Measurement of key resonance states for the P 30 ( p , γ ) S 31 reaction rate, and the production of intermediate-mass elements in nova explosions

摘要

We report the first experimental constraints on spectroscopic factors and strengths of key resonances in the P 30 ( p , γ ) S 31 reaction critical for determining the production of intermediate-mass elements up to Ca in nova ejecta. The P 30 ( d , n ) S 31 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 indicate the dominance of a single 3 / 2 ? resonance state at 196 keV in the region of nova burning T ≈ 0.10 – 0.17 ? GK , well within the region of interest for nova nucleosynthesis. Hydrodynamic simulations of nova explosions have been performed to demonstrate the effect on the composition of nova ejecta.