Neutron-Resonance Spin Determinations inNd143andNd145from Capture Gamma-Ray Measurements

Abstract

Spin assignments have been made for 47 neutron resonances in the target nuclei ${\mathrm{Nd}}^{143}$ and ${\mathrm{Nd}}^{145}$ by two independent methods: measurement of coincidences between cascade capture $\ensuremath{\gamma}$ rays, and measurement of the ratio of low-energy $\ensuremath{\gamma}$-ray intensities. A new method for analyzing data of this type is introduced which enables us to assign a probability of correctness to each spin measurement. The use of an energy window rather than an integral bias level for the coincidence experiment improves the separation of the two spin groups. The $s$-wave strength function does not appear to be spin-dependent. The distribution of the spin values is consistent with a $2J+1$ level-density dependence.