Neutrino-induced charged-current reaction rates for r-process nuclei

Neutrino-induced reactions play an important role during and after the r-process if it occurs in an environment with extreme neutrino fluxes, as in the neutrino-driven wind model or neutron star mergers. The neutrino reactions can excite the daughter nucleus above the neutron threshold, which is quite low for r-process nuclei. Thus the daughter nucleus will decay by emission of one or several neutrons. We have calculated the relevant total (nu(e), e(-)) cross sections as well as the partial neutron spallation cross sections for r-process nuclei with neutron numbers N = 41-135 and proton numbers Z = 21-82. The supernova neutrino spectrum is described by a Fermi-Dirac distribution with various temperature parameters between T = 2.8 MeV and T = 10 MeV and with the degeneracy parameters alpha = 0 and alpha = 3. Our calculations of the nuclear response are based on the random phase approximation and consider allowed as well as forbidden transitions. (C) 2001 Elsevier Science.