Magicity quenching in neutron-rich nuclei and its consequences on electron-capture rates during core collapse

Abstract

We study the impact of masses of very neutron-rich nuclei on matter composition and average electron capture rates during the late stages of pre-bounce evolution of core-collapsing massive stars. Inspired by experimental data which show magicity quenching in nuclei far from stability, we test the consequences of a possible quenching of shell closure in nuclei with N=50 and 82. By using parametrized equations for electron-capture rates and empirical modifications of the DufloZucker mass formula, we show that magicity quenching in neutron-rich nuclei may increase the electron-capture rates by up to 30%. Our results show the importance of new experimental data on nuclear masses and electron capture rates for neutron-rich nuclei in the vicinity of N = 50 and N = 82.