gerçekles¸tirildi: madde, anti-madde, saf enerji ve simya...

Intro Setup Results Summary

(Ülkemizin ilk fotonükleer reaksiyonu Akdeniz Üniversitesinde

gerçeklestirildi: Madde, Anti-Madde, Saf Enerji ve Simya)

Turkey’s first photonuclear reactionsperformed at Akdeniz University: Matter,Anti-matter, Pure Energy and Alchemy

http://mistug.tubitak.gov.tr/bdyim/kabul.php?dergi=fiz

Haris Ðapo(Ismail Boztosun)

Akdeniz University, Antalya

IZYEF 2013 • Izmir, September 2013


Outline

1 Introduction

2 Method and setup

3 Results

4 Summary and Outlook


Introduction

Photonuclear reactions• photonuclear reactions describe a set of interactions

between nuclei and photons, most commonly separation ofeither from the nucleus

• since the realization that nuclei are not fundamentalpoint-like particles (In 1932, James Chadwick discoveredneutron) the possibility of removing a neutron or a protonfrom nucleus arose

• separating a neutron of a proton from stable nucleusrequires several MeV of energy (one commonly needs10 MeV)

• producing a photon of 10 MeV energy took few decades

• most commonly the start of photonuclear reactions isassociated with construction and operation of SLAC(Stanford Linear Accelerator Center) in 1960’s


Nucleide Map


Photonuclear reactions

Various cases• photonuclear reactions change one element into another

(Alchemy)

• if a neutron is removed a proton rich nucleus is createdand it decays via β+ decay back to valley of stability

• β+ decays produce positrons and characteristic anhilationpeak at mass of electron of 511 keV is observed(Anti-Matter)

• proton rich nuclei are not accessible via neutron absorption

• if proton is removes a neutron rich nucleus is created and itdecays via β−

• if photons is absorbed a metastable stable version of thesame element is created


Photonuclear reactions in detail

Generic

γ +NZ A →

N−1Z A − 1 + n

γ +NZ A →

N−1Z A − 1∗ + n

γ +NZ A →

NZ A − 1 + p

Zinc example

γ +64 Zn →63Zn + n

γ +70 Zn →69Zn∗ + n

γ +68 Zn →67Cu + p


Outline

1 Introduction

2 Method and setup

3 Results



Experiment stages

Shot description

• first the sample is irradiated in the linac at the AkdenizUniversity’s hospital

• sample is transported from the hospital to the physicsdepartment

• irradiated sample is counted in a detector

• counts are stored at appropriate time intervals

• once the counting is finished, background subtraction isperformed

• background subtracted spectrum is analyzed peak by peak

• transition energies are obtained at this point

• counts from each peak are correlated with the time stamp

• a fit of counts vs. time is performed

• half-life is obtained at this point


Photonuclear reactions with linear accelerators

LINAC• linear accelerators can produce photons by bombarding a

Tungsten, or and high-Z, target with electrons

• photons are than produced trough bremssthralungand have thecharacteristicspectrum

• on the right:bremssthralungspectrumwith 18 MeVend-pointenergy


Linear accelerators

cLINAC• photonuclear experiments involving linacs are routinely

performed around the world

• but the use of clinical linac(cLINAC) for this purpose is anovel concept

• modern cLINAC found in radiation treatment facilities arecapable of producing bremsstrahlung photons withendpoint energies up to 25 MeV and compare well tospecialist setups such as S-DALINAC at TU Darmstadt orELBE at Forschungszentrum Dresden in Rossendorf

• for the most part photonuclear measurement are notincluded in NUDAT, especially so for intermediate massnuclei

11pioneering experiment on gold: P. Mohr, S. Brieger, G. Witucki, and M.

Maetz, Nucl.Instrum.Meth. A580, 1201 (2007), 0707.2933.


Our linac setup

Philips SLi-25

• current end-point energy is 18 MeV, although linac canoperate at lower energies as well

• in the future we plan to bring online 25 MeV end-pointenergy

• primary electron beam is generated by a gun with anenergy of 50 keV

• electrons are accelerated in a copper cavity by a 30 GHzradio-frequency with peak power of about 5 MW

• steering and focusing of the beam is achieved by standardmagnetic and electrostatic devices

• beam current is 30 µA for 18 MeV

• once collimated and flattened at a distance of 100 cm, themaximum area covered by photons is 40×40 cm2


Linac schematic


The detector

High Purity Germanium Detector(HPGe)

• p-type, coaxial, electrically cooled, HPGe gamma-rayspectrometer with 40% relative efficiency and 768 eVFWHM at 122 keV for 57Co and 1.85 keV FWHM at1332 keV for 60Co

• samples and the detector, were placed into a well-shieldedcavity

• the detector is connected to the usual NuclearInstrumentation Module for data acquisition

• calibration was performed with a source supplied by theÇekmece Nuclear Research and Training Center

• detector was configured with 8192 channels and theresulting energy resolution was 0.33954 keV (currently16383 channels and 0.169 keV resolution)


Full reactions

Generic

γ +NZ A →

N−1Z A − 1 + n

N−1Z A − 1 →

NZ−1A − 1∗ + e+ + ν

NZ−1A − 1∗

→NZ−1A − 1 + γ

γ +NZ A →

N−1Z A − 1∗ + n

N−1Z A − 1∗

→N−1Z A − 1 + γ

γ +NZ A →

NZ−1A − 1 + p

NZ−1A − 1 →

N−1Z A − 1∗ + e− + ν

N−1Z A − 1∗

→N−1Z A − 1 + γ

Zinc example

γ +64 Zn →63Zn + n

63Zn →63Cu∗ + e+ + ν

63Cu∗→

63Cu + γ

γ +70 Zn →69Zn∗ + n

69Zn∗→

69Zn + γ

γ +68 Zn →67Cu + p

67Cu →67Zn∗ + e + ν

67Zn∗→

67Zn + γ

γ +66 Zn →65Zn + n

65Zn →65Cu∗ + e+ + ν

65Cu∗→

65Cu + γ


The observations

The description of detection

A stable element is exposed to linac gamma-rays. A radioactiveelement is produced. The element decays trough gamma orbeta decay. Gamma decay is directly observed. In case of betadecay daughter nuclei are created in excited states and thanthe daughter decays trough gamma-decay to its ground state.The time-dependance of decay is linked to the half-life of theparent. In all cases only gamma-transition are observed.

Notes• in principle all nuclei go trough photonuclear reactions, but

only those whose neighbor is radioactive can be observedin our setup

• in addition more practical restrictions apply, like: length ofhalf-life, observability of daughter states, etc.


The analysis tool

GF3• GF3 is a least-squares peak-fitting program designed

primarily for use in analyzing gamma-ray spectra fromGermanium detectors

• GF3 fits three components to each peak: a Gaussian, askewed Gaussian and a smoothed step function toincrease the background on the low-energy side

• the Gaussian, is the main component of the peak

• the skewed Gaussian, arises fromincomplete charge collection

• the step function arises mainlyfrom Compton scattering ofphotons into the detector andfrom escape of photoelectronsfrom the Ge crystal


Outline

1 Introduction

2 Method and setup

3 Results



Cu-63 transition energies

Data• NUDAT: 669.62±0.05 keV;

962.06±0.04 keV

• Our result:669.58±0.02keV and 962.10±0.02 keV

100

101

102

103

104

665 670

Cou

nts

per

keV

E[keV]

t=2315 st=700 st=140 s

955 960 965

E[keV]

t=2315 st=700 st=140 s


Zn-63 decay curve

0

2000

4000

6000

8000

10000

12000

14000

0 250 500 750 1000 1250 1500 1750 2000 2250

Net

cou

nts

t[s]

669 keV962 keVfit(669),N0=27.4e3,λ=2.83e-3fit(962),N0=14.2e3,λ=3.34e-3

Data• NUDAT: 38.47±0.05 min

• Our result: 40.8±0.6 min (669 peak)and 34.6±0.7 min (962 peak)


Zn-67 transition energies

Data• NUDAT: 184.577±0.010

keV; 300.219±0.010 keV

• Our measurement:184.273±0.005 keV;300.04±0.23 keV

102

103

104

105

184 186

Cou

nts

per

keV

E[keV]

t=86126 st=23703 st=4837 s

298 300

E[keV]

t=86126 st=23703 st=4837 s


Cu-67 decay curve

0

50000

100000

150000

200000

250000

0 10000 20000 30000 40000 50000 60000 70000 80000 90000

Net

are

a

t[s]

x50

184 keV300 keVfit(184),N0=98.8e4,λ=3.19e-6fit(300),N0=3.3e4,λ=9.9e-7

Data• NUDAT: 61.83±0.12 h

• Our result: 60.3±0.6 h (184 peak)and 197±73 h (300 peak)


Zn-69m and Cu-65 transition energies

100

101

102

103

104

105

435 440

Cou

nts

per

keV

E[keV]

t=86126 st=23703 st=4837 s

1110 1115 1120

E[keV]

t=86126 st=23703 st=4837 s

Data• NUDAT:

438.614±0.018 keV; 1115.546±0.004 keV

• Our:438.512±0.005 keV; 1115.696±0.008 keV


Zu-69m decay rate

0

50000

100000

150000

200000

250000

300000

350000

400000

450000

0 10000 20000 30000 40000 50000 60000 70000 80000 90000

Net

are

a

t[s]

438 keVfit(438),N0=63.30e4,λ=14.23e-6

Data• NUDAT: 13.74±0.02 h

• Our result: 13.51±0.03 h


Zu-65 decay rate

0

50000

100000

150000

200000

250000

0 10000 20000 30000 40000 50000 60000 70000 80000 90000

Net

are

a

t[s]

1115 keVfit(438),(N0*λ)=2.462

Data• NUDAT: 243.93±0.09 days

• Only 1 day of observation is not sufficient for 244 daydecay


Outline

1 Introduction

2 Method and setup

3 Results



Summary

The road so far• photonuclear reactions with cLINAC are real possibility

• first experiment of photonuclear reaction performed inTurkey

• performed with local resources, staff and capabilities

• at the very first attempt data accuracy was reasonable

• and with every day we are getting better

• but the real testament to our achievement and a realsummary is all the data we have gathered and shown


Summary

The road so far• photonuclear reactions with cLINAC are real possibility

• first experiment of photonuclear reaction performed inTurkey

• performed with local resources, staff and capabilities

• at the very first attempt data accuracy was reasonable

• and with every day we are getting better

• but the real testament to our achievement and a realsummary is all the data we have gathered and shown

What did not fit into the talk• since may we have performed several new experiments on

various nuclei

• Cu, Ni, Ti, Pb, In, Hg, etc.

• but the hard part, the data analysis is still pending


Outlook

To be continued, stay tuned

• solve the systematic accuracy issue

• find new elements which would be best suited for futureexperiments

• upgrade the accelerator to 25 MeV (software issue)

• build an online multi detector setup capable of measuring(γ, γ′) reactions

• with new setup investigate the collective behavior of nuclei(GDR, PDR, etc.)


Our group

Collaborators on this project:Ismail Boztosun,Haris Ðapo, Süleyman Fatih Özmen,Yigit Çecen, Mesut Karakoç, Abdullah Çoban,Alp Cesur,Tanfer Caner, Edip Bayram, Gizem B. Keller, Beyza Kücük,Abdullah Güvendi,Melek Derman and Deniz Kaya


Thank you for yourattention!

gerçekles¸tirildi: madde, anti-madde, saf enerji ve simya...

Documents