Properties of112Cdfrom the(n,n′γ)reaction: Levels and level densities

Abstract

Levels in ${}^{112}\mathrm{Cd}$ have been studied through the ${(n,n}^{\ensuremath{'}}\ensuremath{\gamma})$ reaction with monoenergetic neutrons. An extended set of experiments that included excitation functions, $\ensuremath{\gamma}$-ray angular distributions, and $\ensuremath{\gamma}\ensuremath{\gamma}$ coincidence measurements was performed. A total of 375 $\ensuremath{\gamma}$ rays were placed in a level scheme comprising 200 levels (of which 238 $\ensuremath{\gamma}$-ray assignments and 58 levels are newly established) up to 4 MeV in excitation. No evidence to support the existence of 47 levels as suggested in previous studies was found, and these have been removed from the level scheme. From the results, a comparison of the level density is made with the constant temperature and back-shifted Fermi gas models. The back-shifted Fermi gas model with the Gilbert-Cameron spin cutoff parameter provided the best overall fit. Without using the neutron resonance information and only fitting the cumulative number of low-lying levels, the level density parameters extracted are a sensitive function of the maximum energy used in the fit.