Continuum quasiparticle random phase approximation for astrophysical direct neutron capture reaction of neutron-rich nuclei

TL;DR

This paper develops a theoretical framework combining Hartree-Fock-Bogoliubov and QRPA methods to calculate neutron capture cross sections in neutron-rich nuclei, crucial for understanding nucleosynthesis.

Contribution

It introduces a novel many-body approach to compute direct neutron capture reactions in neutron-rich nuclei using continuum QRPA.

Findings

Numerical example for $^{142}$Sn photo-absorption.

Calculation of neutron capture cross section for $^{141}$Sn.

Application of reciprocity theorem to decompose cross sections.

Abstract

We formulate a many-body theory to calculate the cross section of direct radiative neutron capture reaction by means of the Hartree-Fock-Bogoliubov mean-field model and the continuum quasiparticle random phase approximation (QRPA). A focus is put on very neutron-rich nuclei and low-energy neutron kinetic energy in the range of O(1 keV) - O(1 MeV), relevant for the rapid neutron-capture process of nucleosynthesis. We begin with the photo-absorption cross section and the E1 strength function, then, in order to apply the reciprocity theorem, we decompose the cross section into partial cross sections corresponding to different channels of one- and two-neutron emission decays of photo-excited states. Numerical example is shown for the photo-absorption of $^{142}$Sn and the neutron capture of $^{141}$Sn.