The Precision Frontier at FRIB: Masses, Radii, Moments, and Fundamental Interactions

Michigan State University, East Lansing MI

Investigators

Abstract

What are the underlying forces and constituents of atomic nuclei? An answer to this question is revealed through the basic nuclear properties of matter such as the mass, charge radius, and decay of atoms into other atoms. The Precision Measurements group at FRIB will perform experiments to determine atomic masses, nuclear radii, and extend the search for exotic decays of nuclei. The measurements are designed to extract the fundamental properties of nuclei, with large neutron to proton ratios, which can only occur in Nature during extreme astrophysical events. The research has implications for nuclear structure physics, nuclear astrophysics and the interpretation of multi-messenger astrophysical signals. The work proposed here will also provide significant contributions to the NSF Big Idea “Windows on the Universe” through measurements that improve the interpretation of signals observed in multi-messenger astrophysical events. The Precision Measurements group will take advantage of the unprecedented capabilities of the Facility for Rare Isotope Beams (FRIB) to create beams of unusual isotopes and to measure their properties. There are three main thrusts in the project. First, measuring atomic masses. These measurements are of direct importance for understanding nucleosynthesis in extreme astrophysical environments and as probes of nuclear structure at the edge of stability. In addition, with adequately precise measurements, the PIs can test fundamental symmetries in Nuclear and Particle Physics. Second, nuclear radii and electromagnetic moments. Measurements of the properties of mirror nuclei will contribute to our understanding of the nuclear equation of state, which is particularly relevant for the understanding the merging of binary neutron stars. In addition, ground-state measurements in a variety of systems test nuclear-structure theory. Third, exotic interactions. Measurements with exotic nuclei, polarized nuclei, and positronium will test fundamental symmetries. In addition, these measurements test the extremes of basic nuclear theory. The measurements will be performed on the FRIB stopped-beam line using, for example, a Penning Trap and local laser facilities. These tools will also be made available to other users of the FRIB facility. 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.