Mass measurements of isotopes of Nb, Mo, Tc, Ru, and Rh along the νp- and rp-process paths using the Canadian Penning trap mass spectrometer

The reaction paths of two proposed nucleosynthetic processes on the proton-rich side of stability, the rp and νp processes, pass through a region of isotopes between Mo and Pd where masses had long gone unmeasured. Precise knowledge of the paths and final abundances of these two processes has been limited by the corresponding lack of precision in the proton-separation energies S_p when derived from extrapolated masses. The masses of 18 neutron-deficient isotopes of Nb, Mo, Tc, Ru, and Rh have been measured using the Canadian Penning trap mass spectrometer. Three of the masses presented, 90Mo, 91Mo, and 93Tc, provide the first direct measurement of the masses of these nuclides, and the others provide confirmation of recent measurements using other Penning traps. Included in this work is a measurement of the mass of 87Mo, which differs by 3.7σ from the mass presented in the 2003 Atomic Mass Evaluation. This leads to a change in the S_p value of 88Tc which reduces the suppression of flow of the νp-process path through 87Mo(p,γ)88Tc reported following the mass measurement of 88Tc. This in turn affects the resulting νp-process abundances.