Electric and Magnetic Dipole Strength at Low Energy

A low-energy enhancement of radiative strength functions was deduced from recent experiments in several mass regions of nuclei, which is believed to impact considerably the calculated neutron capture rates. In this Letter we investigate the behavior of the low-energy gamma-ray strength of the Sc-44 isotope, for the first time taking into account both electric and magnetic dipole contributions obtained coherently in the same theoretical approach. The calculations are performed using the large-scale shell-model framework in a full 1h omega sd-pf-gds model space. Our results corroborate previous theoretical findings for the low-energy enhancement of the M1 strength but show quite different behavior for the E1 strength.