Analysis of (sup 209) Bi and (sup 238) U photofission cross section in the quasi-deuteron region of photonuclear absorption

摘要

An analysis of the photofission reactions in the quasi-deuteron energy range of photonuclear absorption ((approx) 30-140 MeV) has been performed for (sup 209) Bi and (sup 238) U nuclei. Experimental cross section data available in the literature have been compared with calculated values obtained from a model in which the incoming photon is assumed to be absorbed by a neutron-proton pair (Levinger's quasi-deuteron photoabsorption), followed by a mechanism of evaporation-fission competition for the excited residual nuclei. The model has been shown to reproduce the main experimental features of (sup 209) Bi and (sup 238) U photofission cross section, although unexplained differences still remain in the case of (sup 238) U-fission by 30-50 MeV incident photons. (author). 49 refs, 10 figs, 2 tabs. (Atomindex citation 26:061452)