Gamow-Teller strength distributions and stellar weak-interaction rates for $^{76}$Ge and $^{82}$Se using the deformed pn-QRPA model

TL;DR

This paper uses a deformed pn-QRPA model to calculate Gamow-Teller strength distributions and weak-interaction rates for $^{76}$Ge and $^{82}$Se, relevant for supernovae, and compares results with experimental data.

Contribution

It introduces a detailed deformed pn-QRPA approach including pairing and ground state correlations for accurate weak-interaction rate calculations.

Findings

Calculated Gamow-Teller strength distributions match experimental data.

Positron capture rates dominate at high stellar temperatures.

Energy rates of $eta$-delayed neutrons were also computed.

Abstract

We calculate Gamow-Teller strength distributions for $\beta \beta$-decay nuclei $^{76}$Ge and $^{82}$Se using the deformed pn-QRPA model. We use a deformed Nilsson basis and consider pairing correlations within the deformed BCS theory. Ground state correlations and two-particle and two-hole mixing states were included in our pn-QRPA model. Our calculated strength distributions were compared with experimental data and previous calculation. The total Gamow-Teller strength and centroid placement calculated in our model compares well with the measured value. We calculate $\beta$-decay and positron capture rates on $^{76}$Ge and $^{82}$Se in supernovae environments and compare them to those obtained from experimental data and previous calculation. Our study shows that positron capture rates command the total weak rates at high stellar temperatures. We also calculate energy rates of $\beta$-delayed neutrons and their emission probabilities.