Direct Mass Measurements of Short-Lived A=2Z-1 Nuclides 63Ge, 65As, 67Se, and 71Kr and Their Impact on Nucleosynthesis in the rp Process

Mass excesses of short-lived A = 2Z - 1 nuclei Ge-63, As-65, Se-67, and Kr-71 have been directly measured to be -46 921(37), -46 937(85), -46 580(67), and -46 320(141) keV, respectively. The deduced proton separation energy of -90(85) keV for As-65 shows that this nucleus is only slightly proton unbound. X-ray burst model calculations with the new mass excess of As-65 suggest that the majority of the reaction flow passes through Ge-64 via proton capture, indicating that Ge-64 is not a significant rp-process waiting point.