Measurement of key resonance states for the P30(p,γ)S31 reaction rate, and the production of intermediate-mass elements in nova explosions

2017

We report the first experimental constraints on spectroscopic factors and strengths of key resonances in the P30(p,γ)S31 reaction critical for determining the production of intermediate-mass elements up to Ca in nova ejecta. The P30(d,n)S31 reaction was studied in inverse kinematics using the GRETINA γ -ray array to measure the angle-integrated cross-sections of states above the proton threshold. In general, negative-parity states are found to be most strongly produced but the absolute values of spectroscopic factors are typically an order of magnitude lower than predicted by the shell-model calculations employing WBP Hamiltonian for the negative-parity states. The results clearly indicat…