Energy and linear-momentum dissipation in the fusion reaction of 165Ho + 20Ne at 30 MeV/nucleon.

Abstract

Neutron energy spectra were measured at angles between 14\ifmmode^\circ\else\textdegree\fi{} and 159\ifmmode^\circ\else\textdegree\fi{} in coincidence with evaporation residues as a function of linear-momentum transfer in reactions of $^{165}\mathrm{Ho}$ with 600 MeV $^{20}\mathrm{Ne}$. In addition, angular distributions and absolute cross sections for elastic scattering, fission, and evaporation residues have been measured. The preequilibrium component of the neutron spectra has been parametrized with a hot-moving-source fit. For the highest linear-momentum transfer the forward-to-backward anisotropy in the angular distribution is smallest and the quality of the fit is best. From the temperature and multiplicity of evaporated neutrons the level density parameter of nuclei with A\ensuremath{\approxeq}180 has been determined to be a=A/(10.5\ifmmode\pm\else\textpm\fi{}1) ${\mathrm{MeV}}^{\mathrm{\ensuremath{-}}1}$ at excitation energies of 300 to 400 MeV.