NEUTRINO CAPTURE AND SUPERNOVA NUCLEOSYNTHESIS

We investigate charged current neutrino and antineutrino capture on nuclei in the post-core bounce supernova environment. We point out that these processes may play an important, and heretofore overlooked, role in determining the nucleosynthesis in models of neutrino-heated supernova ejecta. In particular, we suggest that inclusion of these rates may help solve the problem in these models of overproduction of nuclides with neutron numbers near 50 and, in addition, enhance the production of the some of the light p-process nuclei in the alpha-process, particularly Mo-92. The neutrino capture rates on neutron-rich nuclei are found to be dominated by transitions to the Fermi (isobaric analog state) and Gamow-Teller resonances. In these cases, the neutrino capture thresholds are approximately just the nuclear Coulomb energy differences between nuclear parents and daughters, and the neutrino capture rates therefore exhibit only weak dependence on neutron and proton numbers compared to that of beta(-)-decay rates. We exploit this property to constrain the location of the r-process region in the post-core bounce supernova environment. We present analytic estimates for the rates of electron neutino and antineutrino capture on nuclei and nucleons.