Decay Spectroscopy Experiments Using the GRIFFIN Spectrometer and Rare Beams Produced at TRIUMF

Transcription

1 SIMON FRASER UNIVERSITY ENGAGING THE WORLD Decay Spectroscopy Experiments Using the GRIFFIN Spectrometer and Rare Beams Produced at TRIUMF Corina Andreoiu Department of Chemistry Simon Fraser University Burnaby, BC, Canada SSNET Workshop Gif sur Yvette, France November 7-11th, 2016

2 Location & Some History UBC SFU SFU Tri-University Meson Facility (TRIUMF) 1968 Simon Fraser University, University of British Columbia and University of Victoria TRIUMF, Canada s National Laboratory for Particle and Nuclear Physics Own and operated by a consortium of Canadian Universities TRIUMF SFU ,000 students 6,500 faculty and staff 130,000 alumni TISOL facility

3 Isotope Separator and Accelerator (ISAC) Highest power for on-line facilities ISAC has 3 main areas: ISAC I 60 kev ISAC II 1.8 MeV A ISAC III > 6 MeV A

4 A close-packed array of 16 large-volume HPGe Clover detectors, 64 crystals GRIFFIN - The Gamma-Ray Infrastructure For Fundamental Investigations of Nuclei Absolute Photopeak Efficiency (%) π GRIFFIN γ-ray Energy (kev) 4096 crystal pairs at 52 unique angles for γ-γ angular correlations a)

5 GRIFFIN Digital DAQ Custom Digital Electronics designed and built at Université de Montreal and TRIUMF Programmable Logic Pulse Generator 32 Channels NIM or TTL Clock Distribution Module 10 MHz Atomic Clock Low-jitter fan-out to all modules 300 MB/s of data to disk GRIF-16 Module 16 chans 100 MHz, 14 bit 4 chans 1 GHz 14 bit GRIF-4G Module Master and Collector Module 650 MB/s link to each digitizer 2 GB RAM with peak transfer of 8.5 Gb/s.

6 First GRIFFIN experiments and results Technical'and'Overview'Paper' U.'Rizwan'et#al.,'NIM'A'820,'126'(2016).' A.B.'Garnsworthy,'Acta'Phys.Pol.'B,'47,'713'(2016).' C.E.'Svensson'and'A.B.'Garnsworthy,'Hyp.'Int.'225,'127'(2014).' Fermi'Super'Allowed'beta' decay'of' 62 Ga' Equilibrium'of' 115 Cd m '' During'the's@process' S1007,' 115 Ag' S1367,' 33@35 Mg' S1457,' 128@132 Cd' S1468,' 145,146 Cs' S1507,' 32 Na' S1518,' 62 Ga' S1519,' 132,133 In' Tests,' 9 Li,' 26 Na' Also,' 47,48 K' Nuclear'structure'around' 132 Sn' R.#Dunlop#et#al.,#PRC#93,#062801(R)#(2016).# Island'of'inversion,' 32 Mg,' 32,33,34 Al' Neutron'single'and'pair' hole'states'in'the' 48 Ca' doubly@closed'shell' 10'beamWmes'scheduled' in'first'2'years.' Over'70'scienWsts'from'12'countries'have'now'joined'the'collaboraWon'

7 The GRIFFIN Spectrometer at TRIUMF Sensitive Decay Spectroscopy ISOBAR J π ISOMER J π GS

8 The GRIFFIN Spectrometer at TRIUMF Sensitive Decay Spectroscopy Fast, in-vacuum tape system Enhances decay of interest ISOBAR J π ISOMER J π GS T 1/2 Longer T 1/2 Shorter T 1/2

9 The GRIFFIN Spectrometer at TRIUMF Sensitive Decay Spectroscopy Fast, in-vacuum tape system Enhances decay of interest ISOBAR T 1/2 Longer J π ISOMER J π GS SCEPTAR: plastic scintillators Detects beta decays and determines branching ratios T 1/2 Shorter T 1/2

10 132 In beta decay Beta-gamma spectra gated on SCEPTAR showing states in 132 Sn. K. Whitmore, SFU Preliminary

11 The GRIFFIN Spectrometer at TRIUMF Sensitive Decay Spectroscopy Fast, in-vacuum tape system GRIFFIN 16 HpGe Clovers Enhances decay of interest Detect gamma rays and ISOBAR T 1/2 Longer J π ISOMER T 1/2 Shorter determines branching ratios, multipolarities and mixing ratios J π GS T 1/2 SCEPTAR: plastic scintillators Detects beta decays and determines branching ratios γ γ γ E,J π τ E,J π τ

12 The GRIFFIN Spectrometer at TRIUMF Sensitive Decay Spectroscopy Fast, in-vacuum tape system Enhances decay of interest ISOBAR T 1/2 Longer J π ISOMER T 1/2 Shorter GRIFFIN 16 HpGe Clovers Detect gamma rays and determines branching ratios, multipolarities and mixing ratios J π GS T 1/2 SCEPTAR: plastic scintillators Detects beta decays and determines branching ratios γ γ γ e - e - E,J π τ E,J π τ α PACES: 5 Cooled Si(Li)s Detects Internal Conversion Electrons and alphas/protons

13 The GRIFFIN Spectrometer at TRIUMF Sensitive Decay Spectroscopy Fast, in-vacuum tape system GRIFFIN 16 HpGe Clovers Enhances decay of interest Detect gamma rays and ISOBAR T 1/2 Longer determines branching ratios, J π ISOMER T 1/2 Shorter multipolarities and mixing ratios J π GS SCEPTAR: plastic scintillators Detects beta decays and determines branching ratios T 1/2 γ γ γ e - e - E,J π τ E,J π τ DANTE: 10 BaF 2 /LaBr 3 Fast-timing of photons to measure level lifetimes α,p PACES: 5 Cooled Si(Li)s Detects Internal Conversion Electrons and alphas/protons

14 Shell evolution in the Ca isotopes

15 Ab-initio interaction; NN + 3N forces

16 Previous beta decay experiments on 46 Ca 46 Ca 0.004% Two previous beta decay experiments from late 1960 s 115(4) s nndc: 105 s 95(5) s B. Parsa and G. Gordon, Phys. Lett. 2, 269 (1966). M. Yagi et al., Laboratory Nucl. Sci., Tohoku Univ. 1, 60 (1968).

17 Excitation energies of bound excited states in 46 Ca J. Holt et al., Phys. Rev. C 90, (2014) Three-nucleon forces and spectroscopy of neutron-rich calcium isotopes

18 The$Experiment$ Use the Beta Decay of 46 K 46 Ca Q = 7716 kev 0.0 kev 46 K 2-4 x 10 5 pps beam 95s K Ca ν e 3609 kev 3020 kev 2574 kev 2421 kev 1346 kev 46 Ca ~40 hours of data collection 0.0 kev GRIFFIN Configuration 15 HPGe Clover Detectors 5 Si(Li) Detectors (PACES) 10 scintillators (SCEPTAR) Moving tape system

19 Observed excited states in 46 Ca 194 gammas observed 150 newly observed 38% 42 total excited states 14 newly observed Weakest gamma ray observed has an intensity % that of the to transition. Branching ratios observed down to % -decay feeding primarily feeds the keV and the 2 (-) 5052 kev state. J.L. Pore (PhD student), Simon Fraser University

20 46 K Half-life Decay of the 1345 kev Gamma Ray Events Compton-Scatter Events Decay Time (s) T 1/2 = 96.41(10) s B. Parsa and G. Gordon, Phys. Lett. 23, 269 (1966). M. Yagi et al., Res. Rep. Lab. Nucl. Sci., Tohoku Univ. 1, No. 2, 60 (1968). P. Kunz, C. Andreoiu, F. Wong, et al., Rev. Sci. Instrum. 85, (2014).

21 The$5052$keV$State$ 46 K$$20$ Gate % (4 ) Angular Correlation Investigate Spin Assignment 4096 crystal pairs at 52 unique angles for γ-γ angular correlations W (θ) =1+ A 2 P 2 (cosθ)+ A 4 P 4 (cosθ)

22 3706%1346(Cascade( Theo. Exp. Compare to theoretical predictions. 2 (-) (4 ) a χ 2 /ν cascade b χ 2 /ν = cascade W (θ) =1+ A 2 P 2 (cosθ)+ A 4 P 4 (cosθ) 22

23 46 Ca theory & experiment J. Holt, private communication and Phys. Rev. C90, (2014) Quantum Monte Carlo with chiral EFT interactions It includes excitations from the s1/2 and d3/2 orbitals

24 Beta%Feeding%Systema/cs% 46 K 4-40 K K (2 ) (18% ) K (2 ) 4409 (28% ) (2% ) K (38% ) (2 ) 7400 (23% ) (31% ) K (2 ) (2 ) Ca 42 Ca 44 Ca 46 Ca 48 Ca (89% ) (82% ) (34% ) (0% ) (<1% ) 0 (21% ) (16% ) 4506 (6% ) π ν π 46 Ca 20 ν Why is this decay hindered? f 7/2 d 3/2 s 1/2 f 7/2 d 3/2 s 1/2 24

25 Evolu&on(of(sd*shell(in( 19 K(Isotopes( Ground-state configurations 48 K : π s 1/2 and π d 3/2 orbitals believed to be nearly degenerate π1d 1 1 3/2 ν1f 7/2 46 K: no unique structure predicted J. Papuga et al., Phys. Rev. C 90, (2014). 25

26 Excited states in even-a K (1,2,3) K 42 K 44 K 46 K 48 K

27 32 Na decay to excited states in 32 Mg Island of inversion at N=20 8pi: 2-3 pps, 5 days GRIFFIN: ~9 pps, ~2 days F. Sarazin, Colorado School of Mines, USA

28 32 Mg γ γ coincidences [883,887] kev 2152 kev N γγ = kev N γγ = kev N γγ = kev N γγ = kev N γγ = kev N γγ =986

29 Detailed Spectroscopy of 132 Sn New$Transi+ons$in$ 132 Sn$ Experiment performed in July 2016 K. Whitmore, Simon Fraser University

30 Summary I Critical information on shell structure effects can be obtained from semi-magic nuclei close and far to stability. They can challenge and benchmark the nuclear models of structure and give hints about the nuclear interaction. The GRIFFIN spectrometer is a powerful tool for detailed decay studies. TRIUMF approved investigations of 52 Ca, 53 Ca, and 54 Ca with GRIFFIN. ARIEL - new driver; photo-fission; n-rich factory

31 Summary II GRIFFIN + DESCANT for beta-delayed neutron decays

32 Summary III Compton suppression shields for GRIFFIN GEANT4-simulated GRIFFIN spectra without/with suppression shields Compton suppression and background shields funded by: The Canadian Foundation for Innovation The Ontario Ministry of Science British Columbia Knowledge and Development Fund

33 Thanks'to'Collaborators' C. J.L. Andreoiu, Pore, D.S. Cross, F. Garcia, K. Whitmore, K. Ortner, K. Starosta, A. Chester, J. Williams, T. Domingo Simon Fraser University, Canada G.C. Ball, P. Bender, N. Bernier, D. Bishop, M. Bowry, D. Brennan, T. Bruhn, R. Caballero, A. Cheeseman, R. Churchman, B. Davids, L. Evitts, I. Dillmann, A.B. Garnsworthy, S. Georges, G. Hackman, S. Hallam, J. Henderson, R. Kokke, R. Kruecken, K. Leach, Y. Linn, C. Lim, L. MacConnachie, D. Miller, W.J. Mills, L.N. Morrison, M. Moukaddam, C.A. Ohlmann, O. Paetkau, J. Park, C.J. Pearson, M.M. Rajabali, P. Ruotsalainen, B. Shaw, J. Smallcombe, J.K. Smith, D. Southall, C. Unsworth, Z.M. Wang, S. Wong, TRIUMF, Canada H. Bidaman, V. Bildstein, P. Boubel, C. Burbadge, G. Deng, A. Diaz Varela, R.A. Dunlop, M. Dunlop, P.E. Garrett, B. Hadina, B. Jigmeddorj, D. Kisliuk, A. Laffoley, A. MacLean, E. McGee, B. Olaizola Mampaso, A. Radich, E.T. Rand, C.E. Svensson, J. Turko, T. Zidar, University of Guelph, Canada J-P. Martin, Universite de Montreal, Canada R. Braid, S. Ilyushkin, K. Kuhn, W. Moore, F. Sarazin Colorado School of Mines, USA E. Peters, S. Yates University of Kentucky, USA C. Petrache, University of Paris-Sud, France and the other members of the GRIFFIN collaboration