Studies on Astrophysical Nuclides Far From Stability with Numerical Simulations and Systematics

Abstract

Explosive events in our universe provide an environment where rare nucleosynthesis events can occur. Understanding the mechanisms and processes during these events is integral to understanding the relative abundances of the elements in our universe. The rapid neutron capture process or r-process is thought to be responsible for producing approximately half of the heavy elements in our universe. A critical input in the calculation of r-process nucleosynthesis is the beta-delayed neutron (B DN) emission probability, Pn. However theoretical calcuations of Pn have not been successful in reproducing experimental values. A semi-empirical formula using systematics can be adopted, which can give an approximate Pn value for unmeasured precursors. To complete this, we carried out a comprehensive evaluation of Pn and half life,T1=2 values from literature, which we present in this work in a table of recommended values for the range Z=30-40,49,50. Two methods of identifying systematics in neutron emission probability Pn (McCutchan et al. 2012),(Kratz,Herrmann, 1988) are compared using the evaluated values, wherein the McCutchan et al. method was signifi cantly more accurate than the Kratz-Herrmann method, and especially so in the lower Q regions. In this work we also explore classical novae and present a sensitivity study on classical nova nucleosynthesis endpoint nuclei. The reaction rates of 36Ar,37Ar and 40K were of particular interest as they showed the largest impact on the fi nal abundances.