The (He 3, α) reaction on C 13

Abstract

Angular distributions of alpha particles leading to the 0 + ground state and the 2 + first excited state of C 12 have been obtained for the bombarding energies of 8.82, 9.44 and 10.3 MeV. Those leading to the 0 + second excited state were obtained in the forward cone up to 80°. The ground state distributions show forward peaks sensitive to the bombarding energy and strong backward peaks at all energies. The first excited state distributions show strong forward and backward peaks at all energies. The second excited state distributions are forward-peaked with cross sections changing rapidly with the bombarding energy. Analysis of the data has been made in terms of the neutron pickup process by using the Oak Ridge distorted wave Born approximation programme. General features of the ground state and the first excited state distributions, including the strong backward peaks and the various secondary maxima, are found to be accounted for by the pickup process alone. The ratio of the spectroscopic factor for the transition to the first excited state to that for the transition to the ground state is found to be 1.29, in agreement with calculations of Macfarlane and French based on the Rosenfeld exchange mixture.