Electric Excitation of Certain Rare-Earth Nuclei by Protons

Abstract

Sixteen energy levels have been observed in thirteen isotopes of samarium, europium, gadolinium, and terbium. Electric quadrupole transition probabilities have been determined for some of these energy levels from the measured electric excitation cross sections. For the even-$A$ isotopes of Gd, the properties of the low-lying energy levels are in good agreement with the expectations of the "strong coupling" rotational model. The first energy levels in the even isotopes of samarium show the sharp break in the position of the first excited level which has recently been pointed out by Scharff-Goldhaber. In general, the results are in good qualitative agreement with the predictions of the collective model; however, the moments of inertia for the rotational levels observed in this region are substantially larger than those expected from the intrinsic deformations obtained from the radiative transition probabilities.