Stellar weak-interaction rates for rp-process waiting-point nuclei from projected shell model

Abstract

We propose a projected shell model (PSM) for description of stellar weak-interaction rates between even-even and odd-odd nuclei with extended configuration space where up to six-quasiparticle (qp) configurations are included, and the stellar weak-interaction rates for eight rp-process waiting-point (WP) nuclei, 64Ge, 68Se, 72Kr, 76Sr, 80Zr, 84Mo, 88Ru and 92Pd, are calculated and analyzed for the first time within the model. Higher-order qp configurations are found to affect the underlying Gamow-Teller strength distributions and the corresponding stellar weak-interaction rates. Under rp-process environments with high temperatures and densities, on one hand, thermal population of excited states of parent nuclei tends to decrease the stellar β+ decay rates. On the other hand, the possibility of electron capture (EC) tends to provide increasing contribution to the rates with temperature and density. The effective half-lives of WP nuclei under the rp-process peak condition are predicted to be reduced as compared with the terrestrial case, especially for 64Ge and 68Se.