Expanded calculations of proton–neutron quasi-particle random phase approximation (pn-QRPA) electron capture rates on 55Co for presupernova and supernova physics

Because of its abundance and its relatively high capture rates, 55Co is one of the key nuclide that can control the dynamics of core collapse of a massive star. Previously we introduced our microscopic calculations of capture rates on 55Co using the proton–neutron quasi-particle random phase approximation (pn-QRPA) theory. Here, we present for the first time an expanded calculation of the electron capture rates on 55Co on an extensive temperature-density scale. This type of scale is appropriate for interpolation purposes and of greater utility for simulation codes.PACS Nos.: 26.50.+x, 21.60.Jz, 23.40.–s, 27.40.+z

Collective bands in 80,82Kr

Deformed shell-model calculations are performed to study the structure of the collective bands in 80,82Kr. In our microscopic model, the single particle orbits 1p3/2, 0f5/2, 1p1/2, and 0g9/2 constitute the configuration space with 56Ni as the inert core. A modified Kuo interaction for this basis space is used in our calculation. The different levels are classified into collective bands on the basis of the B(E2) values among them. The calculated ground bands and quasi-gamma bands for both the nuclei agree reasonably well with experiment. The negative parity bands are also well-reproduced in our calculation. The calculated B(E2) values are compared with available experimental data. The nature of angular momentum alignment in the ground band is also discussed. PACS Nos.: 21.10.–k, 21.60.Jz, 27.50.+e