Decay studies in Exotic, NeutronRich A200 Nuclei

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Decay studies in Exotic, Neutron-Rich A200 Nuclei
Steven Steer for the Stopped Beam RISING
Collaboration Dept. of Physics, University of
Surrey Guildford, Surrey, GU2 7XH,
UK s.steer_at_surrey.ac.uk
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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, Zlt82,
A200 nuclei
Fragmentation of 208Pb and 238U
This work is performed at GSI using the Fragment
Separator and the RISING gamma-ray spectrometer
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Overview of Experiment 1
Z 82 gtgt
gtgt
N 126
Fragmentation of E/A 1GeV 208Pb with passive
stopper (isomer gamma decay)
The first experimental information on excited
states in 15 nuclides.
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Previous Kowledge at N126, Zlt82
Z80
Z81
PRL B. Fornal et. al. (2001)
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Progress at N126 Z77, 203Ir and Z78 204Pt
203Ir
Data from 8,000 203Ir nuclei
204Pt
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• 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
• ?(d3/2 h11/2 d3/2 h11/2)7-  135 keV
• ?(s1/2 d5/2 s1/2 d5/2)2,3 250 keV (monopole
  only)
• ?(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
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Progress at N126 Z79, 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
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N126, Zlt82, odd-Z decay schemes
203Ir
Z77
Z81
Z79

• TBME from L.Rydstrom et al, NPA512(1990)217
  (based on Kuo-Brown)
• Modified (a) to get better desription of 204Pt

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Experiment 2 beta decay studies
188Ta ? 188W
190Ta ? 190W
192Ta ? 192W
N. Alkhomashi, P.H. Regan et al.,
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N126 towards r-process path
N126
H. Grawe, K. Langanke, G. Martinez-Pinedo,
Rep.Progr.Phys.70 (2007)1525.
Larger differences at N126 (lack of experimental
data)
N82
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Experiment 3 Ngt126
208Hg (Z80N128)
preliminary
T1/2 10 - 100 ns
N. Aldahan, Zs. Podolyak et al.
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The RISING Collaborators
Named collaborators are for the 204Pt research
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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
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N122 isotones
ph11/2-1d3/2
ph11/2-1s1/2
From RISING
S.Yates et al., PRC37 (1988)1889.