Search

β -decay is one of the key factors for understanding the r-process and evolution of massive stars. The Gamow–Teller (GT) transitions drive the β -decay process. We employ the proton–neutron quasiparticle random phase approximation (pn-QRPA) model to calculate terrestrial and stellar β -decay rates for 50 top-ranked nuclei possessing astrophysical significance according to a recent survey. The model parameters of the pn-QRPA model affect the predicted results of β -decay. The current study investigates the effect of nucleon–nucleon pairing gaps on charge-changing transitions and the associated β decay rates. Three different values of pairing gaps, namely TF, 3TF, and 5TF, were used in our investigation. It was concluded that both GT strength distributions and half-lives are sensitive to pairing gap values. The 3TF pairing gap scheme, in our chosen nuclear model, resulted in the best prediction with around 80% of the calculated half-lives within a factor 10 of the measured ones. The 3TF pairing scheme also led to the calculation of the biggest β -decay rates in stellar matter. [ABSTRACT FROM AUTHOR]

β-decay is one of the key factors for understanding the r-process and evolution of massive stars. The Gamow–Teller (GT) transitions drive the β-decay process. We employ the proton–neutron quasiparticle random phase approximation (pn-QRPA) model to calculate terrestrial and stellar β-decay rates for 50 top-ranked nuclei possessing astrophysical significance according to a recent survey. The model parameters of the pn-QRPA model affect the predicted results of β-decay. The current study investigates the effect of nucleon–nucleon pairing gaps on charge-changing transitions and the associated β decay rates. Three different values of pairing gaps, namely TF, 3TF, and 5TF, were used in our investigation. It was concluded that both GT strength distributions and half-lives are sensitive to pairing gap values. The 3TF pairing gap scheme, in our chosen nuclear model, resulted in the best prediction with around 80% of the calculated half-lives within a factor 10 of the measured ones. The 3TF pairing scheme also led to the calculation of the biggest β-decay rates in stellar matter.

Recent studies (Boillos and Sarriguren, Phys. Rev. C 3(91):034311, 2015; Moreno et al., Phys. Rev. C, 73(5):054302, 2006) predicted the sensitivity of the Gamow-Teller (GT) strength distributions on nuclear deformation in neutron-deficient Hg isotopes. Motivated by this work we investigate nuclear ground state properties and GT strength distributions for neutron-deficient Hg isotopes ( 177 -- 193 Hg). The nuclear deformation ( β 2 ) values were calculated using the Relativistic Mean Field (RMF) model. The RMF approach with different density-dependent interactions, namely, DD-ME2 (meson-exchange) and DD-PC1 (point-coupling), was used to compute nuclear shape parameters. The computed deformation values were later used within the framework of deformed proton-neutron quasi-random phase approximations (pn-QRPA) model, with a separable interaction, to calculate the allowed GT strength distributions for these Hg isotopes. Our calculations validate the findings of Boillos and Sarriguren (Phys. Rev. C 3(91):034311, 2015) and confirmed the effect of deformation on GT strength distributions. Our study may further provide a complementary signature for nuclear shape isomers. Noticeable differences are highlighted between the current and previous calculations. The calculation of Boillos and Sarriguren (Phys. Rev. C 3(91):034311, 2015) shows that 174 -- 182 Hg posses prolate and 184 -- 196 Hg have oblate shapes. Our calculation, on the other hand, predicts prolate shape for 177 -- 185 Hg and oblate shape for 186 -- 193 Hg isotopes. We finally analyze the effect of deformation on the calculated T 1 / 2 for the selected Hg isotopes. Our half-life calculations do not validate the findings of Moreno et al. (Phys. Rev. C 73(5):054302, 2006) that T 1 / 2 values are not good enough observables to study deformation effects. [ABSTRACT FROM AUTHOR]