New measurements reveal longer-than-expected lifetimes in neutron-rich nuclei

Researchers measured 15 previously unknown beta-decay half-lives for neutron-rich isotopes near calcium-54, providing new insight into how nuclear structure changes in this region of the nuclear chart that is important for modeling processes that occur in the crusts of neutron stars. In an experiment performed at FRIB using the FRIB Decay Station initiator (FDSi), the team developed a new method for determining nuclear lifetimes while accounting for uncertainties caused by beta-delayed neutron emission. The measurements revealed an unexpected change in half-life trends for nuclei with 34 neutrons, with nuclei beyond this point living longer than anticipated. Comparisons with theoretical models showed that these results reflect the influence of nuclear shell structure and interactions among protons and neutrons in these exotic systems. The study helps improve models used to describe nuclei near the limits of stability and in astrophysical environments.

Their paper (“Beta-Decay Half-Lives beyond 54Ca: A Systematic Survey of Decay Properties Approaching the Neutron Dripline”) was published in Physical Review Letters.