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Variable Energy Cyclotron Centre, Kolkata
Posted by: Deepak Pandit & Tilak Ghosh on 17th August, 2015
Balaram Dey successfully defended his PhD thesis on last Tuesday, 11th August, 2015 at the N.K. Ganguly lecture hall. He is the first student of the VECC pre-doc batch 2010 to complete his thesis work.
In his thesis work, Balaram studied the temperature dependence of giant dipole resonance (GDR) width at excited states of atomic nuclei in the mass ~100 region at low temperature.
Giant resonance is a collective mode of excitation of nuclei and originates because of the out of phase collective oscillations of neutron and protons in nuclei. The resonance is called “giant” because the wide maximum in the reaction cross section associated with the resonance indicates that essentially all nucleons participate in the process. Study of GDR are of particular interest as they provide the most reliable information about the bulk behavior (e.g; viscosity) of the nuclear many-body system. Although, GDR had been studied for a long time, the temperature dependence of this resonance is still not understood completely due to lack of experimental data, particularly at the low temperature.
[Photograph taken during our group picnic in winter, Balaram (seen with wearing full sleeves sweater) has a great admiration for all kinds of sports activities in the campus, particularly in cricket !]
Balaram, along with his group members under the supervision of Sudhee Ranjan Banerjee, carried out extensive experimental study to provide new data of the GDR width at low temperature for the nuclei 97Tc. Indeed, he presented the first data points at low temperature in this mass region and compared the data with different theoretical models and showed that the experimental findings are consistent with the critical temperature fluctuation model that was recently proposed by researchers at VECC. He found that the measured data are consistent with the phonon damping model too but differs significantly from the commonly accepted thermal shape fluctuation model. These interesting results indicated that the effect of GDR induced deformation could be one of the ways in explaining macroscopically the behavior of GDR width at low temperature.
Congratulations Dr. Balram Dey, wish you all the best for a fascinating career ahead!