Study of the Effect of Newly Calculated Phase Space Factor on β-Decay Half-Lives

Ovidiu Niţescu,Sabin Stoica,Mihail Mirea,Mavra Ishfaq,Jameel-Un Nabi

doi:10.1155/2019/5783618

Abstract

We present results for β-decay half-lives based on a new recipe for calculation of phase space factors recently introduced. Our study includes fp-shell and heavier nuclei of experimental and astrophysical interests. The investigation of the kinematics of some β-decay half-lives is presented, and new phase space factor values are compared with those obtained with previous theoretical approximations. Accurate calculation of nuclear matrix elements is a prerequisite for reliable computation of β-decay half-lives and is not the subject of this paper. This paper explores if improvements in calculating the β-decay half-lives can be obtained when using a given set of nuclear matrix elements and employing the new values of the phase space factors. Although the largest uncertainty in half-lives computations come from the nuclear matrix elements, introduction of the new values of the phase space factors may improve the comparison with experiment. The new half-lives are systematically larger than previous calculations and may have interesting consequences for calculation of stellar rates.

Highlights

The precise knowledge of the β-decay rates represents an important ingredient for understanding the nuclear structure as well as the astrophysical processes like presupernova evolution of massive stars, nucleosynthesis (s, p, r, rp-) processes, etc. [1,2,3])
In the calculations of this work, the Coulomb field is obtained by considering a nuclear charge distribution obtained within a shell model and a screening effect is introduced by modifying the potential
The newly calculated β-decay half-lives were systematically larger than those given in the previous calculations

Summary

Introduction

The precise knowledge of the β-decay rates represents an important ingredient for understanding the nuclear structure as well as the astrophysical processes like presupernova evolution of massive stars, nucleosynthesis (s-, p-, r-, rp-) processes, etc. [1,2,3]). That is why the calculation of the β-decay half-lives in agreement with experimental results has been a challenging problem for nuclear theorists [4,5,6,7,8]. The half-life formulas for β-decay can be expressed as a product of nuclear matrix elements (NMEs), involving the nuclear structure of the decaying parent and of the daughter nuclei, and the phase space factors (PSFs) that take into account the distortion of the electron wave function by the nuclear Coulomb field. For a precise calculation of the β-decay half-lives, an accurate computation of both these quantities is needed. Recently we recomputed the PSFs for positron decay and electron capture (EC) processes for 28 nuclei of astrophysical interest, using a numerical approach [16]. The new recipe for calculation can be extended to any arbitrarily heavy nuclei

Methods

Results

Conclusion