Mass-yield variations in the thermal and epi-thermal fissions of 239Pu

Mass-yield ratios of 77Ge and 77As from thermal and epi-Cd fissions, and of 77Ge and 166Dy166Ho from thermal and epi-Sm fissions of 239Pu have been measured radiochemically. It was found that the epi-thermal fission yield of the 77-mass chain showed only a slight decrease, if any, compared with fission caused by thermal neutrons, while the epi-Sm fission yield of 166Dy166Ho was found to be lowered by 30 per cent. The Ge(Li) γ-ray …