Measurement of the Nuclear Level Density at High Spins

Abstract

The neutron spectrum from the reaction $^{92}\mathrm{Zr}(^{64}\mathrm{Ni},1n)^{155}\mathrm{Er}$ has been measured at an average spin of $52\ensuremath{\hbar}$ and for excitation energies between 30 and 36 MeV in $^{155}\mathrm{Er}$. Channel and spin selection have been obtained from the Darmstadt-Heidelberg Crystal Ball. The level density in $^{155}\mathrm{Er}$ is derived within the framework of a Fermi-gas model. A level-density parameter of $a=\frac{A}{(8.8\ifmmode\pm\else\textpm\fi{}1.3)}$ ${\mathrm{MeV}}^{\ensuremath{-}1}$ is deduced.