Gamow-Teller Transitions from 56Ni

A new technique to measure (p,n) charge-exchange reactions in inverse kinematics at intermediate energies on unstable isotopes was successfully developed and used to study the 56Ni(p,n) reaction at 110 MeV/u. Gamow-Teller transition strengths from 56Ni to 56Cu were obtained and compared with shell-model predictions in the pf-shell using the KB3G and GXPF1A interactions. The calculations with the GXPF1A interaction reproduce the experimental GT strength distribution much better than the calculations that employed the KB3G interaction, indicating deficiencies in the spin-orbit and proton-neutron residual potentials for the latter. The results are important for improving the description of electron-capture rates on nuclei in the iron region, which are important for modeling the late evolution of core-collapse and thermonuclear supernovae.