He and Be ternary spontaneous fission of 252 Cf

Ternary and binary fission studies of 252 Cf have been carried out by using the Gammasphere detector array with light charged particle (LCD) detectors. The relative 4 He and 5 He ternary fission yields were determined. The kinetic energies of the 5 He and 4 He ternary particles were found to be approximately 11 and 16 MeV, respectively. The 5 He particles contribute 10-20 % to the total observed alpha ternary yield. The data indicate that in nuclei with octupole deformations the population for the negative parity bands might be enhanced in the α ternary fission. >From LCP-γ double gated spectra, neutron multiplicity distributions for α ternary fission pairs were measured. The average neutron multiplicity decreases about 0.7 AMU in going from the binary to α ternary fission in the approximately same mass splittings (104-146). From the analysis of the γ-γ matrix gated on the 10 Be particles, the two fragment pairs of 138 Xe - 104 Zr and 106 Mo - 136 Te with no neutrons emitted are among the most strongly populated pairs. The first LCP - γ data indicate that the cold (neutronless) process could be more dominant in ternary spontaneous fission, SF, with the third particle being 10 Be with the high kinetic energy. The most favored cases of cold 10 Be ternary SF processes are the deformed and spherical fragment pairs. (authors)