PARITY VIOLATION IN TERNARY FISSION

The parity-violating correlation between incoming neutron spin and fra gment momentum has been measured simultaneously for binary and ternary fission of U-233(n, f) and Pu-239(n, f). The experiment has been perf ormed with a polarized cold neutron beam of the Institut Laue-Langevin in Grenoble/France. The ratios of the parity-violating asymmetry coef ficients, alpha(nf)(ter) and alpha(nf)(bin), for ternary and binary fi ssion, respectively, are found to be alpha(nf)(ter)/alpha(nf)(bin) = 1 .05+/-0.10 and 1.12+/-0.08 for the U-233 and Pu-239 target nucleus, re spectively. Both experiments are compatible with alpha(nf)(ter)/alpha( nf)(bin) = 1. The implications of this result for models of ternary fi ssion are discussed. The conclusion drawn is that ternary particles ar e emitted at the very last stage of fission.