Energy levels of 94Nb populated directly via the (n, γ) reaction

Abstract

The 93Nb(n, γ)94Nb reaction has been used to explore the level structure of 94Nb to an excitation energy of 3900 keV. Although selection rules for this reaction do limit the states that can be directly populated, in this case the rich resonance structure and the p-wave strength enhance the number of possibilities. The present study, for which exceedingly high statistical precision has been attained, reveals a total of 334 transitions that if assumed to be of a primary nature, can be directly associated with levels. The neutron separation energy, based upon the mass scale via the 14N(n, γ)15N reaction, is found to be 7227.51 ± 0.09 keV. This is significantly lower than the currently accepted value of 7229.5 ± 0.5 keV. While the energies of low-lying states are found to have values in agreement with those deduced using the most recent crystal spectrometer measurements, significant deviations are observed for levels above 900 keV. The completeness of the study has permitted examination of statistical nuclear properties, such as the energy dependence of the level density and the photon transition strength.