Shell-model calculations of stellar weak interaction rates:: II.: Weak rates for nuclei in the mass range A=45-65 in supernovae environments

Based on large-scale shell-model calculations we have determined the electron capture, positron capture and beta-decay rates for more than 100 nuclei in the mass range A = 45-65. The rates are given for densities rho Y(e) = 10(7)-10(10) mol/cm(3) and temperatures T = 10(9)-10(10) K and hence are relevant for both types of supernovae (Type Ia and Type II). The shell-model electron capture rates are significantly smaller than currently assumed. For proton-to-baryon ratios Y(e) = 0.42-0.46 mol/g, the beta-decay rates are faster than the electron capture rates during the core collapse of a massive star. (C) 2000 Elsevier Science B.V. All rights reserved.