Parity violation in ternary fission

Abstract

The parity-violating correlation between incoming neutron spin and fragment momentum has been measured simultaneously for binary and ternary fission of 233U(n, f) and 239Pu(n, f). The experiment has been performed with a polarized cold neutron beam of the Institut Laue-Langevin in Grenoble/France. The ratios of the parity-violating asymmetry coefficients, α ter nf and α bin nf, for ternary and binary fission, respectively, are found to be α ter nf α bin nf = 1.05 ± 0.10 and 1.12 ± 0.08 for the 233U and 239Pu target nucleus, respectively. Both experiments are compatible with α ter nf α bin nf = 1 . The implications of this result for models of ternary fission are discussed. The conclusion drawn is that ternary particles are emitted at the very last stage of fission.