title: Ground-state proton decay of 69Br and implications for the 68Se astrophysical rapid proton-capture process waiting point.
abstract: We report on the first direct measurement of the proton separation energy for the proton-unbound nucleus (69)Br. Bypassing the (68)Se waiting point in the rp process is directly related to the 2p-capture rate through (69)Br, which depends exponentially on the proton separation energy. We find a proton separation energy for (69)Br of Sp((69)Br )= -785(-40)(+34) keV; this is less bound compared to previous predictions which have relied on uncertain theoretical calculations. The influence of the extracted proton separation energy on the rp process occurring in type I x-ray bursts is examined within the context of a one-zone burst model.
authors.affiliation: National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824, USA. amrogers@phy.anl.gov
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