Affiliation: College of Arts and Sciences, Department of Physics and Astronomy
The rapid neutron-capture process (r process) is responsible for synthesizing approximately half of the
heavy elements in the solar system, but after decades of work the astrophysical site where it occurs is unknown.
Because a very large number of heavy, neutron-rich nuclei are populated during the r process, theoretical
efforts to locate the r-process site require a tremendous amount of nuclear physics input. However, most
nuclei populated during the r process are very neutron-rich and unstable, and many r-process nuclei cannot
be studied experimentally. As a result, the basic properties of a large number of heavy, deformed, short-lived
nuclei must be calculated with reliable nuclear models.
β-decay half-lives are among the most important properties that affect r-process abundances. In this
work we present a new, efficient method for calculating β-decay half-lives of heavy, deformed nuclei: the
proton-neutron finite amplitude method (pnFAM). We apply the pnFAM to calculate half-lives of nuclei that
demonstrate the strongest effects on r-process abundances in the A≃80 and A≃160 mass regions, including
even-even, odd-A, and odd-odd nuclei. We find that our calculations result in half-lives very similar to those
reported in previous studies, with correspondingly small effects on r-process abundances.