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Decay studies in Exotic, Neutron-Rich A~200 Nuclei

Decay studies in Exotic, Neutron-Rich A~200 Nuclei. Steven Steer for the Stopped Beam RISING Collaboration Dept. of Physics, University of Surrey Guildford, Surrey, GU2 7XH, UK s.steer@surrey.ac.uk. The RISING ‘Stopped Beam’ Campaign. Passive Stopper : Isomer (gamma) decay Measurements.

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Decay studies in Exotic, Neutron-Rich A~200 Nuclei

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  1. Decay studies in Exotic, Neutron-Rich A~200 Nuclei Steven Steer for the Stopped Beam RISING Collaboration Dept. of Physics, University of Surrey Guildford, Surrey, GU2 7XH, UK s.steer@surrey.ac.uk

  2. The RISING ‘Stopped Beam’ Campaign Passive Stopper : Isomer (gamma) decay Measurements Active Stopper : Isomer internal conversion electron and beta-decay measurements Today three experiments will be discussed. All three experiments focus on: Neutron-Rich, Z<82, A~200 nuclei Fragmentation of 208Pb and 238U This work is performed at GSI using the Fragment Separator and the RISING gamma-ray spectrometer

  3. Overview of Experiment #1 Z = 82 >> >> N = 126 Fragmentation of E/A = 1GeV 208Pb with passive stopper (isomer gamma decay) The first experimental information on excited states in 15 nuclides.

  4. Previous Kowledge at N=126, Z<82 Z=80 Z=81 PRL B. Fornal et. al. (2001)

  5. Progress at N=126 : Z=77, 203Ir and Z=78 204Pt 203Ir Data from 8,000 203Irnuclei 204Pt

  6. Shell-model calculations (M.Górska, H.Grawe, H. Maier, A.Brown) • and (d):TBME from L.Rydstrom et al, NPA512(1990)217 (based on Kuo-Brown interaction) • (b) and (c): three TBMEs modified • Δ(d3/2 h11/2; d3/2 h11/2)7- = +135 keV • Δ(s1/2 d5/2; s1/2 d5/2)2+,3+ =+250 keV (monopole only) • Δ(d3/2 h11/2; s1/2 h11/2)6- changed to +0.160 MeV (fit for B(E2) • Good description of energies and B(EL)s S.Steer et al., submitted to rapid Communications

  7. Progress at N=126 : Z=79, 205Au Isomer gamma decay B(E2; 34) = 1.1 W.u. B(E3; 962) = 0.4 W.u. Isomer conversion electrons Electron conversion data: Zs. Podolyák et al., submitted to Phys. Lett. B

  8. N=126, Z<82, odd-Z decay schemes 203Ir Z=77 Z=81 Z=79 • TBME from L.Rydstrom et al, NPA512(1990)217 (based on Kuo-Brown) • Modified (a) to get better desription of 204Pt

  9. Experiment #2: beta decay studies 188Ta → 188W 190Ta → 190W 192Ta → 192W N. Alkhomashi, P.H. Regan et al.,

  10. N=126 towards r-process path N=126 H. Grawe, K. Langanke, G. Martinez-Pinedo, Rep.Progr.Phys.70 (2007)1525. Larger differences at N=126 (lack of experimental data) N=82

  11. Experiment #3: N>126 208Hg (Z=80;N=128) preliminary T1/2 ~ 10 - 100 ns N. Aldahan, Zs. Podolyak et al.

  12. The RISING Collaborators Named collaborators are for the 204Pt research

  13. In Summary Analysis beginning: Beta- and isomer-decay studies 208Hg Experiment #1 27 isomers discovered 48 measured in total Experiment #3 Analysis in progress: Beta-decay studies 188,190,192W Experiment #2

  14. N=122 isotones πh11/2-1d3/2 πh11/2-1s1/2 From RISING S.Yates et al., PRC37 (1988)1889.

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