Biennial Report 2005-2007 - Saha Institute of Nuclear Physics

2 Nuclear SciencesDuring this period most of the work carried out under the Nuclear Sciences utilized thein-house facilities developed over the couple of years and the accelerator facilities of thecountry. Members of the group also participated in a number of experiments involvinginternational collaboration. The INGA facilities installed at VECC and the 20Ne beamfrom VECC were extensively utilized to study structure properties of nuclei in differentmass regions and interesting results have been obtained. Different phenomenologicalmodels have been employed to explore the dynamics of nuclear structure and reactionin several cases. A significant amount of work was initiated for the simulation of differenttype of nuclear detectors. For this purpose, a “nearly exact Boundary Element Method(neBEM)” solver was developed. In the field of Atomic Physics, a clear signature ofmultiple ionization on L subshell ionization of Gold and Uranium has been obtained fromthe heavy-ion induced reaction. Lifetimes of several levels of singly ionized KrII, XeIIand ArII have been measured for the first time utilizing the in-house facilities. In thedomain of Applied Nuclear Sciences the study of defects and morphological features ofdifferent nanostructures as revealed from positron annihilation studies was undertaken.In addition, this group continued the study of irradiation induced defects in differentmaterials and their temperature evolution. The perturbed angular correlation (PAC)studies have been performed in Hf-Zr alloy. Developmental work related to differentdetector systems have been undertaken.2.1 Nuclear Scattering and Reactions2.1.1 Experimental Studies2.1.1.1 Indirect measurement of 14 C(n,γ) 15 C capture cross-section in AstrophysicalscenariosRadiative capture cross sections play significant role in many cosmic phenomena, i.e, galactic evolution,star formation and planet formation etc. A number of indirect methods are being exploredby experimental nuclear physicists to avoid radioactive targets and other difficulties of direct measurementsof radiative capture cross sections. Coulomb dissociation (CD) of radioactive ion beamsat intermediate energy is one of the most powerful indirect methods for measuring capture crosssection. To establish the indirect measurement of neutron capture cross sections in astrophysicalscenarios it is more essential because a neutron target is not available and targets of short-livedunstable nuclei are also not possible. We have shown for the first time that the CD method isalso very successful in measuring neutron capture cross sections by using of 14 C(n,γ) 15 C reactionand the measured cross-section is in agreement with direct measurement which has been repeated37