Biennial Report 2005-2007 - Saha Institute of Nuclear Physics

Nuclear Sciences 43at high angular momentum that is usually ignored in the evaporation formalism. A common prescriptionis to modify the moment of inertia in terms of two arbitrary parameters. In order to avoidthis arbitrariness, we instead modify the mass at high angular momentum in terms of the rotatingliquid drop model. The shortcoming in the calculated spectra can be satisfactorily removed in thismethod.Chinmay BasuNAP2.2 Nuclear Spectroscopy & Structure2.2.1 Experimental Studies2.2.1.1 Study of the nuclei around A∼120 near proton-drip line at (IUAC), NewDelhiOne of the most exciting subjects in contemporary nuclear physics is the study of nuclei at thelimits of stability. Using stable beam, through fusion evaporation reaction, it is possible to studynuclei near proton-drip line. The main aim of this project is to understand the role of np residualinteraction near proton drip line. For this purpose, high spin states of very neutron-deficient nuclei118 Xe(S p =4.6 MeV), 120 Cs(S p =2.5 MeV), 121 Ba(S p =3.7 MeV) and 121 La(S p = 0.8 MeV) (wherevalence protons are loosely bound) were populated through fusion evaporation reaction 92 Mo( 32 S,xpyn). The 32 S beam at an energy of 140 MeV was obtained from 15UD Pelletron machine at NSC,New Delhi. The de-excited gamma-rays of the populated nuclei were detected in coincidence mode(γ − γ − t) with GDA (gamma detector array). The data analysis shows that the channels withmajor cross-sections are in agreement with PACE and CASCADE prediction with 10 MeV lowerbeam energy. Detail analysis is in progress.U Datta Pramanik, I Ray, S Basu†, S Bhattacharya, R Bhowmik†, R Kshetri, R Kumar†, AMukherjee, S Mandal†, S Muralithar†, Ranjeet†, M Saha Sarkar, RP Singh†NAP2.2.1.2 Structure of the Ge and Zn neutron-rich nuclei around N=50 using Clara-Prisma array at LNL, INFN, ItalyDoubly-magic nuclei located in very exotic region of the nuclear chart are key elements in thepresent day nuclear-structure studies. The appearance or disappearance of shell gaps associatedto “magic” character allows the determination of the single-particle energies and of the residualinteractions between valence nucleons. Particularly, isotones of the N=50 shell are interesting wherea systematic drop of the excitation energy of the 2 + states has been taken as an indication of theonset of shell-gap quenching. A eleven days experiment were performed using the ( 82 Se + 238 U)deep-inelastic and multi-nucleon transfer reaction at 515 MeV of beam energy, at the CLARA-PRISMA setup to populate the excited states in neutron-rich nuclei Ge, Ga and Zn isotopes withN=50. The analysis seems to indicate the existence of still sizable N=50 gap close to 78 Ni.T Faul†, G Duchen†, G de Angelis†, N Marginean†, F Nowacki†, E Sahin†, A Algora†, S Aydin†, FAzaiez†, G Beghini†, G Benzoni†, M Bostan†, A Brondi†, T Byrski†, I Celikovic†, R Chapman†, LCorradi†, S Courtin†, D Curien†, U Datta Pramanik, F Della Vedova†, O Dorvaux†, N Erduran†,S Erturk†, E Farnea†, E Fioretto†, G De France†, S Franchoo†, A Gadea†, et al NAP