Decay of the high-spin isomer in Re-160: Changing single-particle structure beyond the proton drip line

Abstract

WOS: 000286708700015 ; A new high-spin isomeric state (t(1/2) = 2.8 +/- 0.1 mu s) in Re-160 has been identified. This high-spin isomer is unique in that it only decays by gamma-decay and not by proton or alpha-particle emission as is the case in every other proton emitter between Z = 64 and 80. Shell model calculations indicate how the convergence of the h(9/2) and f(7/2) neutron levels in this region could open up a gamma-decay path from the high-spin isomer to the low-spin ground state of 160Re. providing a natural explanation for this anomalous absence of charged-particle emission. The consequences of these observations for future searches for proton emission from even more exotic nuclei and in-beam spectroscopic studies are considered. (C) 2010 Elsevier B.V. All rights reserved. ; UK Science and Technology Facilities Council; Swedish Natural Science Research Council; Academy of Finland [44875, 209430, 111965]; European Union [RII3-CT-2004-506065, HPMT-CT-2001-00250]; Science and Technology Facilities Council [ST/G008671/1, ST/J000108/1, EP/C015371/1, ST/J000094/1, EP/C015266/1, ST/G008620/1, ST/F012039/1] ; The authors thank the technical staff at the University of Jyvaskyla for their excellent support, Paul Morrall for making the targets and Witek Nazarewicz for stimulating discussions. This work was supported by the UK Science and Technology Facilities Council; the Swedish Natural Science Research Council; the Academy of Finland through the Finnish Centre of Excellence Programme (project 44875 Nuclear and Condensed Matter Physics Programme at JYFL) and support for C.S. (contract 209430) and P.T.G. (contract 111965); the European Union Sixth Framework contract EURONS (RII3-CT-2004-506065) and the European Union Marie Curie Programme (contract HPMT-CT-2001-00250).