Neutrino Capture on Heavy Nuclei

We examine the process of electron neutrino and electron antineutrino capture on nuclei with masses {ital A}{approx_gt}40 in the context of the post{endash}core-bounce supernova environment. We discuss the influence of final-state electron blocking, extended distributions of Gamow-Teller strength, and the Coulomb wave correction factor on neutrino and antineutrino capture rates. We study the effect of discrete state transitions and the thermal population of excited states on these rates. We estimate the strength of forbidden capture channels and discuss their importance in neutrino capture rate estimates. We find that forbidden strength can dominate the antineutrino capture rates on neutron-rich nuclei which are blocked and have no allowed transitions. Forbidden weak strength may be important in other cases of neutrino or antineutrino capture as well, depending on the excitation energy distribution of this strength. In addition, the importance of neutrino capture relative to antineutrino capture on both heavy nuclei and free nucleons is discussed. Formulae for calculating these rates in the context of the post{endash}core-bounce supernova environment are presented. Tables of rates are provided for some key nuclei. A FORTRAN code for calculating rates is available on request. {copyright} {ital 1995 The American Astronomical Society.}