Level densities of Ge74,76 from compound nuclear reactions

Abstract

The level densities of $^{74,76}\mathrm{Ge}$ nuclei are studied with $^{68,70}\mathrm{Zn}(^{7}\mathrm{Li},\mathrm{Xp})$ reactions. Proton evaporation spectra are measured at backward angles in a wide energy region, from about 2 to 25 MeV. The analysis of spectra allows for the testing of level density models used in modern reaction codes for practical cross-section calculations. Our results show that at excitation energies above the discrete level region, all level density models tested in this work overestimate the level densities that are needed to reproduce proton spectra from these reactions. The Gilbert and Cameron model, which includes the constant-temperature energy dependence of the level density, shows the best agreement with experiment, however, its parameters need to be adjusted to reflect the observed reduction of the level density at higher excitation energies.