Nuclear structure effects in hot environments

Wendell Misch, Shanghai Jiao Tong University, China
Friday, Dec 07, 11:00 AM - FRIB Theory Fellow Candidate Seminar
1200 FRIB Laboratory

Abstract:  Nuclear reactions are key inputs to stellar evolution, nucleosynthesis, and other astrophysical models. Especially in hot environments, the structure of the reacting nuclides impacts both reaction rates and, in the case of weak interactions, the resulting neutrino spectra. I will present some of my recent work in this area, which includes the impact of nuclear structure on expected neutrino signals from nearby pre-supernova stars. It may be possible to detect neutrinos from nearby pre-supernova stars. Leading up to core collapse, beginning around silicon burning, nuclei become dominant producers of neutrinos, particularly at higher neutrino energy, so a systematic study of nuclear neutrino spectra is desirable. My collaborators and I have done such a study using shell model calculations and a modified Brink-Axel hypothesis in sd-shell nuclei which includes neutrinos produced by charged lepton capture, charged lepton emission, and neutral current nuclear deexcitation. Previous authors have tabulated the rates of charged current nuclear weak interactions in astrophysical conditions, but the present work expands on this not only by providing neutrino energy spectra, but also by including the heretofore untabulated neutral current deexcitation neutrino pairs. Extension of the study to heavier mass regions using state-of-the-art shell models has been planned and is currently in the initial phases. Time permitting, I will also present some work on the behavior of nuclear isomers.