ISOMER RATIOS OF 134CS FORMED IN FISSION OF 233U AND 235U BY PROTONS OF ENERGIES 20-85 MEV

The isomer ratios of 134Cs formed in the fission of 233U and 235U by protons of energies 20-85 MeV have been determined experimentally. Calculations have been made for these isomer ratios on the basis of a statistical theory of the spin distribution of the primary fragments. The root-mean-square angular momentum, √J2, characterising the spin distribution of the primary fragments, varies between 12 h{stroke} at 20-30 MeV and 18 h{stroke} at 85 MeV in 233U fission, whereas it is about 16 h{stroke} in 235U fission throughout this energy region. The relatively large values of √J2 indicates that a fraction of the angular momentum of the fissioning nucleus appears as the intrinsic spin of the primary fragments in agreement with other published data. © 1969.