ANGULAR ANISOTROPY OF FISSION FRAGMENTS IN TERNARY FISSION OF 235U INDUCED BY 3 MEV NEUTRONS

The values of angular anisotropy of fragments in binary and ternary fission of 235U induced by 3 MeV neutrons have been determined with two independent methods. In the first method fission fragments and long range alpha particles were detected with a gridded ionization chamber and a CSI crystal respectively and in the second method semi-conductor detectors were used to detect fission fragments and long-range alpha particles. The values of N(0°)/N(90°) for cases of binary and ternary fissions are found to be different. The probability for emission of long range alpha particles in 3 MeV neutron induced fission is found to be lower than that in thermal neutron induced fission. A decrease in the average single fragment kinetic energy of ternary fragments compared to that of binary fragments is observed in 3 MeV neutron induced fission similar to that in thermal neutron fission. It is shown that on the basis of the angular distribution of long range alpha particles and ternary fragments it is possible to learn at what stage in the fission process the long range alpha particles are emitted. © 1968.