Gamma-ray and neutron emission from hot nuclei

This paper reports on neutrons and high energy γ-rays that were measured in coincidence with fusion residues produced in the Ni, 92Mo, 122Sn + 40Ar reactions at E/A = 21 and 26 MeV. The neutron data indicate the formation of equilibrated nuclei with excitation energies up to 5 MeV/nucleon. The deduced level density parameter is consistent with A/8 for excitation energies from 2.5 to 5 MeV/nucleon. The γ-ray spectra were compared with statistical calculations for γ-ray transitions from highly excited nuclei. Contributions of bremsstrahlung in the early stages of the reaction were subtracted. The evolution of the GDR γ-ray yields and the shape of the γ-ray spectra are well reproduced by calculations in which the width of the GDR increases with the excitation energy