Spin-isospin transitions in chromium isotopes within the quasiparticle random phase approximation

Abstract

Beta decay and electron capture on isotopes of chromium are advocated to play a key role in the stellar evolution process. In this paper we endeavor to study charge-changing transitions for 24 isotopes of chromium ( 42−65 Cr). These include neutron-rich and neutron-deficient isotopes of chromium. Three different models from the QRPA genre, namely the pn-QRPA, the Pyatov method (PM) and the Schematic model (SM), were selected to calculate and study the Gamow-Teller (GT) transitions in chromium isotopes. The SM was employed separately in the particle-particle (pp) and pp + particle-hole (ph) channels. To study the effect of deformation, the SM was first used assuming the nuclei to be spherical and later to be deformed. The PM was used both in pp and pp + ph channels but only for the case of spherical nuclei. The pn-QRPA calculation was done by considering both pp and ph forces and taking deformation of nucleus into consideration. A recent study proved this version of pn-QRPA to be the best for calculation of GT strength distributions amongst the QRPA models. The pn-QRPA model calculated GT distributions had low-lying centroids and small widths as compared to other QRPA models. Our calculation results were also compared with other theoretical models and measurements wherever ✩ This template can be used for all publications in Advances in Space Research.available. Our results are in decent agreement with previous measurements and shell model calculations.

$\beta $-decay Properties of Waiting-point Nuclei for Astrophysical Applications

“…We compare our calculation with several previous pioneering calculations [20,21,22,30,31] as well as against experimental data [28]. We multiplied results of pn-QRPA calculated strength by a quenching factor of f 2 q = (0.55) 2 [32] in order to compare them with experimental data and prior calculations, and to later use them in astrophysical reaction rates.…”

First-forbidden transitions and stellarβ-decay rates of Zn and Ge isotopes

“…For U1F transitions authors in [25] employed a much tighter quenching factor of 0.5. In order to compare our results with experimental data and previous calculations, we introduced a quenching factor of 0.6 [26,27,28] in both pn-QRPA(WS) and pn-QRPA(N) models as also used in shell model calculations. In future we would like to explore the effect of using different quenching factor for allowed, FF and U1F transitions in pn-QRPA(WS) and pn-QRPA(N) models.…”

Gamow-Teller strength distributions and neutrino energy loss rates due to chromium isotopes in stellar matter

“…The idea was to find out the best pn-QRPA model to perform the stellar weak interaction rates with the respective model parameters. It was concluded in (Cakmak et al 2015) that the current pn-QRPA model was indeed the best model that reproduced not only the available experimental data but had the best predictive power for estimate of weak rates of nuclei far away from line of stability. In this paper we use the same model (with same model parameters) to calculate (anti)neutrino cooling rates due to isotopes of chromium.…”

“…The QRPA takes into account pairing correlations albeit in a non-perturbative way. Earlier a similar study for calculation of GT transitions for key chromium isotopes, using different pn-QRPA models, was performed (Cakmak et al 2015). The idea was to find out the best pn-QRPA model to perform the stellar weak interaction rates with the respective model parameters.…”