Role of Shell-Closures and Deformations in Fission Mass Distribution of Actinides

Abstract The present work identifies the fission fragments operating in even-even actinides within the framework of Quantum Mechanical Fragmentation Theory (QMFT). The fragmentation potential is worked out through the incorporation of spherical, quadrupole, and octupole deformed elongated configurations of the probable binary fragments. The shell-closures, binding energies, and deformations emphasize the potential energy minima, and subsequently the preformed cluster probabilities illustrate the fragment distributions in the spontaneous fission channel. The mass-yield distributions, calculated either using the collective clusterization method, or the BSM approach, or where the available experimental data for actinides with \(98\leq Z\leq102\) and \(150\leq N\leq164\), exhibit the single- and double-hump structures, as they are mutually associated with the fragmentation near \ 132 Sn (spherical shape) and \144\Ba (pear-shaped), respectively. Therefore, based on this, we have examined about 150 cases of even-even actinides, belonging to \(90\leq Z \leq102\) and \(108\leq N \leq166\) regions. The study reveals a systematic evolution in fission mass distributions: beginning with near-symmetric splits driven by partial shell closures in quadrupole-deformed fragments, progressing to pronounced asymmetry governed by large shell gaps at the deformed magic numbers (\(Z_{\mathrm{HF}}\approx56\) and \(N_{\mathrm{HF}}\approx88\)) of heavy-mass fragments, and ultimately returning to symmetric patterns stabilized by the double magic configuration (\(Z_i\approx50\) and \(N_i\approx82\)) for binary fragments.