Determination of the proton separation energy of Rh93 from mass measurements

The proposed νp process, which occurs in the early time proton-rich neutrino winds of core-collapse supernovae, has the potential to resolve the long-standing uncertainty in the production of the light p-nuclei Mo92 and Mo94. A recent study incorporating this νp process has indicated that the proton separation energy Sp of Rh93 is especially important in determining the relative production of these two isotopes. To reproduce the observed solar Mo92/Mo94 abundance ratio of 1.57 a Sp value for Rh93 of 1.64±0.1 MeV is required. The previously unknown masses of Ru92 and Rh93 have been measured with the Canadian Penning Trap mass spectrometer resulting in an experimental value for Sp(Rh93) of 2.007±0.009 MeV. This implies that with our current understanding of the conditions in core-collapse supernova explosions the νp process is not solely responsible for the observed solar Mo92/Mo94 abundance ratio.