DETERMINATION OF ANGULAR DISTRIBUTIONS OF FISSION FRAGMENTS FROM ISOLATED MASSES BY SEMICONDUCTOR GAMMA-SPECTROMETRY

There are now various theories regarding the mechanism by which fission fragment mass distributions are formed. The existence of two fission modes is attributed to the difference in the barrier heights for symmetric and asymmetric fission modes in [I]. Comparison of the fragment mass yields from symmetric and asymmetric fission of actinide nuclei by a-particles with different energies has shown [2, 3] that the results are consistent with the hypothesis of different barriers for these fission modes [2, 3]. At the same time, the measurements of angular anisotropy as a function of fission asymmetry described in [4-6] revealed that there was no difference in anisotropy for symmetric and asymmetric fragments (within the limits of experimental error). This leads to the conclusion that the barriers are identical for the two fission modes. A difference in the angular distributions for symmetric and asymmetric fragments was demonstrated in [7-9]. Published experimental results thus do not permit us to draw an unambiguous conclusion regarding fission fragment mass distribution formation mechanism until the question of whether the angular distributions of fission fragments with different masses have the same or different anisotropy is conclusively resolved.