Correlated mass, energy, and angular distributions from bremsstrahlung-induced fission of ~(234)U and ~(232)Th in the energy region of the fission barrier

摘要

The bremstrahlung-induced fission of ~(234)U and ~(232)Th has been studied at the superconducting Darmstadt linear accelerator (S-DALINAC) in the excitation energy region close to the fission barrier. Fission-fragment mass and total kinetic energy (TKE) distributions from ~(234)U were studied for the first time in this energy region. The results have been analysed in terms of fission modes, and a dominant yield of the mass- asymmetric standard-2 mode was found in both nuclei. No strong dependence of the fission-mode weights on the excitation energy of the compound nucleus was found. Correlations among mass, TKE, and angular distributions have also been investigated. A correlation in the form of an increased anisotropy for far-asymmetric masses and low TKE were found in both fissioning systems. A possible interpretation of this correlation in terms of fission modes is discussed.