Description:Electron capture on nuclei, nuclear structure, nuclear physics input for supernova modelling
Abstract:A set of computer programs calculating electron capture rates within several nuclear structure models. Modelling of core-collapse supernova requires nuclear input in terms of electron capture rates. Nuclear structure information from the best available nuclear models is used to calculate electron capture rates in the thermal environment of a collapsing star. Both the total and the partial electron capture rates as well as the emitted neutrino spectra are calculated for many nuclei and averaged for the stellar conditions. These rates and spectra are calculated for around 3000 nuclei and averaged according to the abundances at given stellar conditions.
The rates (and spectra) for 100 sd shell nuclei are estimated from the Fuller, Fowler, and Newman rates, taking into account the screening effects of the media. The rates for 100 pf shell nuclei (A=45-65) are calculated from the spherical shell model estimation of the Gamow-Teller distributions. Heavier nuclei are calculated within the hybrid approach based on the Shell Model Monte-Carlo (SMMC) and the random-phase approximation (RPA). These nuclei are limited to the mass range A=66-112. Around 2500 nuclei are calculated having replaced the results of the SMMC approach by those from a schematic Fermi-Dirac distribution. These nuclei cover Z=28-80 and N=40-160. The screening effects in the last three approaches are taken into account directly.
Calculation goes in two steps. First, the electron capture partial cross-sections for the SMMC+RPA and FD+RPA approaches are obtained. Calculation for specific nuclei can fail, thus they may need to be resubmitted. Final data in binary format takes around 5GB. Intermediate results exceed this number by a factor larger than 2. At this step the rates and the emitted neutrino spectra are calculated as well for checking purposes. 9 computer codes produce the partial-cross sections and 2 codes calculate the rates and the spectra. Work inside a grid job is managed by 3 scripts. At the seco