röhrchen. Bei tiefen Temperaturen war der Unterschied mehr als ein Faktor 700. Dieses Ergebnis zeigt, dass nicht, wie bisher angenommen, der Übergangswiderstand zwischen den Röhrchen ausschlaggebend für die elektrische Leitung ist, sondern sehr wohl die intrinsische Leitfähigkeit der Röhrchen. Aus den Werten der Leitfähigkeit ergibt sich für das Material der metallischen Röhrchen eine Skintiefe von 51 m bei

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Raumtemperatur und 28.5 m bei 15 K. Diese Werte sind wesentlich größer als die Dicke von 5-10 m der verwendeten Proben was seinerseits wieder entscheidend für die Analyse von ESR Spektren ist. Die Temperaturabhängigkeit Leitfähigkeit der halbleitenden Röhrchen war durch einen variable range hoping Prozess bestimmt.

Unterstützt durch den Fonds zur Förderung der Wissenschaftlichen Forschung in Österreich, Projekt P21333-N20 und P20550

Literatur [1] K. Yanagi et al.,“Transport Mechanisms in Metallic and Semiconducting

Single-Walled Carbon Nanotubes”, unveröffentlicht (2010).

POS-FKP-10 Pulse – Heating Technique Results of Platinum Alloys Compared with Modeling Results


S. Mehmood1, C. Cagran1, H. Sormann 2 and G. Pottlacher1

1Institute of Experimental Physics TU Graz, Petersgasse 16, A-8010 Graz, Austria, [email protected] for Theoretical Physics-Computational Physics, Petersgasse 16 II, A-8010 Graz, Austria

Platinum, a very precious metal, along with its alloys have many applications technically and also in ornaments such as in jewellery. Their thermophysical properties like density, heat capacity, thermal conductivity and surface tension play an important role in casting processes and are required as input data for casting simulation. The goal of this work is to investigate these properties and to simulate them through modeling. Platinum and three typical jewellery alloys namely Pt-5Co, Pt-5Ru and Pt-4Cu were investigated by an ohmic pulse heating technique [1]. This technique delivers thermophysical properties of electrically conducting materials deep into the liquid phase. Heating rates up to 108 K/s are achieved, and the liquid phase is achieved after about 30 μs. Within this short time the geometry of the sample will neither be destroyed through force of gravity, instabilities nor other effects, so that short-term measurements become possible on "standing” liquid columns. These measurements allow the calculation of specific heat capacity and the temperature dependencies of electrical resistivity, enthalpy, and density of these alloys in the solid and liquid phase. Thermal conductivity and thermal diffusivity as a function of temperature are estimated from resistivity data using the Wiedemann-Franz-law at the end of the solid phase and at the beginning of the liquid phase.Based on the temperature-dependent experimental data listed above, model calculations have been performed to achieve a deeper insight into the thermodynamical behavior of these materials both within the high-temperature solid and liquid regime. For such calculations, it is of special importance to choose model functions that are both physically relevant and numerically robust [2].

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References[1] Kaschnitz, E., Pottlacher, G. and Jäger, H., ’’ A New Microsecond Pulse-

Heating System to Investigate Thermophysical Properties of Solid and Liquid Metals ’’, International Journal of Thermophysics 13, 699-710 (1992)

[2] G. Grimvall, in „Scientific Modeling and Simulations“ , vol. 15, edited by S. Yip and T. Diaz de la Rubia (Springer-Verlag Berlin, 2009), pp. 5; 21; 41.

POS-FKP-11 Resonant Polarization Conversion and Extraordinary Transmission in Photonic Crystal Slabs Covered with Metal


R. Meisels1, O. Glushko1, S. Kalchmair2 and G. Strasser2

1Institute of Physics, University of Leoben, Leoben, Austria 2Center for Micro- and Nanostructures, TU Vienna, Vienna, Austria

In this work we show that optical transmission through subwavelength holes in a thin opaque metal layer can be substantially increased due to coupling of light to the eigenmodes of a 2D photonic crystal (PhC) located directly under the metal layer. The model system consists of a top gold layer and an underlying high-index dielectric substrate. A hexagonal lattice of cylindrical air holes is then "etched" through the gold layer and to some depth through the substrate. The parameters of the PhC are a=3 m, r=0.3a, h=4 m, where a is the lattice constant, r is the radius of the pores, and h is the depth of the pores. The system is excited by a plane-wave incident normal to the surface. We define y to be the propagation direction; the incident wave is polarized in z-direction (Ez 0, Hx 0). The results of our 3D finite-difference time-domain (FDTD) calculations for the near-field transmittance and reflectance are shown in Fig.1: We observe at least three pronounced dips in reflectance (and corresponding peaks in transmittance) which will be referred to as reflection dips 1, 2 and 3 corresponding to the notations in Fig. 1.

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It is important to note, that for the given parameters 67% of the surface is covered by the reflecting gold layer. However, the reflectance at =6.84 m (dip 3) is only 1%. The transmittance is 60% which means that the transmission efficiency, defined as transmitted power per unit area of the free surface (not covered by gold) is 180%. One can expect that each dip in reflection should correspond to an enhanced field below the gold layer. If we examine the distribution of the electric field within the PhC region we find that dips 1 and 3 correspond to a high amplitude of the Ey component (which is absent in the incident wave!) and the minimum of the dip 2 corresponds to a directly transmitted wave (high amplitude of the original Ez-component).For a quantitative characterization of the polarization conversion the intensities of the field components integrated over the volume of the PhC were

calculated. We have obtained |Ey|2/ |Ez|2=13.4 for the dip 3 and |Ey|2/ |Ez|2=13.8 for the dip 1. Another peculiarity of dips 1 and 3 is that the field has its maximal density just below the gold layer while for dip 2 the Ez-field is maximal in the middle of the pores. The yz cross sections of the absolute values of the corresponding electric field components are shown in the lower part of Fig. 1. By comparing reflectance spectra and field distributions obtained by the FDTD method with results of plane-wave method calculations we show that dips 1 and 3 appear due to the coupling of incident light to dipole eigenmodes of the PhC at the -point of the TM (E-field is parallel to the pores) band structure. This is confirmed

by the dependence of the positions of the dips on the radii of the pores and on the refractive index of the PhC. A physical model explaining the coupling to TM modes will be presented. Transmittance experiments are performed in GHz region by using a 6.6 mm thick ceramic plate with holes which is covered by a thin metal foil. The experiments confirm the existence of the transmission peak 3 showing, however, a lower value of the peak maximum.

This work was supported by the Austrian Nanoinitiative RPC PLATON.

Fig. 1. Top: reflectance (solid) and transmittance (dashed) spectra of the structure with 2D PhC with a= 3 m, r=0.9 m, and h=4 m. Bottom: the distribution of the absolute values of the field amplitudes of Ez (middle) and Ey (left and right) components (relative to the incident wave) at the wavelengths corresponding to three reflection dips. White corresponds to relative electric field amplitudes >4.

gold layer

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POS-FKP-12 Metallic Nanotubes in Porous Silicon


K. Rumpf1, P. Granitzer1, M. Venkatesan2, P. Poelt3 and M. Albu3

1 Institute of Physics, Karl Franzens University Graz, Universitaetsplatz 5, 8010 Graz, Austria, [email protected]

2 Institute of Physics, Trinity College Dublin, College Greeen, Dublin 2, Ireland 3 Institute for Electron Microscopy, University of Technology Graz, Steyrergasse 17, 8010 Graz, Austria

In the frame of this work Ni is electrochemically deposited within the pores of porous silicon. Typically the metal is precipitated as spherical, ellipsoidal or needle-like structures, exhibiting a diameter according to the pore-diameter of the matrix and an elongation between 60 nm up to a few micrometers, depending on the chosen process parameters. Additionally to these deposits small Ni-particles of a few nanometers in size (2 – 6 nm) covering the pore-walls can be deposited under certain conditions. Electrodeposition, which in general is influenced by charge transfer and mass transport of the reactants, allows various conditions. In choosing the parameters in such a way that accompanying effects as e.g. capacity effects are negligible, precipitates with spherical, ellipsoidal or needle-like shape can be fabricated. These Ni-structures are more or less randomly but evenly distributed within the pores. Furthermore small Ni-particles of a few nanometers in size can be precipitated, which cover the pore walls and form a metal tube. Investigating the Ni covering of the pore-walls more accurately a narrow distribution of these particles can be seen, which means that the particle-particle distance is below 10 nm and thus assures magnetic interactions. The small Ni particles are superparamagnetic but the dense distribution leads to dipolar interaction which is also shown in the magnetic behavior (e.g. coercivity, magnetic anisotropy). Thus the fabrication of ferromagnetic metal wires as well as of metal quasi-tubes within porous silicon can be achieved.

POS-FKP-13 Temperature and Size Dependent properties of NiO Nanoparticles


F. Shahzad1, P. Knoll1, K. Ettinger2, K. Nadeem1, I. Letofsky-Papst3, H. Krenn1,K. Pressl1, Á. Kukovecz4, G. Kozma4 and Z. Kónya4

1Institute of Physics, University of Graz, Universitätsplatz 5, 8010 Graz, Austria, E-mail: [email protected] of Earth Sciences, University of Graz, Universitätsplatz 2, 8010 Graz, Austria

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3Institute for Electron Microscopy, Technical University, Graz, Steyrerg. 17, 8010 Graz, Austria 4Department of Applied and Environmental Chemistry, University of Szeged, Hungary

Raman spectroscopy can also be used to study the properties of magnetic materials. A rather strong Raman signal is observed for antiferromagnetic spin ordering due to strong exchange mechanism in these materials. For example, NiO is an antiferromagnetic material with Néel temperature of 523K. There exists a 2-magnon peak, at about 1500cm-1, in the Raman spectra of this material. The behaviour of this 2-magnon peak is well understood for bulk NiO material. We have studied its behaviour in nanoparticles of this material. [1] NiO nanoparicles of different sizes (5-85nm) are prepared by Ball-milling and Sol-Gel methods. All the samples are well characterised by XRD, TEM, EDX and Rietveld refinement techniques [2,3]. Raman spectra are measured for all the samples with in temperature range of 25K to 300K to monitor antiferromagnetic spin ordering. These measurements have shown strong dependence of 2-magnon peak on temperature and particle size. No 2-magnon peak is observed for nanoparticles with sizes below 40nm, for larger size particles of 40nm and 85nm this peak strengthens with decrease of temperature and again vanishes at temperatures below 45K. [4] Magnetic measurements are performed for all NiO nanoparticle samples by SQUID magnetometer. Hysterisis curves are measured at different temperatures to observe ferromagnetic spin ordering. To see more accurate temperature dependence, Magnetisation vs. Temperature measurements are performed at constant external fields. These measurements have shown the evidence of paramagnetic and ferromagnetic spin ordering in NiO nanoparticles, which strengthen with decrease of particles size and increase of temperature.[5]

References [1] M. Pressl, M. Mayer, P. Knoll, S. Lo and U. Hohenster, J. of Raman Spec

27, 343-349 (1996) [2] Y. Wu, Y. He, T. Wu, T. Chen, W. Weng and H. Wan, Materials Letters 61,

3174-3178 (2007) [3] G. Kozma, Á. Kukovecz, Z. Kónya, J. of Molecular structure 834-836, 430-

434 (2007) [4] N. Mironova-Ulmane, A. Kuzmin, et al., J. of Physics: conference series 93,

012039 (2007) [5] S.D. Tiwari, K.P. Rajeev, Thin solid films 505, 113-117 (2005)

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POS-FKP-14 The Effect of Gating in Samples of Anti-Hall Bars within a Hall Bar


C. Uiberacker1, C. Stecher1 and J. Oswald1

1Montanuniversität Leoben, Inst. f. Physik;[email protected]

Due to the lack of realistic simulation tools for complicated quantum Hall samples there are lots of experiments that are not fully understood yet. Already some years ago R. G. Mani published an experiment using partial gating of a sample consisting of an anti-Hall bar within a Hall bar, where he recorded a shift of the Hall resistance transitions to lower magnetic fields, depending on the gating voltage. We use the Nonequilibrium Network Model (NNM) [2-4] to simulate this ”anti-Hall bar within a Hall bar” geometry and find the same qualitative behavior. Furthermore, by varying the carrier concentration, the bare gating voltage and the curvature of saddles, where tunneling leads to backscattering, and trying to fit the experimental curves, we can reproduce the true values of these quantities which are hard to measure directly.

References [1] R. G. Mani, “Dual Hall effects in inhomogeneous doubly connected

GaAs/AlGaAs heterostructure devices”, Appl. Phys. Lett. 70, 2879 (1997) [2] J. Oswald, “A new model for the transport regime of the integer quantum Hall

effect: The role of bulk transport in the edge channel picture”, Physica E 3,30 (1998).

[3] J. Oswald and M. Oswald, “Circuit type simulations of magneto-transport in the quantum Hall effect regime“, J. Phys.: Condens. Matter 18, R101 (2006).

[4] C. Uiberacker, C. Stecher, and J. Oswald, “Systematic study of nonideal contacts in integer quantum Hall systems”, Phys. Rev. B 80, 235331 (2009).

POS-FKP-15 Optical Conductivity of Graphene in the THz Frequency Range


A. Urich1, T. Mueller1, J. Darmo1 and K. Unterrainer1

1Vienna University of Technology, Institute of Photonics, 1040 Vienna, Austria

Since its discovery [1] in 2004, graphene - planar, hexagonal arrangements of carbon atoms - attracted much attention in different scientific fields. This is not only due to the fact, that truly two-dimensional crystalline systems like graphene were supposed not to exist, but mainly due to the unique electronic properties of this material.

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The crystal structure of graphene consists of two equivalent sublattices. Quantum-mechanical hopping of electrons between these sublattices leads to the formation of two energy bands that intersect at the points K and K'. Around these crossing points, the electron dispersion relation is linear and gapless in contrast to conventional metals and semiconductors. This fact is expected to result in strong interaction between graphene and terahertz radiation under certain conditions, and thus makes graphene a very interesting material for the terahertz spectral range. In this context, the optical conductivity is a key property of graphene. While the optical conductivity of graphene is constant for the visible spectral region, it is expected to show strong deviation from this behaviour in the THz frequency region [2]. This is due to the fact that interband transitions dominate in the visible range whereas, below the mid-infrared range, intraband transitions are dominant. We present an experimental approach to measure the optical conductivity of a graphene monolayer by means of THz time-domain-spectroscopy involving an on-chip coplanar waveguide structure for generation and detection of THz pulses.

References [1] Novoselov, K. et al., „Electric Field Effect in Atomically Thin Carbon Films“,

Science 306, 666 (2004) [1] Falkovsky, L. et al., „Optical far-infrared properties of a graphene monolayer

and multilayer“, Physical Review B 76, 153410 (2007)

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POS-FKP-16 Optimization of Coupling into Slow Light Modes of Planar Silicon Photonic Crystal Defect Waveguides in Aqueous Solutions


M. Wellenzohn1 and R. Hainberger1

1AIT Austrian Institute of Technology GmbH, Health and Environment Department, Nano Systems, Donau-City-Straße 1, 1220 Wien, E-mail: [email protected]

In planar 2D photonic crystal defect (PhC) waveguides the backscattering mechanism of light at each unit cell and omnidirectional reflection lead to the formation of slow light modes [1],[2]. We want to exploit these slow light modes for the development of a compact biophotonic sensor which is based on an integrated optical waveguide Mach Zehnder interferometer (MZI). This biosensor will be used for the detection of biomolecules such as proteins or DNA in aqueous solutions. The PhC sensor arm of the MZI is covered with a thin biosensitive layer to which only specific molecules can bind. This changes the phase velocity of the light, which can be sensitively measured by the MZI. The theoretic detection limits of such devices are as low as 0.1 pg/mm2 [3]. The slow light mechanism leads to a significant enhancement of the interaction between light and the sensitive layer by up to a factor of >100, which will allow reducing the sensing length of typically 1 cm in conventional waveguide devices to ~100μm. Achieving efficient coupling between a conventional wire waveguide mode and a slow light mode in a PhC defect waveguide represents a challenging task in the design of the sensor. A direct transition results in high losses. The major cause for these losses is the impedance missmatch between the conventional and PhC defect waveguide modes. For PhCs operated in air it has already been shown that a short intersection a PhC defect waveguide of a few microns supporting a faster mode can significantly enhance the coupling efficiency between the conventional and PhC defect waveguide [4]. By modifying the lattice periods and the hole diameters of this intersection PhC defect waveguide the group velocities can be adapted such that the coupling losses are reduced significatly [5],[6]. Since the targeted compact biophotonic sensor operates in aqueous solutions we optimized the coupling efficiency by means of extensive 2D Finite Difference Time Method (FDTD) simulations employing the effective index approach. In order to design a compact biophotonic sensor we used 3D Plane Wave Expansion Method (PWE) simulations for calculating the PhC band structure and the defect modes. While the majority of PhC devices are dedicated to telecom applications at 1550 nm wavelength using an air cladding, we designed our PhCs for an operation wavelength of 1310 nm, where the absorption in aqueous solutions is much lower than at 1550 nm. For PhCs operated in water the coupling issue becomes even more critical because the higher refractive index of water compared to air considerably reduces the PhC working range.

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We investigated PhC intersection areas with constant period lengths and adipatically reduced periods. Our simulation results explicitly indicate the increase of the coupling efficiency by the use of these concepts to reduce the impedance mismatch between the conventional and PhC defect waveguide modes. As a result, we obtained a new optimized PhC design for operation in aqueous solutions, which has a high potential to become a key component of compact biophotonic sensors.

References [1] J.B. Khugin, and R.S. Tucker,” Slow Light” , Science and Applications CRC

Press (2009) [2] T.F. Krauss, “Slow light in photonic crystal waveguides“, Journal of Physics

D: Applied Physics 40 , 2666-2670 (2007) [3] R. Narayanaswamy, and O. S. Wolfbeis, “Optical Sensors“, Springer (2004) [4] J.P. Hugonin, P. Lalanne, T.P. White, and T.F. Krauss, “Coupling into slow-

mode photonic crystal waveguides”, Optics Letters, Vol. 32, No. 18, 2638-2640 (2007)

[5] D. Bernier, E. Cassan, X. Le Roux, D. Marris-Morini, and L. Vivien,” Efficient band-edge light injection in two-dimensional planar photonic crystals using a gradual interface”, OE Letters Vol. 48(7), 070501-1 - 070501-3 (2009)

[6] B. Momeni, and A. Adibi, ”Adiabatic matching stage for coupling of light to extended Bloch modes of photonic crystals”, Applied Physics Letters 87,171104-1 -171104-3 (2005)

POS-FKP-17 Analytical and Numerical Study on Surface Emitting Ring Lasers


T. Zederbauer1, E. Mujagi 1, C. Schwarzer1, and G. Strasser1

1 Institute for Solid State Electronics, TU Vienna, 1040 Vienna, Austria

Grating coupled, surface emitting quantum cascade lasers (QCLs) featuring ring cavities provide unique features such as low beam divergence, tuneability and a circularly symmetric far field, which are highly desirable in many laser applications. To successfully design well suited waveguides for different purposes a profound knowledge of the waveguide resonant modes, the coupling constant, the polarization, and the far field pattern is crucial. In this work we present a numerical as well as an analytical approach to study and optimize the waveguide's properties. Far field patterns, polarization and mode distribution are acquired by performing 2D and 3D numerical simulations using COMSOL Multiphysics [1,2]. Analytical results are obtained by the use of a Floquet-Bloch approach to calculate mode distributions and coupling constants [3]. The numerical and analytical results are then compared and general rules for an efficient waveguide and grating design are considered.

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References [1] E. Mujagi , C. Deutsch, H. Detz, P. Klang, M. Nobile, A. M. Andrews, W.

Schrenk, K. Unterrainer, and G. Strasser, „Vertically emitting terahertz quantum cascade ring lasers“, Appl. Phys. Lett. 95, 011120 (2009).

[2] E. Mujagi , M. Nobile, H. Detz, W. Schrenk, J. Chen, C. Gmachl, and G. Strasser, “Ring cavity induced threshold reduction in single-mode surface emitting quantum cascade lasers”, Appl. Phys. Lett. 96, 031111 (2010).

[3] N. Finger, W. Schrenk, E. Gornik, “Analysis of TM-polarized DFB laser structures with metal surface gratings”, (2000) IEEE Journal of Quantum Electronics, 36 (7), pp. 780-786.

9.4 GEP – Geschichte der Physik

POS-GEP-1 Leopold Gottlieb Biwald’s Physica Generalisand the Tradition of its Sources


C. Faustmann

Recipient of a DOC-fellowship of the Austrian Academy of Sciences at the Institute of Classical Philology, Medieval- and Neolatin Studies, University of Vienna Dr. Karl Lueger-Ring 1, A-1010 Wien [email protected]

Published in several editions since 1767/1768, widely used all across Europe and officially designated for use at the universities and lyceums of the Habsburg monarchy in accordance with an imperial decree [1] Leopold Gottlieb Biwald’s Physica Generalis and Physica Particularis [2] held a place of particular significance among the physics textbooks of the 18th century [3]. As Biwald’s compendium is characterized by a special demand for being up-to-date, the author makes use of a wide range of sources presenting the contemporary state of scientific research. In particular Biwald goes back to 18th century textbooks which resemble his compendium regarding the layout and the presentation of information – such as works by Dalham, Hauser, Jaszlinszky, Lacaille, Mako, Mangold, Redlhamer, and Scherffer. Furthermore, Biwald refers to more subject-specific publications of current interest and in this context foremost to Boscovich’s publications. And as the Physica Generalis and Particularis represent a textbook propagating Newtonian physics above all, not only Newton’s Philosophiae Naturalis Principia Mathematicabut also several Newton-commentaries (especially publications by ’sGravesande, Keill, Maclaurin, and Pemberton) are to be considered mentionable sources of Biwald’s compendium.

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In this presentation the connection between the Physica Generalis and its sources is illustrated and particularly the relevance of the different types of sources for Biwald’s textbook as well as the author’s own achievements regarding the reception of relevant publications of 18th century physical technical literature are pointed out in order to illustrate the importance of Biwald’s compendium at its time.

References [1] Kons. Akt. Fasz. I/2, Reg. Nr. 205 [presently: Archive of the University of

Vienna CA 1.2.206]. [2] Biwald, L. G., “Physica Generalis”, Graecii 21769. – Biwald, L. G., “Physica

Particularis”, Graecii 21769. [3] Regarding positive estimations of Biwald’s compendium concerning this

matter cf.: Kunitsch, M., “Biographie des Herrn Leopold Gottlieb Biwald, der Weltweisheit und Gottesgelehrtheit Doctor, ehemaliges Mitglied des aufgelösten Jesuitenordens, ordentl. und öffentlicher Professor der Physik, Senior und Director der philosophischen Facultät, und gewesener Rector Magnificus an dem k. k. Lycäum zu Grätz”, Grätz 1808, 14f. – Valent, J., “Die Grazer Universität zur Zeit Josephs II. und die Lyzeumsjahre”, in: Bausteine zu einer Geschichte der Philosophie an der Universität Graz (Studien zur österreichischen Philosophie 33), ed. by Th. Binder et al., Amsterdam – New York 2001, 94. – Kernbauer, A., “Bildung und Wissenschaft im Wandel”, in: Steiermark. Wandel einer Landschaft im langen 18. Jahrhundert (Schriftenreihe der Österreichischen Gesellschaft zur Erforschung des 18. Jahrhunderts 12), ed. by H. Heppner & N. Reisinger, Wien – Köln – Weimar 2006, 381.

9.5 MBU – Medizinische Physik, Biophysik und Umweltphysik

POS-MBU-1 Brillouin Scattering in Ethanol-Water Mixtures


A. Asenbaum1, B. Kezic2, C. Pruner1,F. Sokolic2 and W. Emmerich1

1Experimental Physics, University of Salzburg, Salzburg, AUSTRIA; 2Department of Physics, University of Split, Split, CROATIA

We present Brillouin scattering measurements on ethanol-water mixtures at 293.15 K. The spectrometer was a 6-pass tandem Fabry-Perot interferometer with a finesse of about 80, FSR = 15.00 GHz. The scattering angle was 90°. Ultrasonic speed measurements at 3 MHz and index of refraction data at 514.5 nm are also reported. Of particular note is the sound dispersion between 0.1 and 0.6 mole

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fraction ethanol. The structural relaxation times derived from the experimental Brillouin spectra in the region around 0.2 mole fraction are in rough agreement with dielectric relaxation times.

POS-MBU-2 Brillouin Scattering in Lysozyme Solutions


A. Asenbaum1, C. Pruner1, E. Wilhelm1, A. Svanidze2,S. Lushnikov2 and A. Schulte3

1Experimental Physics, University of Salzburg, Salzburg, Austria; 2A. F. Ioffe Physical Technical Institute, St. Petersburg, Russia;

3University of Central Florida, Orlando, USA

We investigate the Brillouin spectrum of lysozyme solutions from 275 K to 335 K and compare to the spectrum of water. A six-pass tandem Fabry-Perot interferometer is used in both 90° and 180° geometries. Ultrasonic speed measurements at 3 MHz are also reported. The lysozyme concentrations are 200 mg/ml and 250 mg/ml, respectively. For the lysozyme solution, the observed higher values of the sound speed at GHz frequencies, as measured by Brillouin scattering, could indicate additional relaxation processes as compared to pure bulk water, where no sound dispersion between ultrasonic speed and hypersonic speed is observed.

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9.6 NESY – Physik an Neutronen und Synchrotronstrahlungsquellen

POS-NESY-1 Dynamical Effects in the Determination of Diffusion Coefficients from Scattering on isotopic Multilayers


F. Gröstlinger1, M. Leitner1, M. Rennhofer1 and B. Sepiol1

1Dynamics of Condensed Systems, Universität Wien, Strudlhofgasse 4, 1090 Wien, E-mail: [email protected]

The L10 phase of FePt exhibits a large magnetocrystalline uniaxial anisotropy which results in its high magnetic volume energy [1]. The magnetocrystalline and thermal stability of this phase makes it a suitable candidate for ultrahigh density recording. Thus detailed knowledge of the dynamic processes is essential for guaranteeing sufficient long-term stability of the magnetic domains. Nuclear Resonant Scattering (NRS) on isotopically varying but chemically homogeneous multilayers allows us to study diffusion coefficients down to 10-25

m2s-1 with high resolution of the diffusion length [2]. Up to now only the kinematical theory has been applied to evaluate the experimental data. However, this approach was criticized in a recent paper [3], which led to further investigation considering dynamical effects. We approached this by first calculating the change in the isotopic density by solving the diffusion equation with von Neumann boundary conditions. This density variation is discretized, fed into the standard software package CONUSS [4], to calculate the reflectivity from FePt layered systems, and fitted to our experimental data, as opposed to the kinematical theory which just compares the integrated intensities of the superstructure peaks. We conclude that for our samples these dynamical effects amount to a correction in the diffusion coefficient of only 20%, resulting in a value of (1.4±0.3)·10-24 m2s-1 at 673K. In materials with a higher density of resonant scattering centres and less absorption, though, the full dynamical theory for the determination of the diffusion coefficients has to be applied.

References [1] J.B. Staunton et al., J. Phys.: Condens. Matter 16, 5623-5631 (2004) [2] M. Rennhofer et al., Phys. Rev. B 74 (10), 104301 (2006) [3] M.A. Andreeva, N.G. Monina, S. Stankov, Moscow Univ. Bull. 63 (2),

132-136 (2008) [4] W. Sturhahn, E. Gerdau, Phys. Rev. B 49, 9285-9294 (1994)

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POS-NESY-2 Study of Novel Magnetic Materials Using the Usanspol Technique


E. Jericha1, G. Badurek1 and R. Grössinger2

1Atominstitut, Vienna University of Technology, Stadionallee 2, 1020 Wien, [email protected] für Festkörperphysik, Vienna University of Technology, Wiedner Hauptstraße 8-10, 1040 Wien

USANPOL is a novel ultra-small-angle scattering technique with polarised neutrons for investigation of magnetic materials. It represents a polarized neutron extension to traditional USANS which works with unpolarised neutrons. The high angular resolution of this technique relies and on the narrow reflection width of perfect crystal reflections and is employed in a double-crystal diffractometer. Corresponding to the μrad resolution of the set-up, micro-structures of the order of a few tenths of a micrometre up to a few tens of micrometres may be investigated. Neutron polarisation is achieved by insertion of birefringent magnetic prisms between the monochromator crystal and the sample. Rocking the analyser crystal produces a scattering pattern for both neutron spin states in a single measurement but well separated in reciprocal space. By this technique, we have recently studied various amorphous Galfenol soft-magnetic ribbons which were produced by spinning from melt at different manufacturing conditions. USANSPOL allows for a determination of domain sizes of the non-magnetised samples and a study of the growing of magnetically homogeneous regions with increasing externally applied magnetic field. The related measurement series is a beautiful demonstration of range, capabilities and structural size limits of the USANSPOL technique. The manufacturing process of the ribbons is clearly reflected in the magnetic micro-structure of the different specimens.

References [1] E. Jericha, G. Badurek, M. Trinker, “Ultra-small-angle scattering with

polarized neutrons”, Physica B 397, 88 (2007) [2] G. Badurek, E. Jericha, R. Grössinger, R. Sato-Turtelli, “Amorphous soft-

magnetic ribbons studied by ultra-small-angle polarized neutron scattering”,Journal of Physics: Conf. Ser. 211, 012027 (2010)

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POS-NESY-3 Holographically Prepared Diffraction Gratings For Neutron Interferometry


J. Klepp1, C. Pruner2, M. Fritzenwanker1, H. Rauch3,4, T. Nakamura5,Y. Tomita5 and M. Fally1

1Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna, Austria 2Department of Material Science and Physics, University of Salzburg, 5020 Salzburg, Austria, [email protected] 3Institut Laue Langevin, 6 rue Jules Horowitz, BP 165, F-38042 Grenoble Cedex 9, France 4Atominstitut, Vienna University of Technology, Stadionallee 2, 1020 Vienna, Austria 5University of Electrocommunications, Chofu-gaoka, Chofu, 1828585 Tokyo, Japan

We report on coherent elastic diffraction of thermal neutrons from gratings holographically prepared in nano-particle-dispersed polymers [1]. In contrast to a previously designed LLL-interferometer from polymethylmethacrylate (PMMA) based gratings [2] or holographic polymer dispersed liquid crystals (HPDLC) [3] these media offer a big variety of possibilities to optimize the diffraction properties for beam splitters and mirrors [4]. Thus nanoparticle dispersed polymers prove to be ideal materials for implementation as gratings in a neutron interferometer.

[1] Y. Tomita, N. Suzuki, K. Chikama, Opt. Lett. 30, 839 (2005) [2] C. Pruner, M. Fally, R. A. Rupp, R. P. May, J. Vollbrandt, Nucl. Instr. Meth.

A 560, 598 (2006) [3] M. Fally, I. Drevensek-Olenik, M. A. Ellabban, K.P. Pranzas, J. Vollbrandt,

Phys. Rev. Lett. 97, 167803 (2006) [4] M. Fally, M. Bichler, M. A. Ellabban, I. Drevenšek Olenik, C. Pruner, H.

Eckerlebe and K. P. Pranzas, J. Opt. A 11, 024019 (2009)

POS-NESY-4 Nuclear and Incommensurate Magnetic Structure of NaFeGe2O6Between 5K and 298K and New Data on Multiferroic NaFeSi2O6


G. J. Redhammer1, A. Senyshyn2,3, M. Meven2, G. Roth4, G. Tippelt1,C. Pietzonka5, W. Treutmann6 and G. Amthauer1

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1) Abteilung für Mineralgie, Fachbreich Materialforschung & Physik, Universität Salzburg,

Hellbrunnerstr. 34, A-5020 Salzburg, Austria

2) Forschungneutronenquelle Heinz Maier-Leibnitz (FRM II), Lichtenbergstrasse 1, D-85747

Garching, Germany.

3) Fachgebiet Strukturforschung, Materialwissenschaft, Technische Universität Darmstadt,

Petersenstr. 23, D-64278 Darmstadt, Germany

4) I Institut für Kristallographie, RWTH Aachen, Jägerstraße 17/19, D-52056 Aachen, Germany.

5) Fachbereich für Chemie, Philipps-University Marburg, Hans Meerweinstr., D-35032 Marburg/

Lahn, Germany

6) Institut für Mineralogie, Philipps-University Marburg, Hans Meerweinstr., D-35032 Marburg/ Lahn,

Germany

Pyroxene-type compounds are well known and studied in geo-science for decades. They are important constituents of the upper mantle and have a rich crystal chemistry, displaying several structural phase transitions as a function of temperature, pressure and chemical composition. However, they also posses interesting magnetic properties due to their low-dimensional structural characteristics with infinite chains of transition metal bearing M1-octahedra; the geometry of M1-octahedra and the interplay of magnetic moments within and between these chains is determining the magnetic spin structure. Among the members of the pyroxenes, one can find compounds with spin-gaps, pure ferro- and pure antiferromagnets and even multiferroics. In the last few years, we have studied in great detail the low temperature magnetic properties of the pyroxenes, among them CaM(Si,Ge)2O6 with M = Fe2+, Ni2+, Co2+ and Mn2+, LiFe3+(Si,Ge)2O6LiCrGe2O6, FeGeO3, MnGeO3 or CoGeO3 [1 and references therein). In the present contribution we present results on the synthetic germanate-pyroxene NaFeGe2O6and compare the results with the analogue silicate, also known as the fancy mineral aegirine. The compound NaFeGe2O6 was grown synthetically as polycrystalline powder and as large single-crystals suitable for X-ray and neutron diffraction experiments to clarify the low temperature evolution of secondary structural parameters and to determine the low temperature magnetic spins structure. NaFeGe2O6 is isotypic to the clinopyroxene-type compound aegirine and adopts the typical HT-C2/cclinopyroxene structure down to 2.5 K. The Na-bearing M2 polyhedra were identified to show the largest volume expansion between 2.5 K and room temperature, while the GeO4 tetrahedra behave as stiff units and tend to shrink with increasing temperature. Magnetic susceptibility measurements show a broad maximum around 33 K, which marks the onset of low-dimensional magnetic ordering. Below 12 K NaFeGe2O6 transforms to an incommensurately modulated magnetic spin state, with k = [0.323, 1.0, 0.080] and a helical order of spins within the M1-chains of FeO6 octahedra. This is determined by neutron diffraction experiments on a single-crystal. Comparison of NaFeGe2O6 with NaFeSi2O6 is given and it is shown that the magnetic ordering in the latter compound, aegirine, also is complex and best is described by two different spin states, a commensurate one with C2'/c' symmetry and an incommensurate one, best being described by a spin density wave, oriented within the (1 0 1) plane.

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References [1] Redhammer GJ, Roth G, Treutmann W, Hoelzel M, Paulus W, André G,

Pietzonka C, Amthauer G (2009a) The magnetic structure of clinopyroxene-type LiFeGe2O6 and revised data on multiferroic LiFeSi2O6. J Solid State Chem. (doi: 10.1016/j.jssc.2009.06.013)

NESY-5 Optimisation of spatial neutron spin resonance


G. Badurek, Ch. Gösselsberger and E. Jericha

Atominstitut, Vienna University of Technology, Stadionallee 2, 1020 Vienna, Austria, [email protected]

Drabkin's famous concept of spatial neutron spin resonance [1] is expanded to a new type of neutron spin resonator. In combination with a pair of high performance polarising devices a Drabkin-type resonator could be used not only as monochromator with variable output wavelength at fixed take-off angle but also as ultra-fast electronic chopper with arbitrary repetition rate and, even more important, adaptive time-of flight resolution. In this case extremely flexible instruments for neutron scattering experiments become feasible which will allow an almost instantaneous variation of key machine parameters like the mean wavelength and spectral width of the incident beam, and the overall time and energy resolution by purely electronic means without any mechanical modification. The original Drabkin-type spin resonator produces a spatially alternating magnetic field by means of a meander-shaped conducting foil with fixed geometry. But the neutron-chopping ability of our proposed new type of resonator requires an assembly of individual, separately switchable modules [2]. However, using just a sequence of separate current-sheets leads to a loss of field homogeneity due to edge effects. Thus a well-balanced assembly, yielding sufficiently homogeneous magnetic fields and satisfying simultaneously the requirements of fast electronic switching, has to yet be developed. In order to find the optimal resonator configuration we present a detailed analysis of various possible arrangements. At first we intend to exploit the outstanding performance of such a type of neutron spin resonator within the PERC project [3], which searches for new physics beyond the Standard Model of particle physics at hitherto unrivalled level of sensitivity. There the benefit of such a device will be an increased count rate because it allows a replacement of the velocity selector and the chopper from the originally planned “standard” set-up.

REFERENCES

[1] G.M. Drabkin, V.A. Trunov, V.V. Runov, “Static magnetic field analysis of a polarised neutron spectrum”, Sov. Phys. JETP 27, 194-196 (1968)

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[2] G. Badurek, E. Jericha, “Upon the versatility of spatial neutron magnetic spin resonance”, Physica B 335, 215-218 (2003)

[3] http://www.physi.uni-heidelberg.de/Forschung/ANP/PERC/collaboration.php

9.7 OGD – Oberflächen, Grenzflächen und Dünne Schichten

POS-OGD-1 CuN Structures on Cu(110)


M. Hohage, M. Denk, and P. Zeppenfeld

Institut für Experimentalphysik, Johannes Kepler Universität Linz, A-4040 Linz, Austria [email protected]

Chemisorption of atomic nitrogen on Cu(110) leads, at a saturation coverage of 2/3, to the formation of a well ordered Cu(110)-(2x3)N reconstruction upon annealing at 650 K [1], [2].An in-depth study concerning the formation of the nitrogen induced reconstruction has been performed to address open questions regarding the exact structure of the surface at the atomic scale.In case the annealing temperature is below 550 K, a precursory Cu-N phase which consists of elongated molecule-like structures, termed “CuN compounds”, has been found on the surface by Scanning Tunneling Microscopy (STM). The CuN compounds are characterised by their high mobility on the surface and have been found to be stable up to at least 550 K. The compounds are expected to play a crucial role in the formation of the final (2x3)N phase, as the Cu coverage of the surface layer is increased to 4/3 as compared to the pristine Cu(110) surface. A model structure for the CuN compounds has been derived from the analysis of the STM images. The CuN compounds may consist of Cu4N subunits, which appear as bright dots in the STM images.

References [1] D. Heskett, A. Baddorf and E. W. Plummer, Surf. Sci., 195, p. 94 (1988) [2] A. P. Baddorf and D. M. Zehner, Surf. Sci., 238, p. 255 (1990)

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POS-OGD-2 AFM based Morphological and Electrical Characterization of Hot Wall Epitaxy Grown 6P/SiO2


M. Kratzer1, S. Klima1, I. Beinik1, Q. Shen1, A. Lugstein2 and C. Teichert1

1Institute of Physics, University of Leoben, Franz Josef Straße 18, A8700 Leoben, Austria 2Institut für Festkörperelektronik, TU Wien, Floragasse 7/1, A1040 Wien, Austria

In the present study, the growth of thin para-hexaphenyl (6P) films on silicon oxide has been investigated. The 6P layers were fabricated by hot wall epitaxy (HWE) at substrate temperatures ranging from 273K to 423 K. As substrates Si(100) wafers covered with native or thermally grown oxide were used. The film morphology was determined by conventional tapping mode atomic force microscopy (TM-AFM). While the films grown at high temperature consisted of large domains formed by upright standing molecules the low temperature grown films were essentially amorphous and contained a number of additional structures. The influence of temperature treatment on the morphology of the low temperature grown 6P films was additionally investigated. For electrical characterization, 6P layers were deposited onto SiO2 patterned with Au electrodes. The so formed field effect transistor (FET) structures were investigated by Conductive Atomic Force Microscopy (C-AFM) and Kelvin Probe Force Microscopy (KPFM). The results were correlated with the film morphology. Support by the Austrian Science Fund FWF is acknowledged.

Corresponding author: [email protected]

POS-OGD-3 Role of Surface Defects on Hydrogen Outgassing of Stainless Steel


M. Leisch1, A. Juan2

1Institute of Solid State Physics, Graz University of Technology, 8010 Graz, Austria, E-mail: [email protected] de Fisica, Univ. National del Sur, 8000 Bahia Blanca, Argentina

Stainless steel (SS) is one of the most commonly used constructional materials for vacuum chambers and components. Special applications like accelerator, storage ring facilities or advanced semiconductor device processing make need for extreme high vacuum (XHV). In the XHV regime a reduction of the outgassing rates of the

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materials used in the construction of the vacuum system is essential. Beside surface treatment to reduce the surface roughness high temperature vacuum firing became an alternate method and widely accepted practice of reducing the amount of hydrogen dissolved in SS. For the description of the outgassing rate basically two models common as diffusion limited model (DLM) and recombination limited model (RLM) have been discussed. Surface states which may influence the outgassing kinetics significantly are not considered in the DLM. It is well established that the rate of recombination depends strongly on the atomic structure of the surface and is e.g. generally higher on stepped surfaces than on flat close packed planes. In order to gain atomic level information on the real morphology of a surface after common bake-out and vacuum firing SS samples were imaged in the atomic force microscope (AFM) and the scanning tunnelling microscope (STM). The main experimental work has been carried out on a combined STM – atom probe field ion microscope (AP-FIM) apparatus [1]. A unique feature of the particular combined instrument is that it allows a fully-predictive preparation of STM probe tips in situ by FIM which is important for a reliable imaging of complex surfaces.The surface after vacuum firing shows significant reconstruction with formation of large flat terraces which can be assigned to (111) planes. These terraces are bounded by bunched steps and facets corresponding in orientation almost to (110) planes and (100) planes. The deep grooved grain boundaries, facets and bunched atomic steps represent very active sites for adsorption and recombination of hydrogen. A close up view on the large (111) terraces by STM show that there are a lot of vacancies too. Theoretical studies and simulations on the interaction of hydrogen with lattice imperfections provide a new insight in hydrogen outgassing. The energy calculations [2] using the ASED method (Atom superposition and Electron Delocalization) result in lower energy levels in tetrahedral sites in Fe vacancies. It supports the picture that surface and subsurface defects form traps with different energetic levels. They may control the recombinative desorption process and give explanation for the observed hydrogen outgassing behaviour of stainless steel.

References [1] Stupnik A Frank P Leisch M Ultramicroscopy 109 (2009) 563 [2] Rey Saravia D Juan A Brizuela G Simonetti S I J Hydrogen Energy 34 (2009) 8302

POS-OGD-4 Para-Sexiphenyl on Silicon Dioxide: Growth and Annealing


S. Lorbek1, Q. Shen1 and C. Teichert11Institute of Physics, University of Leoben, A-8700 Leoben, Franz Josef Strasse 18, [email protected]

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Although progress has been made in the recent years in the understanding of fundamental growth processes in organic molecular beam epitaxy, the underlying details are still to be explored [1]. Especially, understanding of the island nucleation on the substrate during the deposition of oligomere molecules is crucial for the design of growth routes that will avoid an undesired formation of 3D structures. This is important for the fabrication of electronic devices based on such organic materials with well defined physical characteristics. Here, sub-monolayers of the rod-like molecule para-sexiphenyl (p6P) have been deposited onto the isotropic surface of SiO2 under ultra-high vacuum, resulting in islands of almost upright standing molecules. Right after the deposition, a short annealing step was performed with different time durations and at different temperatures [2, 3]. As an effect due to this annealing the grown islands began to shrink until their structure vanished completely. To investigate this process the islands size, distribution, fractal dimension [4] and molecule orientation has been studied by in-situ and ex-situ atomic force microscopy in intermittent and contact mode [5].

References [1] G. Hlawacek, et al., “Characterization of Step-Edge Barriers in Organic Thin-

Film Growth”, Science 321 (2008) 108 [2] J. Yang, et al., “Ultrathin-Film Growth para-Sexiphenyl (I): Submonolayer

Thin-Film Growth as a Function of the Substrate Temperature”, Journal of Physical Chemistry B 112 (2008) 7816

[3] J. Yang, et al., “Ultrathin-Film Growth para-Sexiphenyl (II): Formation of Large-Size Domain and Continuous Thin Film”, Journal of Physical Chemistry B 112 (2008) 7821

[4] F. Meyer zu Heringdorf, et al., “Growth dynamics of pentacene thin films”, Nature 412 (2001) 517

[5] S.N. Magonov, et al., “Phase imaging and stiffness in tapping-mode atomic force microscopy”, Surface Science 375 (1997) L385

POS-OGD-5 Surface Morphology Investigations of Cellulose Films


O. Miškovi 1,3, F. J. Schmied1,3, M. Djak2,3, R. Schennach2,3 and C. Teichert1,3

1Institute of Physics, University of Leoben, Franz Josef Strasse 18, 8700 Leoben 2Institute of Solid State Physics, Graz University of Technology, Petersgasse 16/2, 8010 Graz 3CD-Laboratory for Surface Chemical and Physical Fundamentals of Paper Strength, Graz University of Technology, Petersgasse 16/2, 8010 Graz Corresponding author: [email protected]

Pulp fibers are natural fibers that consist of cellulose fibrils, embedded in a hemicellulose and lignin matrix. The nano- and microstructure of these fibers - as

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well as its influence on the fiber-fiber bond strength - is not yet completely understood. There are several bonding models proposed [1] but the major mechanism is still unclear. Like other biological samples, pulp fibers are not uniform and therefore show a wide variety of different features like length, shape, diameter etc.. Therefore, the properties of cellulose films as a function of film thickness have been analyzed. Based on atomic force microscopy (AFM) investigations, a comprehensive roughness analysis was performed, calculating root-mean-square roughness ,lateral-correlation-length and the Hurst parameter .First results are revealing changes in the surface morphology, depending on the film thickness. Additionally, hemicellulose was spin-coated on the cellulose film and its influence was investigated.

Supported by Lenzing AG and the Christian Doppler Research Society, Vienna, Austria.

References [1] T. Lindström et al., 13th Fundamental Research Symposium, Cambridge,

(2005) 457

POS-OGD-6 A Comparative Study of Charge Transport and Meyer-Neldel Rule In Fullerene Devices


M. Ullah1, A. Pivrikas2, C. Simbrunner1, G. J. Matt1, N. S. Sariciftci2 and H.Sitter1

E-mail: [email protected] of Semiconductor and Solid State Physics, JKU Linz, Austria. 2Linz Institute of Organic solar cells, LIOS, JKU Linz, Austria.

We measure the charge carrier mobility using two techniques, in the bulk of fullerene films using Charge Extraction by Linearly Increasing Voltage (CELIV) technique [1] and at the interface of insulators using Organic Field Effect Transistors (OFET) [2]. We observed that the electron mobility is at least two orders of magnitude higher than hole transport in the C60 films prepared by thermal evaporation. Electric field, carrier concentration and temperature dependences of the electron mobility was measured using both methods. More than one order of magnitude higher charge carrier mobility values are measured in OFET configuration due to high charge carrier concentrations at the quasi 2D transport near the dielectric interface. We comparatively present the carrier concentration and electric field dependence of the charge carrier mobility in both devices. Meyer-Neldel Rule (MNR) is observed in both fullerene devices [3,4]. Meyer-Neldel energy, EMN = 35 meV, which is interpreted as disorder parameter [5], is the same in both device geometries, which suggest that the level of disorder is similar in the bulk of fullerene films and at the interface with insulators

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References [1] A. Pivrikas, Mujeeb Ullah, Th. B. Singh, C. Simbruner, G. Matt, H. Sitter2and

N. S. Sariciftci , Organic Elecrtronics submitted. [2] Mujeeb Ullah, D. M. Taylor, R. Schwödiauer, H. Sitter, S. Bauer,

N. S. Sariciftci and Th. B. Singh, Journal of Applied Physics, 106, 114505 (2009).

[3] Mujeeb Ullah, T.B. Singh, H. Sitter, N.S. Sariciftci, Applied Physics A, Materials Science & Processing 97 (2009), 521.

[4] Mujeeb Ullah, I. I. Fishchuk, A. Kadashchuk, P. Stadler, A. Pivrikas, C. Simbrunner, V. N. Poroshin, N. S. Sariciftci, and H. Sitter, Appl. Phys. Lett. 96,213306 (2010).

[5] I. I. Fishchuk, A. K. Kadashchuk, J. Genoe, Mujeeb Ullah, H. Sitter, Th. B. Singh, N. S. Sariciftci, and H. Bässler, Phys. Rev. B 81, 045202 (2010).

POS-OGD-7 High Mobility, Low Voltage Operating C60 Based n-type Organic Field Effect Transistors


M. Ullah1, M. Irimia-Vladu2, M. Reisinger2, Y. Kanbur3, G. Schwabegger1,R.Schwödiauer2, S. Bauer2, N. S. Sariciftci4 and H.Sitter1

E-mail: [email protected] of Semiconductor and Solid State Physics, JKU Linz, Austria. 2Institute of Soft Matter Physics, SOMAP, JKU Linz, Austria. 3Department of Polymer Science and Technology, Middle East Technical University, Balgat, Ankara, 06531, Turkey 4Linz Institute of Organic Solar Cells, LIOS, JKU Linz, Austria.

We have reported the state-of-the-art C60 based bottom gate-top contact transistors by engineering different organic materials (BCB, Polyethylene and Adenine) / metal-oxide (AlOx) bilayer as gate dielectric. The engineering of metal-oxide and organic material passivation bilayer combines the advantages of having a high dielectric metal oxide and a thin passivation layer of polymer or small molecule capped on AlOx layer. The passivation layer helps both smoothing the dielectric surface and suppressing the leakage current while providing good interface properties with the semiconductor layers. This results in OFETs that operate at voltages less than 500 mV. The AlOx layers are readily processible from solution and cured at low temperature, instead of traditionally sputtering or high temperature processing, thus this process is suitable for low-cost organic field effect transistors (OFETs) manufacture. The output characteristics of the OFETs show well saturation behavior while the transfer characteristic display an on/off ratio in excess of 103.The OFET devices have a high field effect mobility which ranges from 2 - 5 cm2/V s for different passivation layers, with low threshold voltages ~ 0.02 V - 0.05 V.

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References [1] Mujeeb Ullah, D. M. Taylor, R. Schwödiauer, H. Sitter, S. Bauer, N. S.

Sariciftci and Th. B. Singh, Journal of Applied Physics, 106, 114505 (2009). [2] P. Stadler, A. M. Track, M. Ullah, H. Sitter, G. J. Matt, G. Koller, T. B. Singh,

H. Neugebauer, N. S. Sariciftci, M. G. Ramsey, Organic Electronic 11 (2010), 207-211

POS-OGD-8 Organic Heterolayers: an in-situ GIXRD Study of Sexiphenyl and Pentacene


M. Oehzelt1, G. Koller2, T.U. Schülli3, T. Haber4, R. Resel4, M.G. Ramsey2

and P. Zeppenfeld1

1Institute of Experimental Physics, JKU Linz, Altenbergerstr. 69, 4040 Linz, Austria [email protected] 2Institute of Physics, KFU Graz, Universitätsplatz 5, 8010 Graz, Austria 3CEA-Grenoble, SP2M/NRS, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France 4 Institute of Solid State Physics, TU-Graz, Petersgasse 12, 8010 Graz, Austria

Organic heterostructures of pentacene (5A) and para-sexiphenyl (6P) are studied in-situ with X-ray diffraction methods. The single crystal copper (110) surface was used as substrate to align the first molecular film uniaxially.[1] The deposited pentacene molecules exhibit a high degree of order and serve as a template for the second molecular layer. The sequence of layers was chosen in such a way that the molecule with the lower sublimation temperature (5A) was overgrown by a molecular layer with higher sublimation temperature (6P). XRD measurements of the completed heterostructure reveal that the molecules orient within a few degrees parallel to the direction of copper [1-10]. [2-3] The molecules in the second layer are also crystalline and the long molecular axes of the 6P molecules follow closely the directions of the underlying pentacene molecules. As the packing and orientation of the crystalline layers is very similar it was possible to detect diffraction peaks of the whole heterostructure on the same ccd-image simultaneously. Heating this heterostructure to the sublimation temperature of pentacene, which is lower due to its lower molecular weight compared to 6P, evaporates the pentacene molecules through the 6P layer leaving only the 6P layer while keeping the original orientation of the 6P molecules. A 2D-detector allows to study this evaporation process in-situ and in real-time and can monitor the changes in both organic layers simultaneously. The overgrown 5A layer is evaporated first due to its lower sublimation temperature. During this process, the 6P rocking width increases, and fully recovers after the 5A layer is gone. Moreover, the orientation of the 6P crystallites is not altered upon to the evaporation process. It was thus possible to transfer a 6P(20-3) oriented layer

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[5] onto Cu(110) whereas 6P deposited directly on the clean copper (110) substrate crystallizes (62-9) oriented. [1]

References [1] M. Koini, et. al. in prep. [2] M. Oehzelt, G. Koller, J. Ivanco, S. Berkebile, T. Haber, R. Resel, F.P.

Netzer, M.G. Ramsey, Advanced Material 18, 2466 (2006)[3] G. Koller, S. Berkebile, J.R. Krenn, F.P. Netzer, M. Oehzelt, T. Haber, R.

Resel, M.G. Ramsey, Nano Letters 6, 1207 (2006). [4] M. Koini, T. Haber, O. Werzer, S. Berkebile, G. Koller, M. Oehzelt, M.G.

Ramsey, R. Resel, Thin Solid Films 517, 483 (2008). [5] M. Oehzelt, L. Grill, S. Berkebile, G. Koller, F.P. Netzer, M.G. Ramsey,

Chem. Phys. Chem. 8, 1707 (2007).

POS-OGD-9 Characterization of Individual ZnO Nanorods by Atomic Force Microscopy


L. Wang1, I. Beinik1, M. Kratzer1, A. Djuriši 2 and C. Teichert1

1Institute of Physics, University of Leoben, Franz Josef Straße 18, A 8700 Leoben, Austria 2Department of Physics, University of Hong Kong, PR China Corresponding author: [email protected]

ZnO has come into focus of researchers due to its versatile physical and chemical properties. Its wide band gap (3.37eV), large exciton binding energy (60meV at room temperature), piezoelectricity and surface chemistry make ZnO an interesting candidate for novel electronic devices. In this study, the morphology and electrical properties of ZnO nanorods (NRs), grown by hydrothermal synthesis and thermal evaporation on conductive substrates were investigated by atomic force microscopy (AFM). Their resulting shape and dimensions were determined by AFM in tapping mode. In order to get an insight in the electrical properties, two-dimensional current maps at different bias voltages were measured by conductive atomic force microscopy (C-AFM). Additional C-AFM was utilized to determine the current-to-voltage (IV) characteristics of the top facets of individual upright standing NRs. The C-AFM data was correlated with the topography.

Support by the FWF project Nr. P19636 is acknowledged.

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POS-OGD-10 Reaction of Methanol on ZnO modified Pd(111)


F. Weber1, M. Piffl1 and R. Schennach1

1Institute of Solid State Physics, Graz University of Technology, Graz, Austria, [email protected]

The reaction of methanol with water to form carbon dioxide and hydrogen is very important for example for direct methanol fuel cells. As the electrodes of fuel cells are very sensitive to CO poisoning a high selectivity for carbon dioxide is of the utmost importance. In industry this reaction has been performed using a Cu/ZnO catalyst [1]. While the selectivity and the activity of the catalyst is quite good, it looses both over time due to sintering of the copper particles. Therefore people changed to a Pd/ZnO catalyst. While Pd is known to be selective for carbon monoxide formation, it was found that the Pd/ZnO catalyst shows even higher selectivity towards carbon dioxide than the Cu/ZnO catalyst [2]. This surprising result was attributed to the formation of a Pd/Zn alloy under reaction conditions, possible due to partial reduction of the ZnO. Here we will present results on the reaction of methanol on a Pd(111) surface covered with ZnO islands as an invers model catalyst. The ZnO islands are prepared by reactive Zn evaporation under an oxygen atmosphere. The structure of the resulting ZnO islands has been investigated using scanning tunnelling microscopy. The methanol reaction is studied using thermal desorption spectroscopy and infra red reflection absorption spectroscopy.

The results of the methanol reaction will be presented and discussed with respect to the available results in the literature.

References [1] Iwasa, N., Yamamoto, O., Akazawa, T., Ohyama, S., Takezawa, M.,

“Dehydrogenation of methanol to methyl formate over palladium/zinc oxide catalysts”, J. Chem. Soc. Chem. Commun. 18 , 132 (1991)

[2] Iwasa, N., Kudo, S., Takahashi, H., Masuda, S., Takezawa, N., “Highlyselective supported Pd catalysts for steam reforming of methanol”,Catal. Lett. 19, 211 (1993)

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POS-OGD-11 Time-Dependent Heat Conduction Problems Solved by an Integral-Equation Approach


E. R. Oberaigner, M. Leindl and T. Antretter

Institute of Mechanics, University of Leoben, Franz-Josef-Strasse 18, A 8700 Leoben, Austria E-Mail: [email protected]

A classical task of mathematical physics is the formulation and solution of a time-dependent thermoelastic problem. In this work we develop an algorithm for solving the time-dependent heat conduction equation

0, iitp kTTcin an analytical, exact fashion for a two-component domain. By the Green's function approach [1,2] the formal solution of the problem is obtained. As an intermediate result an integral-equation for the temperature history at the domain interface is formulated which can be solved analytically. This method is applied to a classical engineering problem, i.e. to a special case of a Stefan-Problem [6]. The Green's function approach in conjunction with the integral-equation method is very useful in cases were strong discontinuities or jumps occur. The initial conditions and the system parameters of the investigated problem give rise to two jumps in the temperature field. Purely numerical solutions are obtained by using the FEM (finite element method) [3] and the FDM (finite difference method) [5] and compared with the analytical approach. At the domain boundary the analytical solution and the FEM-solution are in good agreement, but the FDM results show a signicant smearing effect.

References [1] Barton, G., “Elements of Green's Functions and Propagation”, Oxford

Science Pub.,Oxford, 1989 [2] Butkovskiy, A.G., “Green’s Functions and Transfer Functions

Handbook”, Ellis Horwood Ltd., Chichester, 1982 [3] Kikuchi, N., ”Finite Element Methods in Mechanics”, Cambridge University

Press, Cambridge, 1986 [4] Lui, I-S., “Continuum Mechanics”, Springer-Verlag, Berlin, Heidelberg, New

York, 2002 [5] Ozisik, M. N., “Finite Difference Methods in Heat Transfer”, CRC-Press,

Boca Raton, Florida, USA, 1994 [6] Rubinstein, L.I., “The Stefan Problem”, Trans. Math. Mono. 27, Amer. Mat.

Soc., Providence, Rhode Island, USA, 1971

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POS-OGD-12 Influence of Surface-Functionalized Nanoparticles on The Structural Properties of Polymer Nanocomposites


S. Pabisch1, B. Feichtenschlager2, G. Kickelbick3 and H. Peterlik1

1University of Vienna, Faculty of Physics, Boltzmanngasse 5, A 1090 Vienna, Austria, E-mail: [email protected] University of Technology, Institute of Materials Chemistry, Getreidemarkt 9, A 1060 Vienna, Austria 3Saarland University, Inorganic Solid State Chemistry, Dudweiler, Am Markt Zeile 3, D 66125 Saarbrücken, Germany

Inorganic-organic polymer nanocomposites are a promising materials class for many future applications e. g. the replacement of heavy weight materials by novel light systems with similar or even better properties. [1] Furthermore, such novel materials even comprise additional functionalities in fields like optics or electronics. [2] The chemical parameters of the inorganic-organic building block surface-functionalization have an effect on the macroscopic properties of the materials and, therefore, a detailed study of this influence gives novel insights into the importance of surface-functionalization. Two types of nanoparticles, SiO2 and ZrO2, are synthesized in two different particle sizes, one in the lower nanometer length scale (5-15 nm in diameter) and one in the upper nanometer length scale (30-60 nm in diameter). The compounds prepared and surface-functionalized are incorporated in three different polymer matrices: epoxide resin, polyacrylate and polystyrene. Structural characterization of the resulting nanocomposites is performed by small angle X-ray scattering (SAXS): From the SAXS intensity, information on the size of nanoparticles and their agglomeration behaviour is obtained. This work focuses on the agglomeration behaviour of nanoparticles with different surface-functionalization and different size embedded in three different polymer matrices.

References [1] H. Presting, U. König, Mater. Sci. Eng., C 2003, C23, 737 [2] M. Tanihara, T. Miyazaki, S.-i. Ogata, C. Ohtsuki, in Handbook of Organic-

Inorganic Hybrid Materials and Nanocomposites, Vol. 2 (Ed.: H. S. Nalwa), American Scientific Publishers, Stevenson Ranch, 2003, pp. 265

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INDEX of PRESENTING AUTHORS

Abele, H., 71, 72 Adaktylos, T., 46, 65 Adam, G., 61,159, 178 Ahmed, G., 58, 83 Akbarzadeh, J., 180 Akhtar, N., 160, 161 Alam, K., 123,128 Alexewicz, A., 180 Alkofer, R., 55, 64 Amenitsch, H., 88, 93, 96 Andrews, A.M., 91, 108, 109 Anjum, N., 160, 161 Asenbaum, A., 197, 198 Badurek, G., 162, 200, 203 Bauer, G., P., S. 98, 107, 113, 141, 156, 209 Beinik, I., 135, 153, 205, 211 Benedikt, M., 56, 70, 88, 92 Bergauer, T., 54, 61, 62, 84, 178 Berkebile, S., 22, 28, 33, 137, 138 Bertel, E., 134, 143 Besser, B., 116, 117 Blank, M., 55, 67, 68 Böhm, H., 182 Bramwell, S., 15, 19 Brehm, M., 91, 113 Brossmann, U., 185 Buchsbaum, A., 89, 99 Chen, G., 89, 101 Chen, X. 153 Chen, Z.-S., 36 Cristofolini, P., 42, 50 Cvetkovi , B., 56, 69 Denk, M., 134, 144, 204

216

Detz, H., 91, 108, 109 Dragicevic, M., 61, 62, 178 Dungel, W., 21, 23, 27 Ellmeier, M., 42, 48 Enzinger, E., 35, 40 Erko, M., 88, 94 Ernst, W., 47, 49, 50, 155 Ertl, S., 68 Fabjan, C., 56, 71, 169 Faustmann, C., 196 Federmann, S., 168 Ferlaino, F., 28, 31 Fleming, A.J., 22, 133, 137, 138 Friedl, M., 61, 62, 84, 168, 178 Friedreich, S., 57, 78, 79 Frisch, W., 58, 81 Fröschl, R., 58, 82 Fuchsberger, K., 54, 59, 179 Gall, J., 134, 146 Gammer, C., 182 Gansch, R., 183 Geist, D., 90, 103 Gfall, I., 58, 84, 168 Giessen, H., 14, 18 Gragnaniello, L., 135, 152 Granitzer, P., 184, 190 Greiner, M., 7, 8 Grimm, R., 14, 17, 27, 31 Gröstlinger, F., 95, 199 Gruber, T., 42, 49 Grumiller, D., 68 Haas, G., 28, 30, 121 Hartmann, O., 57, 72 Haynl, I., 135, 151

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Henschel, K., 163, 185 Hiesmayr, B., 41, 44, 46, 52, 55, 65, 66 Hipp, F., 46, 65 Hitzenberger, R., 34 Hörmann, N., 58, 81 Hofmann, W., 125, 129, 132 Hohage, M., 144, 146, 204 Huber, M., 41, 44, 46, 52, 55, 65, 66 Huemer, E., 54, 62 Hussain, M., 123, 129 Irmler, C., 84, 168 Jenke, T., 57, 72 Jussel, P., 55, 63 Južni , S., 116, 119 Kautsch, A., 185 Kienberger, R., 14, 16 Kiesenhofer, W., 55, 64 Kirchsteiger, C., 7, 8 Kiymaz, F., 35, 38 Knünz, V., 54, 62 Krammer, M., 61, 62, 178 Krassnigg, A., 55, 67, 68 Kratzer, M., 153, 205, 211 Kremsner, A., 51, 163 Krenn, H., 89, 97, 100, 185, 190 Kreuzer, W., 35, 36, 37 Kuhn, D., 63, 170 Kumagai, O., 14, 19 Kurfürst, C., 169 Kuzmany, H., 186 Lackner, F., 42, 50 Lederer, C., 57, 75 Lechner, R., 89, 91, 98, 114 Leitner, M., 88, 95, 199

218

Lettner, H., 123, 125, 131 Libisch, F., 29, 90, 104 Liko, D., 81, 170 Lorbek, S., 206 Lucha, H., 171, 172 Madl, P., 124, 132 Mair, K., 57, 76, 175 Mandl, B., 91, 110 Markum, H., 116, 117 Marmiroli, B., 88, 93, 96 Martschini, M., 57, 77, 80, 173, 176 Massiczek, O., 57, 78, 79 Mayrhofer-Reinhartsgruber, M., 135, 155

Mehmood, S., 187 Meisels, R., 188 Mihocic, M., 35, 39 Miškovi , O. 207 Mitaroff, W., 178 Mittermayr, F., 54, 59 Moldaschl, T., 91, 111 Moser, A., 90, 105, 147 Müller, T., 25, 28, 32, 111 Müllner, P., 58, 87, 175 Nadeem, K., 89, 97, 100, 190 Neudecker, D., 58, 82, 177 Oberaigner, E.R., 213 Oehzelt, M., 148, 210 Pabisch, S., 214 Pagana-Hammer, B., 28, 30, 121 Paris, O., 21, 24, 94, 114 Parz, W., 21, 25, 111 Pavetich, S., 58, 77, 80, 173, 176 Penjweini, R., 123, 126 Pfingstner, J., 58, 85

219

Pfleiderer, C., 88, 92 Pichler, F., 116, 119 Pichler, T., 89, 102 Piffl, M., 212 Pillmayr, N., 7 Primetzhofer, D., 29, 90, 107, 135, 141, 156 Pruner, C., 197, 198, 201 Puschnig, P., 21, 22, 147, 148 Radic, S., 46, 65 Ramsey, M., 22, 137, 138, 210 Ratschek, M., 42, 47 Rauch, H., 201 Redhammer, G.J., 201 Reichl, C., 134, 150 Reichsöllner, L., 164 Resel, R., 105, 134, 147, 148, 210 Rieckh, G., 35, 36, 37 Ritsch, E., 54, 63 Rumpf, K., 184, 190 Rund, S., 134, 141 Sauer, M., 186 Saghafi, S., 126 Sachslehner, F., 22, 26 Schauberger, G., 123, 124, 130 Schimpf, H., 46, 65 Schmid, M., 99, 134, 140 Schmid, P., 121, 122 Schmidt, W.F.O., 123, 124 Schöfbeck, R., 15, 56, 60 Schreiner, S., 116, 118 Schuster, P.-M., 22, 26, 116, 120 Schwarz, C., 7, 10 Schwarz, E., 42, 51, 163 Shamim, K., 166

220

Siddiqui, I.A., 165 Simbrunner, C., 134, 148, 208 Spengler, Ch., 42, 46, 52, 65 Srdinko, T., 82, 177 Strasser, G., 25, 108, 109, 111, 180, 183, 188, 195 Suchorski, Y., 134, 145 Sun, L., 133, 138, 144, 146 Tanweer, I.S., 166 Tautz, S., 133, 136 Teichert, C. 147, 153, 154, 205, 206, 207, 211 Thim, H., 116, 119 Thomas, M., 7, 12 Thomay, C., 54, 60 Uiberacker, C., 41, 45, 90, 108, 192 Ullah, M., 135, 157, 208, 209 Urich, A., 192 Ursin, R., 14, 17, 27 Valentan, M., 84, 168, 178 Wagner, M., 133, 137 Wagner, T., 133, 139 Waldner, H.M., 46, 65 Waltenberger, W., 56, 70 Wang, L., 211 Wang, X., 57, 74 Waubke, H., 35, 36, 37 Weber, F., 212 Wegscheider, M., 89, 101 Weidlinger, G., 134, 138, 146 Weihs, G., 41, 43, 50 Weinwurm, G., 7, 10 Wellenzohn, M., 194 Widhalm, L., 121, 122 Widl, E., 54, 60, 61, 178 Wilflinger, T., 124, 131

221

Wünschek, B., 57, 74 Zederbauer, T., 195

60th annual meeting austrian physical society 6–10 september … · 2010. 9. 6. · 8.4 fakt 54...

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