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The 8pi and TIGRESS Gamma-Ray Facilities at TRIUMF

The 8pi and TIGRESS Gamma-Ray Facilities at TRIUMF. Greg Hackman, TRIUMF Gamma ’08, RIKEN 2008-04-04 13:20-13:50 . 8pi & TIGRESS in a nutshell. TIGRESS High Energy-Resolution Gamma-Ray Array Optimized for in-beam spectroscopy of 1%< β <10% RIBs

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The 8pi and TIGRESS Gamma-Ray Facilities at TRIUMF

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  1. 8pi & Tigress, Hackman, Gamma08, RIKEN

  2. The 8pi and TIGRESS Gamma-Ray Facilities at TRIUMF Greg Hackman, TRIUMF Gamma ’08, RIKEN 2008-04-04 13:20-13:50

  3. 8pi & Tigress, Hackman, Gamma08, RIKEN 8pi & TIGRESS in a nutshell TIGRESS • High Energy-Resolution Gamma-Ray Array • Optimized for in-beam spectroscopy of 1%<β<10% RIBs • Recent result: Effective charges in 21Ne,Na ep>>1.5e, en<<0.5e • New array, digital electronics • Installed on ISAC-II beamline(s) • 6 installed clovers, 4 in acceptance testing, 3 to complete order • 4 crystals/unit, 8-segment cathode • 0.8% per installed unit • (Triumf-Isac Gamma-Ray Escape Suppressed Spectrometer) 8pi • High Energy-Resolution Gamma-Ray Array • Optimized for precision transition rate measurements of decaying nuclei • Recent result: Superallowed Branching Ratio in 38mK is 99.967(4)% • Old array, conventional electronics • Installed on low-energy (<60 keV) beamline • 20 escape-suppressed single-crystal single-cathode HPGe • 0.1% photopeak efficiency

  4. 8pi & Tigress, Hackman, Gamma08, RIKEN 38mK Superallowed Branching Ratio K.G. Leach, D. Bandyopadhyay, P. Finlay, P.E. Garrett, G.F. Grinyer, A.A. Phillips, M.A. Schumaker, C.E. Svensson, J. Wong University of Guelph G.C. Ball, E. Bassiachvilli, S. Ettenauer, G. Hackman, A.C. Morton, S. Mythili, O. Newman, C.J. Pearson, M.R. Pearson, H. Savajols TRIUMF J.R. Leslie Queens University D. Melconian University of Washington R.A.E. Austin St. Mary's University C. Barton University of York

  5. 38mK Small βBranch [2] 0+ 0+ T =1 3+ T =0 2+ 38K E γ =1210 keV 0+ SuperallowedβBranch > 99.998% [2] T =1 E γ =2167 keV 38Ar 8pi & Tigress, Hackman, Gamma08, RIKEN 38mK Superallowed Branching Ratio Motivation • World average of superallowed Fermi beta decay transition rates are an input to Vud element of CKM quark mixing matrix element [1] • 38mK most accurately measured [2] – until now • Reported experimental uncertainties in line with assumed uncertainties in competing corrections, especially nuclear structure dependent parts • Goal of this experiment: measure non-analogue Fermi branch (expected to be 6×10–6 [1]) with 8pi • Surprise found along the way [1] Towner & Hardy, PRC 77, 025501 (2008) [2] Hagberg et al, PRL 73, 396 (1994) report <19×10–6 at 1σ level

  6. 8pi & Tigress, Hackman, Gamma08, RIKEN TRIUMF-ISAC facility: production, ISAC-I experimental hall with equipment, and ISAC-II accelerators • 33 kW protons • Ta target • Re surface ionizer • A/q=38 separator • 40000 38mK/s • Plus 38mCl, 38K….

  7. 8pi & Tigress, Hackman, Gamma08, RIKEN Use the 8pi to Measure Non-Analogue Decay • In addition to HPGe:: • Endless loop moving tape system • US DoE, Louisiana State University • Programmable states (beam on/off, tape move, trigger veto) • Options: Inner scintillator array, SiLi (beta tagging vs. conversion electron measurement) • Recently added BaF2 in gaps between HPGe

  8. 1.0s <t< 1.6s – Background acquisition 1.6s <t< 5.1s – Beam implantation 5.1s <t< 6.1s – Decay counting t1/2=929 ms (38mK) t1/2=458 s (38K) 8pi & Tigress, Hackman, Gamma08, RIKEN Beta decay timing • Program: • Move tape (not shown – triggers vetoed) • Background • Implantation • Decay • Scintillator hits counted by high-speed time-slice scalers • Shown: sum of ~60,000 cycles • 2 billion decays

  9. 8pi & Tigress, Hackman, Gamma08, RIKEN Gamma spectra Top curve: all γ Bottom: γ with βγ time coincidence γ with β veto Room background + !!!! γ with βγ time coincidence 90% CL on “expected” non-analogue branch is 12×10–6

  10. 8pi & Tigress, Hackman, Gamma08, RIKEN What is that 130 keV line? • 4100(160) counts • Eγ=E*(38mK) • Does it have a time structure? • Time from beginning-of-cycle recorded for every gamma ray • Gate on 130 keV, project time, fit • MATCHES 38mK SCINTILLATOR (β-DECAY) TIME STRUCTURE

  11. 38mK Total“Internal”Branch 237(31) ×10–6 Even Smaller βBranch 0+ 0+ 3+ 38K E γ =1210 keV 2+ SuperallowedβBranch99.967(4) 0+ T =1 E γ =2167 keV 38Ar 8pi & Tigress, Hackman, Gamma08, RIKEN It’s the 38mK →38K γ Decay • Non-superallowed branch 16 times larger than previous upper limit • … but changes corrected Ft value for 38mK by 1σ • Re-evaluation of global Vud still a work in progress • Penning-trap mass measurements have changed other cases by 1σ Work of Kyle Leach, University of Guelph, et al. Submitted to PRL

  12. 8pi & Tigress, Hackman, Gamma08, RIKEN 21Ne,Na Coulomb Excitation • M.A. Schumaker1, A. Andreyev2, R.A.E. Austin3, G.C. Ball2, D. Bandyopadhyay1, J.A. Becker4, A.J. Boston5, H.C. Boston5, R. Churchman2, F. Cifarelli2, D. Cline6, R.J. Cooper5, D.S. Cross7, D. Dashdorj8, G.A. Demand1, M.R. Dimmock5, T.E. Drake9, P. Finlay1, A.T. Gallant3, P.E. Garrett1,2, K.L. Green1, A.N. Grint5, G.F. Grinyer1, G. Hackman2, L.J. Harkness2,5, A.B. Hayes6, R. Kanungo2, K.G. Leach1, G. Lee2,9, R. Maharaj2, J-P. Martin10, F. Moisan11, A.C. Morton2, S. Mythili2,12, L. Nelson5, O. Newman2,13, P.J. Nolan5, E. Padilla-Rodal2, C.J. Pearson2, A.A. Phillips1, M. Porter-Peden14, J.J. Ressler7, R. Roy11, C. Ruiz2, F. Sarazin14, D.P. Scraggs5, C.E. Svensson1, J.C. Waddington15, J.M. Wan7, A. Whitbeck6, S.J. Williams2, J. Wong1, C.Y. Wu4 1Department of Physics, University of Guelph, Guelph, Ontario, N1G 2W1, Canada 2TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, V6T 2A3, Canada 3Department of Astronomy and Physics, St. Mary's University, Halifax, NS, B3H 3C3, Canada 4Lawrence Livermore National Laboratory, Livermore, California, 94551, U.S.A. 5Department of Physics, University of Liverpool, Liverpool, L69 7ZE, U.K. 6Department of Physics and Astronomy, University of Rochester, Rochester, NY, 14627, U.S.A. 7Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada 8Department of Physics, North Carolina State University, Raleigh, North Carolina, 27695, U.S.A. 9Department of Physics, University of Toronto, Toronto, Ontario, M5S 1A7, Canada 10Département de Physique, Université de Laval, Québec, Québec, G1K 7P4, Canada 11Département de Physique, Université de Montréal, Montréal, Québec, H3C 3J7, Canada 12Department of Physics and Astronomy, University of British Columbia, BC, V6T 1Z1, Canada 13Department of Physics, University of Surrey, Guildford, Surrey, GU2 7XH, U.K. 14Physics Department, Colorado School of Mines, Golden, Colorado, 80401, U.S.A. 15Department of Physics, McMaster University, Hamilton, Ontario, L8S 4L8, Canada • Funding provided by: • Natural Sciences and Engineering Research Council of Canada • U.S. Department of Energy through University of California, Lawrence Livermore National Laboratory • U.S. Department of Energy • U.S. National Science Foundation • U.K. Engineering and Physical Sciences Research Council

  13. d5/2 p1/2 p3/2 8pi & Tigress, Hackman, Gamma08, RIKEN 21Ne,Na Coulomb Excitation Motivation • “Simple” but collective mirror nuclei • 5p configuration outside 16O core • B(E2) to first excited state should be simple to reproduce in shell model, even standard USD • Prior experimental data ... A pretty meaningless test. 8 8 16O 2 2 s1/2 [1] N. Orce, priv. comm.; based on “Oxbash for Windows”, B.A. Brown et al, MSU-NSCL report # 1289, and B.A. Brown & W.A. Richter, PRC 74 034315 (2006) [2] R.B. Firestone, NDS 103, 269 (2004), and Oct 16, 2006 NNDC online erratum

  14. 8pi & Tigress, Hackman, Gamma08, RIKEN 21Ne,Na Coulomb Excitation Motivation • Previous measurements based on lifetimes and M1/E2 mixing ratio from gamma-ray angular distributions • Side notes on 21Na: • Important in stellar burning scenarios [2] • Discrepancy in β-ν correlations vs. standard model in decay [3] • Intermediate-energy pickup has been studied [4] [1] R.B. Firestone, NDS 103, 269 (2004), and Oct 16, 2006 NNDC online erratum [2] C. Ruiz et al., PRC 71, 025802 (2005); J.M. D’Auria et al., PRC 69, 065803 (2006); W. Bradfield-Smith et al., PRC 59 (1999), 3402; A.M. Mukhamedzhamnov et al, PRC 73, 035806 (2006) [3] V. Iacob et al., PRC 74, 015501 (2006) [4] A. Gade et al., PRC 76, 061302(R) (2007)

  15. 8pi & Tigress, Hackman, Gamma08, RIKEN Use TIGRESS to measure gamma yield in 21Ne,Na + natTi scattering Analyze data with GOSIA Fall 2009 July 2007 Jan 2007 Fall 2008

  16. 8pi & Tigress, Hackman, Gamma08, RIKEN TIGRESS & BAMBINO • Gamma array funded for 12 clovers • Frame can handle 16 • Front “lampshade” can be removed for downstream recoil devices • Also shown: BAMBINO • CD-style detector • 16 phi, 24 theta segments • Covers 20 to 50 deg, lab • Earlier than this picture: 2 clovers and Bambino used for 21Ne,Na • Scatter off natTi • Well known B(E2) in 48Ti • Use as “standard” a la REX-ISOLDE and others

  17. 8pi & Tigress, Hackman, Gamma08, RIKEN 21Ne, 21Na Spectra

  18. 8pi & Tigress, Hackman, Gamma08, RIKEN GOSIA Analysis θ-Dependent Fits: Beam Particle Excitation 21Ne 21Na • 6 θ-angle regions • 4 from beam particle detection (forward angles) • 2 from target particle detection (backward angles)

  19. 8pi & Tigress, Hackman, Gamma08, RIKEN θ-Dependent Fits: Target Particle Excitation • 7 θ-angle regions • 3 from target particle detection (θ≤50°) • 4 from beam particle detection (θ>50°)

  20. 8pi & Tigress, Hackman, Gamma08, RIKEN φ-Dependency for Mixing Ratios • 48Ti γ ray excitation yields fit static moment of 2+ level fit • Shows φ information can be used to find mixing ratio signs of beam particles

  21. 8pi & Tigress, Hackman, Gamma08, RIKEN Mixing Ratio Signs • δ sign depends on relative phases of M1 and E2 components • φ distribution from both signs tested • 21Ne positive χr2=1.55, negative χr2=1.30 • 21Na positive χr2=1.44, negative χr2=1.56 • F-tests quantify the probability of obtaining this result with repeated experiments • 21Ne 70.6%, 21Na 56.5% • Cannot exclude the possibility of the opposite sign

  22. 8pi & Tigress, Hackman, Gamma08, RIKEN 21Ne φ Distribution

  23. 8pi & Tigress, Hackman, Gamma08, RIKEN B(E2) Uncertainties • A number of contributions to the uncertainties of the B(E2) values had to be considered • Statistical error, initial beam energy, target thickness, matrix element values in GOSIA • Resulted in B(E2) uncertainties • 6.2% for 21Ne • 7.2% for 21Na • Uncertainties dominated by statistics and target thickness uncertainty (±20%)

  24. 8pi & Tigress, Hackman, Gamma08, RIKEN Results & Comparison to Priors B(E2)↑ values in W.u. for 3/2+g.s. → 5/2+ • 21Ne • δ = (-)0.0767±0.0025 • Previous: -0.074±0.004 [1] • 21Na • δ = (+)0.0832±0.0030 • Previous: +0.05±0.02 [1] [1] R.B. Firestone, Nuclear Data Sheets 103 (2004) 269, with NNDC Oct. 10, 2006 erratum. [2] J.N. Orce, shell model calculation.

  25. 8pi & Tigress, Hackman, Gamma08, RIKEN Very Preliminary Conclusions • Difference in structure between 21Ne and 21Na greater than is reproduced using the standard effective charges • Increasing ep-en moves in the right direction • Are ep=1.5e, en=0.5e inappropriate for this mass region? • Further theoretical investigation needed Work of Michael Schumaker, University of Guelph, et al. Draft

  26. 8pi & Tigress, Hackman, Gamma08, RIKEN Final Thoughts • 8pi pushing limits of precision for beta decay • Wide campaign of superallowed Fermi emitters • Other published results: 11Li, 32Na, 178m2Hf, 174Tm … • TIGRESS operational • First experiment – successful measurement, intriguing results • Data taken with 21Na and 11Be beams as well • Time for high-precision RIB physics • Revisit some “reliable” standards?

  27. Thank you to organizers! 8pi & Tigress, Hackman, Gamma08, RIKEN 4004 Wesbrook Mall Vancouver, B.C. Canada V6T 2A3 Tel: 604 222-1047 Fax: 604 222-1074 www.triumf.cagamma.triumf.ca

  28. 8pi & Tigress, Hackman, Gamma08, RIKEN DESCANT • Build a partial spherical shell to cover forward lampshade • 70 ~hexagonal detectors in 5 rings • 4 shapes for close-pack tiling • green has two chiralities • Maximum angle 65.5 • 93% of available solid angle – 1.08p sr • Front face distance 50 cm • Detectors 15 cm thick • Light detected by Photonis 3 tubes • Pulses digitized by TIG-4G modules • 4 channels, 12-bit @ 1GHz • 18 modules in 2 VME64X crates • DESCANT – DEuterated SCintillator Array for Neutron Tagging $1.8M project funded by Canadian Foundation for Innovation, Ontario Innovation Trust, and TRIUMF

  29. 8pi & Tigress, Hackman, Gamma08, RIKEN SHARC Silicon Barrel • Solidworks concept (Mines) • Technical drawings (York/Manchester) • Review & Integration within TIGRESS (York/TRIUMF) - in progress • Construction (LSU)

  30. In superallowed Fermiβ decays, Probability of Electron Capture Measured half-life Superallowed Branching Ratio 8pi & Tigress, Hackman, Gamma08, RIKEN we can calculate the transition matrix element without knowing any details of the nuclear wave function. Lb= 0 Sb= 0 Transitions between isobaric analogue states Constants 2 2 For T=1 isobaric analogues: Statistical rate function Partial half-life Nucleus dependent corrections Weak vector coupling constant Nucleus independent correction

  31. 8pi & Tigress, Hackman, Gamma08, RIKEN One method of identifying contaminants:Use (way too) thick of a target • 110Pd(29Na,29Na*) @ 2.41 MeV/u • Ib(29Na) ~ 400-800 pps on Coulex target • (NA/A)t ~ 2.94 mg/cm2 • Brick • dE/dX of Al vs Na adequate to resolve them in Si!

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