The Statistical Properties of 92Mo and Implications for the p-process

Abstract

A challenging part of the question of how elements heavier than iron are created in extreme, astro-physical environments is the creation of p-isotopes. The lack of needed nuclear data presents an obstacle in nailing down the precise site and astrophysical conditions for the production of these isotopes. The p-isotope 92Mo represents one of the most severe cases of underproduction. The main destruction mechanism of this isotope in the standard description of the p-process is through the 92Mo(γ, p)91Nb reaction. Measurements on the nuclear level density and γ strength function of 92Mo have been carried out at the Oslo Cyclotron Laboratory. TALYS cross section and reaction rate calculations using the experimental results as input are presented, providing constraints on the 91Nb(p, γ)92Mo (and consequently the inverse) reaction rate. Further, the reaction rates extracted in this work were used in network calculations for the scenario of a p-process taking place in a type II supernova explosion as the shock front passes through the O-Ne layer of a 25 solar mass star. We conclude that there is no salvation in the nuclear input alone in the 92Mo underproduction problem, strengthening previous conclusions pointing towards more exotic astrophysical scenarios. Show more