Studies in Astrophysics, Nuclear Physics, and Particle Physics

Ohio State University Research Foundation -Do Not Use, Columbus OH

Investigators

Abstract

A very exciting development of the past decade in nuclear astrophysics has been that of beams of short-lived nuclides, often those along the pathways of processes of explosive nucleosynthesis, and sometimes critical to their progression. Notably, the r-process is thought to occur near thecore of a supernova in a fraction of a second, and to synthesize half thenuclei heavier than iron. It occurs in a hot neutron-rich environment, passing through nuclei that are 20 neutrons beyond stability. One componentof the research will be to measure half-lives and structure of nuclei along the r-process path, thus greatly improving our understanding of ther-process. Another process, the p-process, occurs in a high-temperature hydrogen-rich environment in tens of seconds, as matter from one star is accreted onto either a white dwarf or neutron star companion. The result can be a nova or an x-ray burst. This process proceeds by successive proton-capturenreactions and beta-decays through nuclei a few protons to the proton-rich side of stability, but has critical points at which it may require a beta-decay in order to proceed unless the next reaction proceeds very rapidly. Thus it is important to measure proton-capture reaction rates on the unstable nuclei along its pathway in order to understand how it synthesizes nuclei and generates energy. We plan to study several crucial p-process reactions. The final component of the program involves the Observatory for Multiflavor NeutrInos from Supernovae. OMNIS will detect several thousand events, mostly from "e-neutrinos", from the next galactic supernova. But, because of "neutrino oscillations" recently established by the Super-K and SNO neutrino observatories, these will actually reflect the energy distributions of the more-difficult-to-detect mu- and tau-neutrinos just as they emerge from the very core of the exploding supernova. OMNIS' data will enable a variety of results, ranging from (1) diagnosis of the stellar collapse process at a level that will test for several recently hypothesized effects, (2)direct measurement of neutrino masses several orders of magnitude more accurately than some present results, (3) determination of poorly determined neutrino oscillation modes, (4) observation of the signatures of someprocesses of nucleosynthesis, and (5) possible observation of the sharp neutrino luminosity termination that would signal the collapse to a blackhole.