Nuclear properties in an astrophysical environment

Abstract

The process of nucleosynthesis is one of the most interesting nuclear processes in modern astrophysics. The nucleosynthesis is present in different scenarios such as The Big Bang, supernovae explosion, or stellar nucleosynthesis. These processes are important from a thermodynamic perspective. This approach is based on the study of the nuclei at certain conditions of temperature, entropy and chemical potential. With the proper relation of these concepts under certain conditions of interest, one can study the dynamics for certain astrophysical phenomena of interest. Apart from this, the concept of nuclear temperature is of interest for heavy ion collisions and in general for processes where nuclear excitations become important.

In this project we focused on the study, and on the understanding of the nucleus under certain thermodynamic conditions. This was carried out making a review of the most basic properties of the nucleus for the present work, these were summarized in Chapter 1. The basic concepts of Binding Energy, Nuclear Potentials and Nuclear deformation are explained. In Chapter 2, we step forward to study the basic definitions of statistical mechanics applied to the nucleus starting from the Fermi Gas formalism towards the definition of level density and its use in the nuclear matter equation of state. Once the basic concepts are defined, in Chapter 3 we focus on the application of these concepts in the definition of Hot Nuclei and along with its behavior in Supernovae. After forming the background for studying hot nuclei, calculations are performed to obtain the temperature dependence of the parameters in the Bethe-Weizs¨acker semiempirical mass formula leading to temperature dependent binding energies of nuclei. These calculations are done by performing fits to an extensive data on the excited states of 286 nuclei. Such a study was last performed about 25 years ago and the parameters of that study are still being used for different studies. The present work provides an updated version of the same with more extensive data. Modifications of the mass formula based on the inclusion of deformation and shell effects can be performed in future.