Sensitivity of stellar electron-capture rates to parent neutron number: A case study on a continuous chain of twenty Vanadium isotopes

TL;DR

This study compares theoretical models and experimental data of Gamow-Teller strength distributions in Vanadium isotopes to analyze how electron-capture rates vary with neutron number, with implications for astrophysical processes.

Contribution

It provides the first systematic examination of electron-capture rate sensitivities across a chain of Vanadium isotopes using multiple theoretical approaches and experimental data.

Findings

EC rates vary significantly with neutron number.

Theoretical models show good agreement with experimental data.

Rate sensitivities depend on stellar density and temperature.

Abstract

Gamow-Teller (GT) strength distributions (B(GT)) in electron-capture (EC) daughters stemming from the parent ground state are computed with the shell-model in the full pf-shell space, with quasi-particle random-phase approximation (QRPA) in the formalism of Krumlinde and M\"oller and with an Approximate Method (AM) for assigning an effective B(GT). These are compared to data available from decay and charge-exchange (CE) experiments across titanium isotopes in the pf-shell from A=43 to A=62, the largest set available for any chain of isotopes in the pf-shell. The present study is the first to examine B(GT) and the associated EC rates across a particular chain of isotopes with the purpose of examining rate sensitivities as neutron number increases. EC rates are also computed for a wide variety of stellar electron densities and temperatures providing concise estimates of the relative size of rate sensitivities for particular astrophysical scenarios. This work underscores the astrophysical motivation for CE experiments in inverse kinematics for nuclei away from stability at the luminosities of future Radioactive Ion Beam Facilities.