Pion induced fission evaluations for 208Pb, 209Bi, 232Th and 238U across the image resonance in the frame work of cascade-exciton model Original Research Article

Fission cross sections and fission probabilities have been calculated for positive and negative pion induced fission of 208Pb, 209Bi, 232Th and 238U in small steps across the (3,3) resonance using the cascade-exciton model code CEM95. The values of these quantities computed using CEM95 code exhibited reasonable agreement with those of experimental values found in literature. In this selected energy interval, fission cross sections of 232Th and 238U depicted an increase with an increase in the energy of incident pion, reaching a maximum value and then decreasing, however fission probabilities remained unchanged. For 208Pb and 209Bi, both fission cross sections and probabilities indicated an increasing trend. Cross sections for actinides are found to be less dependent on the ratio of the level density parameters as compared to preactinidies. No significant change in the reaction mechanism was observed in the selected energy range.