Study on gamma-ray strength functions and energy spectra in the neutron radiative capture of Au-197

The aim of this paper is to explain theoretically the abnormal protuberance s near and after 5.5 MeV in the gamma spectra of the (n, gamma) reactions f or the nulei in the regions of 110 less than or equal to A less than or equ al to 140 and 180 less than or equal to A less than or equal to 210. Supposing that in the primary and cascade gamma de-excitation processes of the compound nucleus, besides the giant dipole resonance model, there exist the deexcitation processes of the excited states of He-6, Li-6, Be-6, Li-7 and Be-7 particle Clusters, the gamma -ray strength function in which thes e processes are contained was constructed. The (n, gamma) reaction cross se ctions and the gamma energy spectra in the neutron incident energy region f rom 0.01 MeV to 3MeV for Au-197 were calculated. The results are in better coincidence with the experiments. Especially for the gamma energy spectra, the abnormal protuberances near and after 5.5MeV were reproduced very well.