β-decay half-lives of 55 neutron-rich isotopes beyond the N=82 shell gap

Abstract

The β-decay half-lives of 55 neutron-rich nuclei Sn134-139, Sb134-142, Te137-144, I140-146, Xe142-148, Cs145-151, Ba148-153, and La151-155 were measured at the Radioactive Isotope Beam Factory employing the projectile fission fragments of U238. 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 ≈ 130) peak.