Determination of the Gamow-Teller transition strength to In-116(g.s.) by the Cd-116(p,n) reaction at 300 MeV for the study of the nuclear matrix element of the two-neutrino double beta decay

摘要

The Cd-116(p,n) experiment at 300 MeV has been performed for deducing the Gamow-Teller (GT) transition strengths B(GT(-)) in In-116. For the transition to the ground state, the B(GT(-)) value of 0.26 +/- 0.02 is obtained. From this B(GT(-)) value and the B(GT(+)) value by a beta-decay experiment, the contribution of the intermediate ground state of In-116 to the nuclear matrix element is deduced to be 0.070 +/- 0.003. The B(GT(-)) value obtained herein is a factor of 8 less than that obtained from a previous (He-3,t) measurement. This discrepancy, as well as differences in the distribution of low energy CT strength, and the width and peak energy of the GT giant resonance may be explained if the target used in the (He-3,t) measurement is a Cd target with natural abundance.