New calculations of gross<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>β</mml:mi></mml:math>-decay properties for astrophysical applications: Speeding-up the classical<i>r</i>process

TLDR

Recent experimental compilations of β‑decay half‑lives and neutron‑emission probabilities are benchmarked against improved global macroscopic‑microscopic model predictions. The authors employ a hybrid model that couples quasiparticle random‑phase approximation for Gamow‑Teller transitions with an empirical spreading of quasiparticle strength and a gross‑theory treatment of first‑forbidden decays, using nuclear masses from Audi 1995 or the finite‑range droplet model, and apply the resulting half‑lives and neutron‑emission probabilities up to the drip line in classical waiting‑point r‑process calculations. The new calculations yield a substantial improvement for spherical and neutron‑magic isotopes over earlier predictions and accelerate the r‑process flow, particularly at abundance peaks associated with magic neutron shells.

Abstract

Recent compilations of experimental gross $\ensuremath{\beta}$-decay properties, i.e., half-lives ${(T}_{1/2})$ and neutron-emission probabilities ${(P}_{\mathrm{n}}),$ are compared to improved global macroscopic-microscopic model predictions. The model combines calculations within the quasiparticle (QP) random-phase approximation for the Gamow-Teller (GT) part with an empirical spreading of the QP strength and the gross theory for the first-forbidden part of ${\ensuremath{\beta}}^{\ensuremath{-}}$ decay. Nuclear masses are either taken from the 1995 data compilation of Audi et al., when available, otherwise from the finite-range droplet model. Especially for spherical and neutron-(sub-)magic isotopes a considerable improvement compared to our earlier predictions for pure GT decay (ADNDT, 1997) is observed. ${T}_{1/2}$ and ${P}_{\mathrm{n}}$ values up to the neutron drip line have been used in r-process calculations within the classical ``waiting-point'' approximation. With the new nuclear-physics input, a considerable speeding-up of the r-matter flow is observed, in particular at those r-abundance peaks which are related to magic neutron-shell closures.