Mass Measurements of Proton-Rich Isotopes Between Mo and Pd for $rp$- and $\nu p$-process Models

The reaction paths of two proposed nucleosynthetic processes on the proton-rich side of stability, the $rp$ and $\nu p$~processes, pass through a series of nuclides between Mo and Pd whose masses have long gone unmeasured. Measurements of these masses would provide the more precise proton-separation energies, $S_p$, needed to properly model the paths and final abundances of these two astrophysical processes. These $S_p$ values are of particular interest to the $\nu p$ process as it is a process which could resolve the long- standing underproduction of light $p$-nuclei such as $^{92}$Mo and $^{94}$Mo. Mass measurements of 14 proton-rich nuclides between Mo and Pd have been performed with the Canadian Penning trap mass spectrometer. These measurements have significantly reduced uncertainties in the associated $S_{p}$ values by up to factors of 60. These results and their astrophysical implications will be discussed. This work supported by: NSERC, Canada and the U.S. DOE, Nuclear Physics Division, Contract Nos. DE-AC02-06CH11357 and DE-FG02- 91ER-40609.