BINARY AND TERNARY SPONTANEOUS FISSION IN 252 Cf

Triple coincidence data from the fission of 252 Cf were used to deduce the intensity of the proposed second mode in barium channels by using the γ − γ − γ coincidence relations and Gammasphere. An upper limit of 1.25% was found for the relative intensity of the second mode in the Ba-Mo case. Yields for cold ternary and cold binary fission were extracted from intensities of γ-ray transitions originating from the de-excitation of primary and secondary fragments. The relative 4 He and 5 He ternary fission yields were determined from a careful analysis of the energy distribution of α spectra from a new measurement with a 252 Cf source and from published data on 252 Cf and 235 U(n,f). The kinetic energies of the 5 He and 4 He ternary particles were found to be approximately 11 and 16 MeV, respectively. 5 He particles contribute 10-20% to the total alpha yield with the remainder originating from ternary fission accompanied by the emission of 4 He. A number of correlated pairs are identified in ternary fission with 10 Be as the LCP. We observed only cold, 0n 10 Be and little, if any, hot, xn 10 Be channel.