Abstract: Research on beta-delayed neutron emission experiences periodic revivals. The seasons of popularity are inevitably linked to newly acquired capabilities to produce more exotic neutron-rich isotopes. This two-step decay process is a prevalent type of radioactivity on the neutron-rich side of the chart of nuclei. Still, the most interesting beta-n precursors are inherently difficult to access experimentally. Modern radioactive ion-beam facilities now provide another opportunity to expand the pool of isotopes to study. Some of the ​“best” isotopes can be produced and measured this time, and the opportunities to explore individual aspects of beta-delayed neutron emission are unique.

We have carried out experiments that investigate a range of isotopes from Z=8 to Z=80 using neutron counters and neutron energy spectrometers to explore the value of this process for the fundamental understanding of the nucleus and for astrophysical and nuclear energy applications. Traditionally, detailed studies of beta-n inform on decay strength distribution and can provide new data on excited states populated in decay daughters. In addition, beta-delayed neutron-emission branching ratios are needed for astrophysics and r-process modeling. However, the availability of nuclei with large decay energy windows enabled in-depth investigations to understand the foundations of beta-n. New experimental data will be presented, which will shed new light on the mechanism of beta-delayed neutron emission. In addition, brand-new and exciting results from the neutron spectroscopy from the first FRIB experiments using FRIB Decay Station Initiator (FDSi) will be shown.

This research was sponsored by DOE  NNSA (DOE DE-NA0003899, DE- NA0004068), DOE Office of Science  (DE-FG02-96ER40983,  DE-AC05-00OR22725), and NSF  (NSF-MRI- 1919735).