DEFORMATION PATHS OF A NUCLEUS IN FISSION

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Two kinds of kinetic energy components were discovered present for the fission producing fission fragments of A=126-134 in proton induced fission of ^<232>th.In the present work, the incident energy dependence of the intensity of each of those two components was studied for proton-induced fission of ^<232>Th and ^<238>U by varying the proton energy from 12 to 16 MeV.The kinetic energies were carefully measured by the double TOF method. The time calibration of the time-of-flight system was performed using the 240 MeV ^<127>I beam from a tandem accelerator.The results clearly indicated that the intensity of the low kinetic energy component has the incident energy dependence similar to the mass yields of symmetric-mass-division products have while the intensity of high kinetic energy component behaves similarly to the yields of asymmetric-mass-division products.They lead to the conclusion that two deformation paths indeed exist in the low energy fission of light actinide : "one path experiences a higher fission barrier and ends up in symmetric mass division with the more elongated scission configuration, and the other goes over a lower fission barrier and leads to asymmetric mass division with more compact scission configuration.Those two deformation paths co-exist in the fission which produce fragments mass of 126 to 134.