Four Channels in the Fission of ²⁵²Cf

Abstract

Strutinsky-type calculations indicate that the potential energy favors four channels in the nuclear fission o f 252Cf. The connection o f this finding with experimental results on the dis tribution of fragment mass, total kinetic energy, neutron multiplicities, and relative abundances is discussed. Similar calculations for 227Ac, 236U, and 258Fm show that the changing preponder ance of the four channels seems to describe striking trends in the fission o f the actinides, in particular the dip in the total kinetic energy at symmetrical fission of 236U and the enormously high average kinetic energy of the 258Fm fragments.

Photon and proton induced fission on heavy nuclei at intermediate energies

“…Whenever fission occurs, the fragments are determined according to the relative intensities of each fission mode, namely Superlong (SL), Standard I and Standard II, respectively, one symmetric and two asymmetric channels. The Random Neck Rupture Model (MM-NRM) [20] has successfully described the fission process by taking into account the collective effects of nuclear deformation during fission with the liquid-drop model, and single-particle effects through microscopic shell-model corrections. The microscopic corrections create valleys in the space of elongation and mass number, each valley corresponding to one different fission mode.…”

Superasymmetric fission of heavy nuclei induced by intermediate-energy protons

“…If the nucleus undergoes fission, the production of fragments is determined according to the multimodal-random neck rupture model (MM-NRM) [29], which takes into account the collective effects of nuclear deformation during fission by the liquid-drop model and single-particle effects by microscopic shell-model corrections. The microscopic corrections create valleys in the space of elongation and mass number, where each valley corresponds to a different fission mode [29].…”

15 Fission Fragment Mass, Charge and Energy Distributions

“…In consequence, predicted yields on the wings can be wrong by orders of magnitude. An attempt to understand the large width of the mass distribution curves observed by introducing fluid dynamics has been made recently by Brösa [51][52][53]. Indeed, this model enables the width parameter of mass distribution curves to be understood in a way that no other model could explain so far.…”

“…20) increases with the increase of Ek from mass 158 to mass 130. Between mass 129 to 118 a peak-like structure is found that has been attributed [117] to the mixing of three exit channels of different kinetic energy in the model of Brösa et al [51][52][53], It is, however, probably affected by some more narrow fine structures found in the width of the energy distribution of single fragments by other authors for 235 U and 233 U [118], 242m + 8 Am [119] and 249 Cf [45], Monte Carlo calculations have led to the result that a fine structure in the width parameter is to be expected due to the high number of prompt neutrons emitted from fragments on the inner (heavy) side of the light mass peak that leads to a mixing of various primary fragment masses possessing initially quite different kinetic energies because in this mass range kinetic energy changes rapidly with mass. Another fine structure seen by Belhafaf et al [118] in the fission of Proton odd-even effect as a function of the difference in kinetic energy of even-and odd-Z elements (energy odd-even effect) for various thermal neutron induced fission reactions of even Ζ isotopes (elements are indicated besides the data points).…”