On Ternary Fission Induced by Neutrons
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CLEI Experiment
On Ternary Fission Induced by Neutrons G. V. Danilyan* Institute for Theoretical and Experimental Physics, National Research Center Kurchatov Institute, Moscow, 117218 Russia Received December 25, 2018; revised December 25, 2018; accepted December 25, 2018
Abstract—Experiments on measuring the rotational effect of the 234 U fissile nucleus at the scission point showed that the fissile nucleus rotates as a right screw with respect to the longitudinally polarized neutron beam direction in the ternary fission of the 233 U target nucleus induced by polarized s-neutrons; in the binary fission of the same nuclei it rotates in the opposite direction. Moreover, it was found that ternary fission “prefers” the spin state of J = I + 1/2. This phenomenon cannot be explained within the existing concepts of ternary fission as one of the two “final” states after neck rupture. The same “parent” 234 U nucleus cannot rotate in opposite directions in the two different final states. It should be assumed that ternary fission is a special branch of descent from the saddle point to the point of neck rupture. It can also be assumed that this branch is formed at the saddle point in a configuration favorable for cluster formation. Why does it prefer the spin state of J = I + 1/2? This is an interesting question for further studies. DOI: 10.1134/S1063778819030050
Ternary fission was found in a nuclear emulsion in the form of an odd track originating around the middle of a “fat” track and going at an almost right angle with respect to it. The main, “fat,” track is caused by light and heavy fission fragments. A detailed study of this phenomenon revealed that the charged particle detected together with fission fragments is primarily a long-range alpha particle formed in the region between the two fragments at the time of rupture of the “neck” connecting the two future fragments. The Coulomb field of the fragments “focuses“ the alpha particle in the equatorial “plane”, but, since the charge of the heavy fragment exceeds the charge of the light one, the maximum of the alpha-particle angular distribution is slightly shifted toward the lightfragment momentum (at an angle of about 83◦ ).
principles, if we consider the saddle point as the initial state and the point of the neck rupture as the final state, all wave functions for the set of final states must be represented in the full wave function for the initial state. Therefore, configurations corresponding to particular final states of binary and ternary fission already exist at the saddle point. Recent experiments yielded contradictory data on correlations of outgoing-particle momenta with the spin of the fissile nucleus. This contradiction can only be explained by assuming that ternary and binary fission processes develop not at the point of neck rupture but in the corresponding configurations of the nuclei at the saddle point. In 2005, a collaboration of Petersburg Nuclear ¨ Physics Institute (PNPI) and University of Tubingen The probability for such an event, which is not carried our an in-depth rese
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