Windows on the Universe: Study of Open Quantum Systems in Atomic Nuclei

Michigan State University, East Lansing MI

Investigators

Abstract

This award supports research to understand how protons and neutrons interact when they are in a nucleus having far more neutrons than protons, also known as rare isotopes. These neutron-rich rare isotopes straddle the limit of existence, which defines the neutron drip line, where protons and neutrons no longer form a nucleus because they become energetically unbound. The structure and properties of these isotopes are relevant for understanding astrophysical processes. This research will be conducted at scientific user facilities including the National Superconducting Cyclotron Laboratory (NSCL), soon to become the Facility for Rare Isotope Beams (FRIB). Part of this research program will be performed with the MoNA detector and the MoNA Collaboration, which consists of a group of undergraduate institutions that has had a major impact on recruiting students to STEM fields. The award includes support for students and faculty from HBCUs and other Minority Serving Institutions to go to NSCL/FRIB and collaborate on experiments for two-week long periods in the summer. This award supports experimental studies of weakly bound atomic nuclei in order to test nuclear models that are relevant to understanding open quantum systems and astrophysical processes in the universe. Proper modeling and understanding of continuum effects are important in the era of multi-messenger astronomy where nuclear properties, such as binding energies, are relevant for interpreting optical, neutrino, and gravitational-wave observations. It will address fundamental questions, such as what combination of neutrons and protons can form an atomic nucleus and perhaps double our knowledge of the neutron drip line. The team will use the powerful tools of the MoNA Collaboration along with the wide range of new nuclei accessible at FRIB to measure properties of unbound states. New techniques will be developed to exploit quasi-elastic proton removal reactions to probe states near the particle emission threshold and the structure of weakly-bound nuclei. Finally, due to the open-quantum nature of the states of interest, the reaction mechanism to produce these states becomes an important part of the measurement. The role of the reaction mechanism in the context of open quantum systems will be explored. This award addresses and advances the goals of the Windows on the Universe Big Idea. 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.