Beta transition rates in hot and dense matter.
Abstract
The gross theory of beta decay is used to calculate betatransition rates for stellar conditions of high temperature and density. The formalism employed is outlined, with attention given to stellar and laboratory betatransition rates, beta strength functions, singleparticle spectra, model configurations, and spinparity selection rules. The calculated betatransition rates for A = 56 isobars are presented and compared with the results of other authors. Transition rates and neutrino energy losses in various elementary processes are computed numerically and with the aid of approximate formulas; the processes include p + e() yields n + an electron neutrino, n + e(+) yields p + an electron antineutrino, and n decays into p + e() + an electron antineutrino. As applications of the elementary processes, the neutron/proton ratio for exploding hot dense matter is calculated, and variations in the total neutron/proton ratio during the expansion and cooling of matter from peak conditions of temperature and density in the early phase of a model supernova explosion are examined. Approximate formulas for the Fermi integrals in the nonrelativistic regime are also provided.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 July 1978
 Bibcode:
 1978A&A....67..185T
 Keywords:

 Beta Particles;
 Electron Density (Concentration);
 Forbidden Transitions;
 Nuclear Fusion;
 Supernovae;
 Energy Dissipation;
 Formalism;
 Galactic Nuclei;
 Neutrinos;
 Nonrelativistic Mechanics;
 Particle Interactions;
 Plasma Decay;
 Astrophysics;
 Dense Matter:Nucleosynthesis