Intensities and Angular Distributions of Ground-State Rotational Transitions Excited in (α, 3n) and (α, 4n) Reactions

Abstract

Relative intensities measured for rotational transitions in the ground-state bands are reported for residual even-even rare-earth nuclei excited in ($\alpha , 3n$) and ($\alpha , 4n$) reactions. The incident $\alpha$-particle energy was typically ∼40.5 MeV, and the targets were isotopes of Gd, Dy, Er, and Yb. The angular distributions of the rotational radiations were found to be in accord with theoretical expectations. The relative intensities of the lines were, however, inconsistent with the implications of simple statistical models. More angular momentum is apparently carried away by photon transitions connecting higher-lying states than one might expect. Possible reasons for this discrepancy are briefly discussed.