Biennial Report 2005-2007 - Saha Institute of Nuclear Physics

Nuclear Sciences 45ray spectroscopy.U Datta Pramanik, Somnath Chakraborty†, Rajendra Giri†, I Ray, Sujib ChatterjeeNAP2.2.1.6 Gamma spectroscopy in A ∼ 40 region(1) An experiment was performed with the array of eight Clover detectors (Indian National GammaArray or INGA) at Variable Energy Cyclotron Centre (VECC), Kolkata. Moderate spin states of34,35,36,37 Cl and other nuclei in A∼ 40 have been populated using 27 Al( 16 O,xαynzpγ) at a projectileenergy of 115 MeV. (2)An experiment was performed using an array of 7 Compton suppressed Cloverdetectors placed in a horizontal plane at TIFR, Mumbai. The reaction was 27 Al( 14 N,xαynzpγ) ata projectile energy of 66 MeV.The aim of the experiment was to investigate the structure of nucleiin the sd-fp interface with a special focus on the estimation of level lifetimes using Doppler Shiftattenuation technique.Ritesh Kshetri, R Raut, S Ganguly, MK Pradhan, D Kanjilal, M Saha Sarkar, Indrani Roy,Moumita Ray Basu†, Gautam De†, Krishichayan†, A Chakraborty†, M Ray†, A Goswami, P Banerjee,A Mukherjee, U Datta Pramanik, SS Ghugre†, S Bhattacharya, B Dasmahapatra, S Sarkar†,R Palit†, HC Jain†, I Mazumdar†, A Deo†, S Kumar†NAP2.2.1.7 Gamma spectroscopy in A ∼ 160-170 regionHigh-spin states in 169 Ta have been populated through 159 Tb( 16 O,6nγ) reaction at a projectileenergy of 115 MeV. The γ − γ coincidence measurement has been done using the INGA setupat VECC, Kolkata. A number of nuclei like 167,168 Lu, 168−170 Hf, 169−171 Ta were populated. Thelifetimes of the isomeric levels of these nuclei have been re-measured using the centroid shift methodof electronic timing technique. Preliminary results are in good agreement with the adopted valuesfor 169,171 Ta. Theoretical calculations using the Particle-Rotor Model have been done. The resultsshow very good agreement with the experimental data.Ritesh Kshetri, Indrani Roy, Moumita Ray Basu†, Gautam De†, S Ganguly, MK Pradhan, RRaut, Krishichayan†, A Chakraborty†, M Ray†, A Goswami, P Banerjee, A Mukherjee, U DattaPramanik, SS Ghugre†, S Bhattacharya, B Dasmahapatra, S Sarkar†, M Saha Sarkar NAP2.2.1.8 Spectroscopy of few-valence particle nuclei around 146 Gd CoreHigh-spin states in 153 Ho have been populated through 13957 La(20 Ne,6nγ) reaction at a projectileenergy of 139 MeV. The γ -γ coincidence measurement has been done using the INGA setup atVECC, Kolkata. A number of nuclei like 153,152 Ho, 145 Eu, 151−153 Dy were populated. 153 Ho hasbeen populated most strongly. States up to previously reported 77/2 + are observed in the presentexperiment . The theoretical studies within Particle Rotor Model indicate a shape coexistence init. For lower spins the nucleus is prolate, which changes to an oblate structure at higher spins.Gautam Dey†, A Chakraborty†, Krishichayan†, Ritesh Kshetri, I Ray, S Ganguly, MK Pradhan, RRaut, Moumita Ray Basu†, M Ray†, G Ganguly†, SS Ghugre†, AK Sinha†, SK Basu†, A Goswami,P Banerjee, A Mukherjee, S Bhattacharya, M Saha Sarkar, S Sarkar†NAP