Post-Neutron Mass Yield Distribution in the Epi-Cadmium Neutron-Induced Fission of ²³⁸Pu

The cumulative and independent yields of various fission products within the mass range of 78 to 157 have been measured in the epi-cadmium neutron-induced fission of Pu-238 by using an off-line ?-ray spectrometric technique. The lower yield of I-136 than the usual trend indicates the formation of delayed neutron emitter I-137. From the cumulative yields, post-neutron mass chain yields were obtained by using the charge distribution correction. From the mass yield data, the peak-to-valley (P/V) ratio, the full-width at tenth-maximum of light and heavy mass wings, the average light mass and heavy mass as well as the average number of neutrons emitted were obtained. The mass chain yield data in the Pu-238(n,f) reaction were compared with similar data of the Pu-238(n(th),f) reaction to examine the role of excitation energy on the nuclear structure effect and P/V ratio.