$β$-Decay Half-Lives of 55 Neutron-Rich Isotopes beyond the N=82 Shell Gap

Published 31 Mar 2020 in nucl-ex | (2004.00119v1)

Abstract: The $\beta$-decay half-lives of 55 neutron-rich nuclei $^{{134-139}$Sn,} $^{{134-142}$Sb,} $^{{137-144}$Te,} $^{140-146}$I, $^{{142-148}$Xe,} $^{{145-151}$Cs,} $^{{148-153}$Ba,} $^{151-155}$La were measured at the Radioactive Isotope Beam Factory (RIBF) employing the projectile fission fragments of $^{238}$U. The nuclear level structure, which relates to deformation, has a large effect on the half-lives. The impact of newly-measured half-lives on modeling the astrophysical origin of the heavy elements is studied in the context of $r$ process nucleosynthesis. For a wide variety of astrophysical conditions, including those in which fission recycling occurs, the half-lives have an important local impact on the second ($A$ $\approx$ 130) peak.