Authors
Dronchi, N.; Weisshaar, D.; Brown, B. A.; Gade, A.; Charity, R. J.; Sobotka, L.; Brown, K.; Reviol, W.; Bazin, D.; Farris, P.J.
Abstract
The B(E2,0+12+1) strengths of 36Ca and 38Ca are measured to be 131(20) e2fm4 and 101(11) e2fm4, respectively. The B(E2) value for 36Ca required a measurement of the p/ branching ratio because the 2+ state is proton unbound. This branching ratio is Bp=0.087(8). These B(E2) and branching-ratio values can be reproduced in the shell-model with the ZMB2 interaction, an interaction that predicts the Z=20 sd-shell closure is incomplete with large proton pf-shell occupancies in the ground state. These occupancies are at odds with other shell-model and energy-density-functional calculations of 36Ca. New data are used to provide an update on constraints of the density dependence of the symmetry energy through mirror charge-radii differences as well as to help reduce uncertainties of the astrophysical important 35K(p,) reaction.