[en] A simple superasymmetric fission model using microscopically calculated nuclear potentials has shown itself to be outstandingly successful in describing highly asymmetric spontaneous disintegration of nuclei into two composite nuclear fragments. The nuclear interaction potentials required to describe these nuclear decay processes have been calculated by double folding the density distribution functions of the two fragments with a realistic effective interaction. The microscopic nucleus-nucleus potential thus obtained, along with the Coulomb interaction potential and the minimum centrifugal barrier required for the spin-parity conservation, has been used successfully for the lifetime calculations of these nuclear disintegration processes

[en] Coulomb dissociation of ⁶Li in the field of ²⁰⁸Pb at different energies via resonance and continuum levels is discussed in detail. Relations are given which can be used to directly relate the Coulomb break-up cross section to the astrophysical S-factor. Predictions for energy dependence and angular-distributions are given. The direct Coulomb break-up of ⁶Li is found to be of the same order of magnitude as the sequential break-up at higher projectile energies. The effect to eleastic scattering can be accounted for by introducing a dynamic polarization potential. Predictions are given for the direct Coulomb dissociation of 26 MeV/nucleon ⁷Li and ¹⁶O incident on ²⁰⁸Pb through dipole transitions to the continuum, and for ²⁰Ne via quadrupole transitions in similar experimental situations. (orig.)

[en] A mean field calculation for obtaining the equation of state (EOS) for nuclear matter from a density dependent M3Y interaction (DDM3Y) supplemented by a zero-range potential is performed. The energy per nucleon is minimized to obtain ground state of the symmetric nuclear matter (SNM). The constants of density dependence of the effective interaction are obtained by reproducing the saturation energy per nucleon and the saturation density of SNM. The EOS of SNM, thus obtained, provide reasonably good estimate of nuclear incompressibility. The microscopic proton-nucleus and α-nucleus interaction potentials are obtained by single folding the density of the daughter nucleus and double folding the densities of the α and the daughter nuclei, respectively, with DDM3Y effective interaction whose density dependence is determined from nuclear matter calculations. The quantum mechanical tunneling probability is calculated within the WKB approximation using these nuclear potentials. These calculations provide reasonable estimates for the observed proton radioactivity lifetimes and α decay lifetimes including those of new superheavy elements 112, 114, 116 and the element ²⁹⁴118 and of some decay products and of the consecutive α decay chains of the two isotopes ²⁸⁷115 and ²⁸⁸115. These potentials also provide good descriptions for elastic and inelastic scattering of protons from nuclei ¹⁸Ne, ¹⁸O etc. and the deformation parameters extracted from inelastic scattering are in agreement with those extracted from the reduced electric quadrupole transition rates. The EOS for asymmetric nuclear matter is calculated by adding to the isoscalar part, the isovector component of M3Y interaction. The SNM and pure neutron matter EOS are then used to calculate the nuclear symmetry energy which is consistent with that extracted from the isospin diffusion in heavy-ion collisions at intermediate energies. The calculated β equilibrium proton fraction forbids direct URCA process which is consistent with the fact that there are no strong indications that fast cooling occurs. (author)

[en] Published in summary form only

[en] Published in summary form only. 1 fig

[en] The aim of the present work is to obtain photofission cross section

[en] Photonuclear reactions at energies covering the giant dipole resonance (GDR) region are analyzed with an approach based on nuclear photoabsorption followed by the process of competition between light-particle evaporation and fission for the excited nucleus. The photoabsorption cross-section at energies covering the GDR region is contributed by both the Lorentz-type GDR cross-section and the quasi-deuteron cross-section. The evaporation-fission process of the compound nucleus is simulated in a Monte Carlo framework. Photofission reaction cross-sections are analyzed in a systematic manner in the energy range of ∝ 10-20 MeV for the actinides ²³²Th, ²³⁸U and ²³⁷Np. Photonuclear cross-sections for the medium-mass nuclei ⁶³Cu and ⁶⁴Zn, for which there are no fission events, are also presented. The study reproduces satisfactorily the available experimental data of photofission cross-sections at GDR energy region and the increasing trend of nuclear fissility with the fissility parameter Z²/A for the actinides. (orig.)

[en] The relations between the geometries of density distributions and potentials obtained by folding these with density dependent forces have been used to obtain empirical estimates of the range and the density dependence of effective proton-, deuteron-, helion-, and alpha-nucleon interactions, from best fit phenomenological optical potentials available in literature, for these projectiles. (orig.)

[en] The observed target mass dependence of the volume integral per interacting nucleon pair of the real optical model potential for deuterons, helium-3 and alpha particles is explained in terms of the density dependence of the effective projectile-nucleon interaction. A mass dependence function for light ions is derived, which for density dependent forces consists of a volume, a surface, a curvature, and a higher order correction term. For non-saturating forces, this has only the volume term and fails to account for the observed mass dependence. (orig.)

[en] The nuclear cluster radioactivities have been studied theoretically in the framework of a microscopic superasymmetric fission model (MSAFM). The nuclear interaction potentials required for binary cold fission processes are calculated by folding in the density distribution functions of the two fragments with a realistic effective interaction. The microscopic nuclear potential thus obtained has been used to calculate the action integral within the WKB approximation. The calculated half-lives of the present MSAFM calculations are found to be in good agreement over a wide range of observed experimental data