Decay Spectroscopy with EURICA in the region of 100 Sn Daniel Lubos for the EURICA RIBF09 collaboration Technische Universität München Jul 09, 2015 @ Science Day of RA G Excellence Cluster Origin and Structure of the Universe
Contents Introduction Facility & Detectors Lifetimes The β-endpoint-energy Further Nuclei: 94 Ag Discussion Daniel Lubos, TUM 2
Introduction Why we need β-decay spectroscopy The region around 100 Sn β-decay systematics nuclear structure accurate lifetime rp-process proton dripline transition strength B Experiment Lifetime Q β -value A 0 A 0 exp(-λt) t è B GT Source: T. Faestermann et al., Prog. Part. Nucl. Phys. 69 (2013) 85 Daniel Lubos, TUM 3
Shell Model & β-decay Super-allowed β-decay Selection Rules: Fermi Decay è + ΔT = 0, ΔI = 0 Gamow Teller Decay è + ΔT = 0,±1, ΔI = 0,1 Source: A. Stolz, PhD-thesis TUM (2001) Daniel Lubos, TUM 4
Facility & Detectors The BigRIPS Facility @ RIKEN Nishina Center, RIBF Primary Beams @ RIBF Beam Intensity / pna Nucleus achieved expected 2011 48 Ca 230 200 86 Kr 30 30 124,136 Xe 38 (~36) 10 238 U 0.8 5 Source: RIKEN Nishina Center 5
World s first ring cyclotron with superconducting sector magnets Facility & Detectors K-value 2500 MeV, 3.8 T, 235 MJ The BigRIPS Facility @ RIKEN Nishina Center, RIBF 8300 t 3 Modes - Fixed beam energy (350 MeV/u) (RILAC, RRC, frc, IRC, SRC) - Variable beam energy (115 MeV/u) (RILAC, RRC, IRC, SRC) - Polarized Deuteron Beam (880 MeV) (AVF, RRC, SRC) Projectile Fragmentation In-flight fission of U-238 1 st Beam: Dec 28, 2006 1 st RI Beam: Mar 15, 2007 Source: RIKEN Nishina Center 6
Source: RIKEN Nishina Center Facility & Detectors The BigRIPS Facility @ RIKEN Nishina Center, RIBF EURICA Separation: Bρ ΔE Bρ ΔE Bρ Identification: Bρ ΔE TOF Daniel Lubos, TUM 7
Facility & Detectors The EURICA Gamma-ray Detector Cluster EUROBALL as used in RISING @ GSI 12 clusters of 7 HPGe Crystals each 3 clusters with 6 LaBr Crystals each Energy Resolution ~ 2 kev Timing Resolution ~ 25 ns Courtesy by G. Lorusso, S. Nishimura Operated at 4 KV Daniel Lubos, TUM 8
Facility & Detectors The EURICA Gamma-ray Detector Cluster WAS3ABI Detector EURICA Clusters Daniel Lubos, TUM Experimental Area 9
Facility & Detectors The WAS 3 ABI Silicion Detector Array Decay (green) 10 x 1 mm Implantation (red) 3 x 1 mm Area: 60 mm x 40 mm Segmentation: DSSD 60 strips X 40 strips Beam tracking (purple) SSSD 7 strips 1 x 0.3 mm Width: 1 mm (compare: e - mean free path: 1 mm) 3 Double-Sided Silicon Strip Detectors (DSSD) 10 Single-Sided Silicon Strip Detectors (SSSD) TOTAL: 380 Channels Daniel Lubos, TUM 10
Facility & Detectors New Isotope Search - Finalized Proton Number Z 89,90 Pd 98 Sn 96 In 94 Cd 92 Ag 99 Sn Smallest log(ft) value in the nuclear chart log(ft) = 2.62 +0.11-0.13 B GT = 9.1 +2.6-3.0 100 Sn 2525 After decay correlations 98 Sn 0 cts 96 In 1 cts 94 Cd 3 cts 92 Ag 1 cts 90 Pd 1 cts 89 Pd 0 cts Mass A / Charge Q Daniel Lubos, TUM 11
Results Lifetime of 100 Sn Counts 80 t 1/2, This Exp. = 1.17 +0.14-0.11 s 100 Sn 70 t 1/2, Hinke = 1.16 ± 0.20 s 60 50 40 Total Spectrum Parent Daughter Background 30 20 10 This Exp. C. Hinke (2012)[6] 6 10 0 100 200 300 400 500 600 700 800 900 1000 Time after implantation / 10 ns Daniel Lubos, TUM 12
Results Background reduction by event selection Time spectrum of 100 Sn β-decay/ 10 ns Here: Event selection by gate on γ-emission in daughter nucleus 98 In 1s 259 cts vs. 1889 implantations Daniel Lubos, TUM
Results β-endpoint-energy Second part regarding the determination of B GT Distinguish Implantation events Decay events Light particle events è Event tracker to judge each event (spatial correlation, time correlation, energy discrimination, pattern analysis) MAX empty MULT Gap è Clean (background reduced) spectrum in order to determine Q β -value Daniel Lubos, TUM 14 T
Results Particle Discrimination Event Tracker Decay Event Beam direction Z Light Particle Event Noise 10 9 8 SSD Stack 7 6 5 SSSD: beta index 3, histcnt 2 1400 1200 1000 800 Yà Zà (27,17) (26,17) 4 3 2 1 0 0 1 2 3 4 5 6 7 2 DSSD 3, beta_index 2, histcnt 152580368 40 35 30 DSSD C 25 20 15 10 5 0 0 10 20 30 40 50 60 1 DSSD 3, beta_index 2, histcnt 1024 40 35 30 DSSD B 25 20 15 10 5 0 0 10 20 30 40 50 60 0 DSSD 3, beta_index 2, histcnt 152580368 40 35 30 DSSD A 25 20 15 10 5 Zà Yà 600 400 200 0 1400 1200 1000 800 600 400 200 0 1400 1200 1000 800 600 400 200 0 1400 1200 1000 800 600 400 200 Xà 0 Xà 0 10 20 30 40 50 60 0 Daniel Lubos, TUM 15
Results First β-endpoint-energy Spectrum Number of Events 22 20 18 16 14 12 10 8 6 4 2 0 Integral: 412 Cts Entries 412 à C. Hinke (2012) [6] ~ 80 Cts Q β = 3.29 ± 0.20 MeV 500 1000 1500 2000 2500 3000 3500 4000 4500 Summed Electron Energy Deposit / kev Daniel Lubos, TUM 16
Results First β-endpoint-energy Spectrum Number of Events 22 20 18 16 14 12 10 8 6 4 2 0 Integral: 412 Cts Entries 412 SSD Stack DSSD C DSSD B 500 1000 1500 2000 2500 3000 3500 4000 4500 Summed Electron Energy Deposit / kev Daniel Lubos, TUM 17
Results Beyond the N = Z line Lifetimes of N = Z 1 nuclei using MLH method Counts / 5 ms 8 7 6 Total Spectrum Parent Daughter Background 99 Sn 5 4 3 2 1 0 10 0 5 10 15 20 25 30 35 40 45 50 Daniel Lubos, TUM Time after implantation [10 ns] 6
Results Beyond the N = Z line Lifetimes of N = Z 1 nuclei using MLH method Counts / 5 ms 8 7 6 Total Spectrum Parent Daughter Background 99 Sn 5 4 3 2 1 0 10 0 5 10 15 20 25 30 35 40 45 50 Daniel Lubos, TUM Time after implantation [10 ns] 6
Further Nuclei: 94 Ag Study of Decay Channels 2p p β βp Occupation Scheme 3ћω π ν 1g 9/2 (10) 2p 1/2 (2) 1f 5/2 (6) 2p 3/2 (4) Decay channels of 94 Ag Level Scheme 6670 kev 0 kev 21 + 0.4 s, ε95.4%, εp 27%, p4.1%, 2p0.5% 0 + 26 ms, ε100%, εp? è no γs 7 + 0.55 s, ε100%, εp 20% 0.0 + X kev 94 Ag 21 + show 2p decay to 92 Rh Highest known spin-isomer [1] I. Mukha et al., Nature 439 (2006) 298 92 Rh
Further Nuclei: 94 Ag Half-life, two parent components 400 350 300 250 f 1/2 s T T 1/2 Time after implantation / 10 ns = 26 ms = 0.5 s T f 1/2 = 26 ms T s 1/2 = 0.51 s 200 150 100 50 0 10 0 50 100 150 200 250 300 6
Further Nuclei: 94 Ag Study of Decay Channels β-region Strip Energies / kev 2p-peak p-region Daniel Lubos, TUM
Further Nuclei: 94 Ag Coincident γ-lines, fast component t < 0.06 s Si-Energy / kev γ-energy / kev
counts Further Nuclei: 94 Ag Coincident γ-lines, slow component 0.1 s < t <1.2 s γ-energy / kev Si-Energy / kev 0.1 s < t <1.2 s Si-Energy / kev γ-energy / kev
Further Nuclei: 94 Ag C oincident γ-lines, slow component 0.1 s < t <1.2 s Si-Energy / kev T 1/2 = 0.57(10)(x) s Time / 10 ns γ-energy / kev
Further Nuclei: 94 Ag Hint for 2p-decay Event-by-event analysis Single γ-energies / kev Hint for 2p decay, consistent with [1] Addback γ-energies / kev [1] Phys. Rev. C 76, 011304(R) (2007)
Further Nuclei 94 Ag Hint for 2p-decay 2p decay: event-by-event analysis Pixel energy / kev time / ms γ-energies crystal / kev 1845 392 98, 365, 599, 313, 601, 173 1885 984 787 787 1885 673 104, 147 104, 147 γ energies cluster addback / kev 98, 964, 313, 601, 173 1845 666 274, 349, 740 274, 349, 740 1865 591 283, 813 1096 1855 538 166, 349 515 1895 213 79, 184 79, 184 1845 483 ---- ---- 1835 810 ---- ----
Further Nuclei: 94 Ag Hint for 2p-decay Study of 2p-decay channels Scenarios of coincident 833 kev and 565 kev lines [1] O. L. Pechenaya, Phys. Rev. C76, 011304(R) (2007) Each ruled out by a confidence level of at least 96% This experiment: concerning 94 Ag statistics are too less for new conclusions. Another dedicated campeign is necessary.
Summary Status of Analysis & Outlook About finalizing 100 Sn analysis (half-lives, Qβ Determined lifetimes of N = Z 1 nuclei Obtained much better statistics Much information about neighboring nuclei and its structure Collaborators @ TRIUMF, Canada are working on the γ-spectroscopy of measured nuclei Great region to study the shell model and dig into β-delayed γ- spectroscopy Daniel Lubos, TUM 29
Collaboration I appreciate work with and support from the EURICA RIBF09 collaboration, the RIKEN Nishina Center, the RIKEN IPA Program and the DFG Excellence Cluster Origin and Structure of the Universe. Collaborators M. Lewitowicz, R. Gernhäuser, R. Krücken, S. Nishimura, H. Sakurai, H. Baba, B. Blank, A. Blazhev, P. Boutachkov, F. Browne, I. Celikovic, P. Doornenbal, T. Faestermann, Y. Fang, G. de France, N. Goel, M. Gorska, S. Ilieva, T. Isobe, A. Jungclaus, G. D. Kim, Y.-K. Kim, I. Kojouharov, M. Kowalska, D. Lubos, N. Kurz, Z. Li, G. Lorusso, K. Moschner, I. Nishizuka, J. Park, Z. Patel, M. M. Rajabali, S. Rice, H. Schaffner, L. Sinclair, P.-A. Söderström, K. Steiger, T. Sumikama, H. Watanabe, Z. Wang, J. Wu, and Z. Y. Xu Institutions Physik Department E12, Technische Universität München; RIKEN Nishina Center; TRIUMF; GANIL; Department of Physics, University of Tokyo; CENBG, Institut für Kernphysik; Universität zu Köln; GSI Darmstadt; School of Comp., Eng. and Maths., Brighton University; Department of Physics, Osaka University; Institut für Kernphysik; TU Darmstadt; IES CSIS; Institute for Basic Science; CERN, School of Physics, Peking University; Department of Physics, Tohoku University; Department of Physics, Surrey University; Department of Physics, University of York; Department of Physics, Beihang University Daniel Lubos, TUM 30
Thank you for listening! References [1] H. Suzuki et al. Nucl. Inst. and Meth. in Physics B 317 (2013) 756 768 [2] I. Celikovic PhD thesis, Université de Caen Basse-Normandie (2014) [3] K. Straub PhD thesis, Technische Universität München (2011) [4] A. Blazhev et al., Phys. Rec. C 69, 064304 (2004) [5] A. Blazhev et al., JoP: Conf. Series 205 (2010) 012035 [6] C. Hinke, Nature 486 (2012) 341 [7] T. Faestermann et al., Prog. Part. Nucl. Phys. 69 (2013) 85 [8] A. Stolz, PhD-thesis TUM (2001) Daniel Lubos, TUM 31