Anomalous electron scattering from 142, 146, 150Nd

Abstract

Properties of the ground state charge distributions and some low-lying states in 142, 146, 150Nd have been investigated using the Yale University Electron Accelerator. The incident energy was varied between 15 MeV and 60 MeV while angular distribution measurements were obtained at angles between 70° and 150° inclusive. If the ground state charge distribution is described in terms of a half-density radius and a skin thickness, a conventional phase-shift analysis of the present results, in the context of spherically symmetric static charge distributions, indicates anomalously small values of the skin thickness in all three neodymium isotopes. Measured cross sections differ by as much as 40 % from those expected for these nuclei on the basis of the results of muonic X-ray and high-energy electron scattering experiments. Estimates by Rawitscher of the effect of virtual nuclear excitations suggest that these excitations (neglected in the analysis) may be responsible for the observed anomalies. Reduced γ-transition probabilities have been deduced for the following low-lying levels: 142Nd, 1.57 MeV (2 +), 2.09 MeV (3 −, (2 +?)); 146Nd, 0.45 MeV (2 +); 150Nd, 0.13 MeV (2 +).