(the future of) she chemistry with sisak · 2000 - 257the transactinide rf detected with sisak...
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06.03.2012
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Presented at PacifiChem 2010 by
Jon Petter Omtvedt Honolulu, December 2010.
(The Future of)
SHE Chemistry with SISAK
Slide 2 J.P. Omtvedt, PacifiChem 2010, Honolulu, December 2010
Outline
● What is SISAK?
● 10 years of SISAK SHE research ● Summary of results
● Experience gained
● The (SISAK) future... ● Capabilities
● Requirements
● Organisation and Logistics
● Conclusions
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Slide 3 J.P. Omtvedt, PacifiChem 2010, Honolulu, December 2010
SISAK Oslo Group and Collaborators
Project leader: Prof. Jon Petter Omtvedt Senior scientists: Prof. Jorolf Alstad and Prof. Tor Bjørnstad.
Post docs: Dr. Karsten Opel, Dr. Alexey Sabelnikov, Dr. Nalinava Sen Gupta.
PhDs: Marcus Johansson (2000), Liv Stavsetra (2005), Li Zheng (2007), Fereshteh Samadani (2010), Darina Polakova (on-going).
Masters: Kristin Fure (1998), Liv Stavsetra (1999), Elin A. Hult (1999), Jan-Erik Dyve (2000), Hanne Breivik (2001), Fereshteh Samadani (2006), Beyene G. Haile (2008), Frøydis Schulz (2009), Johannes Nilsen (2009).
Key collaborators: Prof. Darleane Hoffman (LBNL), Dr. Ken Gregorich (LBNL), Prof. Heino Nitsche (LBNL), Dr. Matthias Schädel (GSI), Dr. Christoph Düllmann (GSI), Prof. Gunnar Skarnemark (Chalmers), Dr. Klaus Eberhardt (U. Mainz), Dr. Norbert Trautmann (U. Mainz).
Many others: Students, technicians and other personnel at Oslo, LBNL, Mainz and GSI.
Slide 4 J.P. Omtvedt, PacifiChem 2010, Honolulu, December 2010
Outline
● What is SISAK?
● 10 years of SISAK SHE research ● Summary of results
● Experience gained
● The (SISAK) future... ● Capabilities
● Requirements
● Organisation and Logistics
● Conclusions
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Slide 5
Liquid-liquid Extraction System SISAK
SISAK = Short-lived Isotopes Studied by the AKUFVE- technique
AKUFVE is a Swedish acronym for an arrangement for continuous investigations of distribution ratios in liquid-liquid extraction.
Slide 6
SISAK Liquid-liquid Extraction System
● AKUFVE ● Distribution ratios ● Continuous flow
● Fast
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Slide 7
SISAK Liquid-liquid Extraction System
● AKUFVE ● Distribution ratios ● Continuous flow
● Special centrifuges
● Fast Separation chamber
Inlet/outlets
Rotating cup
Slide 8
SISAK Liquid-liquid Extraction System
● AKUFVE ● Distribution ratios ● Continuous flow
● Special centrifuges
● Fast Phase boundary
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Slide 9
SISAK Liquid-liquid Extraction System
● AKUFVE ● Distribution ratios ● Continuous flow
● Special centrifuges Centrifuge (H-10) developed in Gothenburg in the 1970s.
Application and further development by a Gothenburg-Oslo-Mainz collaboration.
Separation chamber volume reduced with each generation:
- 120 mL → 12 mL → 0.3 mL
Reinhardt & Rydberg, JActaChemScand 23 (1969) p2773. Persson et al. RCA48, (1989) p177. Commercialized by Swedish company MEAB AB.
● Three generations
● 0.3 mL chamber
● Fast
Slide 10
SISAK Liquid-liquid Extraction System
● AKUFVE ● Distribution ratios ● Continuous flow
● Special centrifuges
● Three generations
● 0.3 mL chamber
● Fast
PEEK centrifuges developed in Oslo for SHE chemistry studies in the 1990s
● PEEK
● Two types: → liquid-liquid → gas-liquid
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Slide 11
SISAK Liquid-liquid Extraction System
● AKUFVE ● Distribution ratios ● Continuous flow
● Special centrifuges
● Three generations
● 0.3 mL chamber
● Fast
Standard setup with degasser and main extraction stage
● PEEK
● Two types: → liquid-liquid → gas-liquid
Omtvedt et al., J. Alloys & Comp. 271–273 (1998) p303.
Slide 12
On-line Liquid Scintillation α-detection
Outlet
Inlet
Light guide
PMT
Scintillationchamber
150 200 250 300 350 4000
200
400
600
800
1000
Co
un
ts/c
han
nel
Channel
219Rn,6.82 MeV
+6.55 MeV
215Po,7.39 MeV Wierczinski et al., NIM A 370 (1996) p532.
Wierczinski et al., Radioan. Nucl. Ch. 247 (2001) p57. Stavsetra & Omtvedt, Radiocarbon (2002) p24. Stavsetra, Hult & Omtvedt, NIM A 551 (2005) p323. Stavsetra et al., NIM A 543, (2005) p509.
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Slide 13
Preseparation w. RTC
Berkeley Gas-filled Seperator (BGS) ●Preseparations removes unwanted background.
●Recoil Transfer Chamber (RTC).
●Allows chemical experiment to focus on chemical properties, not separation.
●Makes α liquid-scintillation detection possible.
Developed at LBNL by Kirback & Gregorich. Kirback et al., NIM A 484 (2002) p587. Omtvedt et al., J. Nucl. RadioSci. 3 (2002) p121.
Slide 14
Full SISAK system for SHE
Degasser
Aq.phaseExtraction
MainExtraction
Ar flushing
Ar flushing
Aq
.ph
ase
Org. phase
Gas jet
Aq. phase
Org. phase
Org.phase
Scintillator
Scintillator
Todetectors(organicphase)
Todetectors(aqueous
phase)
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Slide 15
Full SISAK system for SHE
Slide 16 J.P. Omtvedt, PacifiChem 2010, Honolulu, December 2010
Outline
● What is SISAK?
● 10 years of SISAK SHE research ● Summary of results
● Experience gained
● The (SISAK) future... ● Capabilities
● Requirements
● Organisation and Logistics
● Conclusions
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Slide 17
2000 - The transactinide 257Rf detected with SISAK liquid scintillation
detectors, proved that studying SHE with SISAK is possible.
2001 - Rf extracted from 6 HNO3 into toluene with HDBP, first SISAK
chemistry experiment on a SHE.
- Rf extracted from oxalic acid into toluene with TOA.
2003 - Rf extracted from sulphuric acid into toluene with TOA.
2005 - Rf extracted from H2SO4, simultaneous detection of both
phases enhances yield and precision.
2006-7 - Knowledge from BGS-RTC used in building two RTC’s for
TASCA, one large and one small.
2008 - New small RTC built for BGS
- 258Db detected with SISAK LS-detection system.
2009 - First GSI experiment with SISAK@TASCA, testing Hs-chemistry with Os.
SISAK achievements 2000-2009
Results of a Oslo-LBNL-Gothenburg-Mainz collaboration
Achievements 2000-2010
Slide 18
Important Improvements 2000
2005
Premixer
Only one throttle
Org. feed
0.7 mm (i.d.) tubes
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Slide 19
Equilibrium condition → Premixer
●Phases must be mixed thoroughly enough to ensure extraction under equilibrium conditions.
●Slow kinetics will lead to severe decay loss.
●Efficient mixing very important!
Extraction of OsO4 into toluene, from Samadani et al., RCA98 (2010) (DOI 10.1524/ract.2010.1787)
Slide 20
Equilibrium Extraction
●System for investigating Hs
●Developed with γ-emitting Os (OCL) and α-emitting Os (GSI).
Samadani, PhD thesis Univ. Oslo (2010). Samadani et al., RCA 98 (2010) p757. Samadani et al., to be submitted to RCA.
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Slide 21 J.P. Omtvedt, PacifiChem 2010, Honolulu, December 2010
Outline
● What is SISAK?
● 10 years of SISAK SHE research ● Summary of results
● Experience gained
● The (SISAK) future... ● Capabilities
● Requirements
● Organisation and Logistics
● Conclusions
Slide 22
The Future?
● Good chemistry cases:
- Take full advantage of the freedom offered by preseparation.
- Must be interesting for theoreticians.
- Must be clearly understood (equations known).
- Fast kinetics.
● Reliability and ease of operation.
- Less maintenance and fewer break-downs.
- Replace degassers with membrane separation units.
● Logistics and man-power
- Need collaboration with an accelerator lab with a local SISAK group/students or at least liquid-phase chemistry group.
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Slide 23
Prototype Membrane Degasser
●Teflon membrane with 0.25-1.0 μm pore size.
●Phase separation adjusted with throttle on liquid outlet.
MSc thesis work of J. Nilssen (2009).
Slide 24
Prototype Membrane Degasser (MDG)
●Teflon membrane with 0.25-1.0 μm pore size.
●Phase separation adjusted with throttle on liquid outlet.
●Tested with - 0.2-0.9 Bar suction Flow decrease
from 0.37 to 0.09 mL/s severely
reduces the gas to liquid transfer.
Unexpectedly much better
than centrifuge degasser (fitted
with mixer)!
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Slide 25
Prototype MDG with premixer
●A mixer in front of the degasser increases transfer.
- But will also slow down transport.
●Many different mixers developed through the years
- Zigzag pattern & - PEEK wool the most effective.
Slide 26
Prototype Membrane Degasser (MDG)
Fitting a mixer to MDG did not help, but was
only tested with 1 μm membane.
●A mixer in front of the degasser increases transfer.
- But will also slow down transport.
●Many different mixers developed through the years
- Zigzag pattern & - PEEK wool the most effective.
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Slide 27
Full SISAK with MDGs…
Degasser
Aq.phaseExtraction
MainExtraction
Ar flushing
Ar flushing
Aq
.ph
ase
Org. phase
Gas jet
Aq. phase
Org. phase
Org.phase
Scintillator
Scintillator
Todetectors(organicphase)
Todetectors(aqueous
phase)
●Reduction from five to two centrifuges.
Slide 28
Cryptans
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Slide 29
How Heavy SHE can SISAK handle?
SHE experiments with rutherfordium not regarded as particularly difficult anymore. SISAK has only done chemistry experiments with rutherfordium….
But:
“Normal” experiments used 1-min 261Rf, SISAK used 4-s 257Rf....
No other liquid phase chemistry has tackled 4-s SHE. For SISAK, the difference between Rf, Db, Sg, Bh and Hs is about cross-section and decay pattern, not half life.
Slide 30 J.P. Omtvedt, PacifiChem 2010, Honolulu, December 2010
Conclusions
● SISAK can handle Rf, Db, Sg without problem.
● SISAK might handle Bh and Hs.
● A stable, two-person per shift system can be built
– no new science, just technology.
● To justify the investment a (very) good chemistry case must be identified
– close collaboration with theorists necessary.
● Dedicated effort at one lab necessary
– will most likely require local SISAK group.
● SISAK detector system very effective and true on-line
– can be used for other liquid phase experiments.
● Funding a major issue, as always.
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