Effect Of Compact And Elongated Configurations On The Spontaneous And Induced Fission Of Fm Isotopes

The spontaneous fission (SF) analysis of even mass Fm242-260 isotopes is carried out using a preformed cluster model based on quantum mechanical fragmentation theory. The deformation effects are included up to the quadrupole (beta(2)) deformed nuclei with optimum orientations (theta(opt.)(i)) leading to hot-compact (side-to-side) and cold-elongated (tip-to-tip) configurations. The spherical and hot-compact deformed configurations of decay fragments result in the symmetric fragment mass distributions for Fm isotopes; however, the symmetric peak gets sharper with an increase in the neutron (N) number of the parent nucleus. In the case of cold orientations, a transition from two-peaked (asymmetric fission) to three-peaked (multimodal fission) mass distribution is observed with an increase in the mass number of Fm. The SF half-lives (T-1/2(SF)) are calculated using the neck-length parameter (Delta R) for Fm242-260 isotopes and compared with the experimental data. Besides this, the induced fission of Fm isotopes is studied within the dynamical cluster-decay model. The energy dependence of fission fragment mass distributions and the isotopic dependence is analyzed at energy range E* = 5-42 MeV. In addition, the role of temperature-dependent deformations in the fission dynamics is also explored.