NSF Award
2311126
This award will advance understanding of the nature of neutron-rich atomic nuclei, with undergraduate student participation as an integral component. Experiments will be conducted at the Facility for Rare Isotope Beams (FRIB) at Michigan State University (MSU) using the Modular Neutron Array (MoNA) and the Large-area multi-Institutional Scintillator Array (LISA), both constructed and tested by undergraduate students from several institutions in the MoNA collaboration. The PIs, along with their team of undergraduate students and other collaboration members, will investigate the structure of light neutron-rich nuclei near the limits of their stability, which will provide tests for current theoretical models of nuclear structure. These weakly-bound or unbound nuclei exhibit different structures compared with their stable counterparts. They are produced by collisions of an accelerated beam of nuclei with a stable target. In order to test and improve upon the accuracy of computer simulation, critical for analysis of data and extraction of physics results from experimental data, the PIs also conduct experiments at the Los Alamos Neutron Science Center (LANSCE) at Los Alamos National Laboratory. These experiments will directly observe neutron scattering in 16 MoNA detectors as a test of the simulation. The collaboration has a long-standing tradition of involving undergraduate student participation at the heart of its research activities. This research program provides cutting-edge research opportunities for undergraduate students, helping to train the next generation of scientists.<br/><br/>The PIs and their undergraduate students will participate in two FRIB experiments using the Modular Neutron Array (MoNA), analyze recent and future data, and contribute to the improvement of Monte Carlo simulation used in data analysis. The two approved MoNA experiments at FRIB will study neutron-unbound states in neutron-rich nuclei (specifically 30F and 53Ca). The goal of the first experiment is to measure the 30F ground state for the first time, which will provide details on the structural changes in the fluorine isotopes. The goal of the second experiment is to better understand the N = 32 subshell closure by measuring unbound excited states in 53Ca. Both experiments provide data relevant for testing modern nuclear structure models. The PIs also seek to improve the computer modeling of neutron interactions in these plastic scintillators, critical for improving detector resolution and filtering of data for FRIB experiments. They will conduct a third approved neutron-scattering experiment at LANSCE using a diamond detector as active target in conjunction with 16 MoNA detectors. Two previous experiments by the PIs at LANSCE exposed some shortcomings of current simulation packages. The diamond detector, which consists only of C nuclei, allows for a focus on the neutron-carbon interactions that cause dark scattering in the plastic scintillators, which decrease position resolution in the array.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
