THE PROBABILITY OF THE TRIPLE FISSION OF URANIUM-235 BY MONOENERGETIC NEUTRONS IN THE 0.06 TO 10 ev ENERGY RANGE

The triple fission, i.e., the fission of a nucleus into 2 heavy fragments and a long-range alpha particle, represents one of the several decay modes of the excited nucleus. Its probability differs from that of ordinary fission and therefore the dependence of the probability of this event on the neutron energy was determined in the 0.06- to 10-ev range by means of the time-of- flight method with a resolution of 3 mu sec/m on the linear accelerator of the I. V. Kurchatov Institute. A system consisting of 7 ionization chambers was used for recording the fission events. The results indicated thnt the dependence of the triple-fission probability on the energy varies, pointing to a correlation between the probability of the triple fission and the corresponding level widths of the ordinary fission. The experiments also revealed the fact that in addition to the triple fission, the (n, alpha )/sup 235/U reaction also emits alpha particles, as the result of neutron capture at levels possessing a relatively long life. This is in agreement with the available data on the emission of alpha particles by deformed nuclei (R. Nobles, Phys. Rev. 126: 1508 (1962)). (TTT)