Biennial Report 2005-2007 - Saha Institute of Nuclear Physics

Nuclear Sciences 412.1.1.10 The study of threshold behaviour of effective potential for 6 Li+ 58,64 NiThe elastic scattering for 6 Li+ 64 Ni system was measured in the bombarding energy range of 13 MeV≤ E lab ≤ 26 MeV. A phenomenological optical model analysis was performed and the behaviourof the surface strengths of the potential components with decreasing energy was extracted. Afurther analysis of the measured angular distributions, along with the existing data for 6 Li+ 58 Ni,was performed with two different model potentials - one with the folded potential normalized witha complex factor and the other with a hybrid potential composed of a renormalized folded realand a phenomenological imaginary potential components. All the model potentials predict similarenergy dependent behaviour for the interaction potential around the barrier. The observed energydependence of the strengths of the real and imaginary potentials corroborate with the dispersionrelation prediction for both the 6 Li+ 64 Ni and 6 Li+ 58 Ni systems. Though the evidence of breakupis distinct in the energy variation of the potential strengths, close to the barrier the variation ismore in the line of conventional threshold anomaly. Also the threshold behaviour of the interactionpotential does not indicate any distinct isotopic dependence.M Biswas, Subinit Roy, M Sinha, MK Pradhan, A Mukherjee, P Basu, H Majumdar, K Ramachandran†,A Shrivastava†NAP2.1.2 Phenomenology2.1.2.1 Unified description for the nuclear equation of state and radioactivityA mean field calculation for obtaining the equation of state (EOS) of nuclear matter from a densitydependent M3Y interaction (DDM3Y) is performed. The energy per nucleon is minimized toobtain ground state of the symmetric nuclear matter (SNM). The constants of density dependenceof the effective interaction are obtained by reproducing the saturation energy per nucleon andthe saturation density of SNM. The EOS of SNM, thus obtained, provides excellent estimate ofnuclear incompressibility. The microscopic proton-nucleus and alpha-nucleus interaction potentialsare obtained by single folding the density of the daughter nucleus and double folding the densitiesof alpha and the daughter nuclei, respectively, with DDM3Y effective interaction whose densitydependence is determined from nuclear matter calculations. The quantum mechanical tunnelingprobability is calculated within the WKB approximation using these nuclear potentials. Thesecalculations provide reasonable estimates for the observed proton radioactivity lifetimes, alphadecay lifetimes including those of new superheavy elements like 112, 114, 116, 294 118 etc. TheEOS for asymmetric nuclear matter is calculated by adding to the isoscalar part, the isovectorcomponent of M3Y interaction. The SNM and pure neutron matter EOS are used to calculatethe nuclear symmetry energy which is consistent with that extracted from the isospin diffusionin heavy-ion collisions at intermediate energies. Thus, the present calculations using a densitydependent effective interaction provide a unified description of radioactivity and nuclear matter.P Roy Chowdhury, C Samanta, DN Basu†NAP2.1.2.2 Radius and density in neutron rich He nucleiRelativistic mean field approach is a standard tool in low energy nuclear structure studies. Recently,a new Lagrangian density and parameter set, known as FSUGold, has been proposed for the RMF