(a) Basic Research:
One of the major aspects of today’s nuclear physics research is to look for the dynamical effect which inhibits the fusion cross section. These studies are important since it gives clue for picking up the right kind of target and projectile combination for the formation of super heavy elements (SHE).
A comprehensive study of fission fragment mass and angular distribution at near barrier energies was embarked on for heavy ion induced fission reactions experimentally, to have an insight of the dynamics of the fusion-fission reactions. The experiments were carried out with pulsed heavy ions from the accelerators (NSC Pelletron, New Delhi, TIFR Pelletron, Mumbai, VECC Cyclotron, Kolkata) available in India using the detectors developed indigenously in the laboratory and in collaboration with JINR, Russia at Dubna cyclotron.
For the first time, a direct evidence of orientation dependent quasi-fission reaction was established by us. A novel and powerful tool to look for the onset of a non-statistical reaction mechanism in heavy ion induced fission was unearthed.
We have an active research program to explore the role of entrance channel of fusion-fission dynamics and shell (quantum) effects in the fission process.
(b) Developmental work:
#Gas detector development:
After an intensive R and D efforts, few position sensitive Multi-Wire Proportional Counters (MWPC) were designed and fabricated indigenously. These large area detectors have been proficiently used in the in-beam experiments at the major accelerator facilities available in our country. The position resolution achieved with these detectors is better than 600 micron and time resolution better than 500 pico-second.
In our country, in next few years we will have accelerators (Super Conducting Cyclotron at Kolkata, LINACs at Mumbai and Delhi) providing intermediate energy heavy ion beams that may be used for frontline research in many challenging areas of nuclear physics. The development works that have been initiated is to fulfill the detector requirement for efficient utilization of these accelerator facilities. Fabrication of an unique hybrid detector, conceptually a combination of gas MWPC backed by segmented silicon strips, capable of providing excellent timing, position and energy resolution for heavy fragments is under way. Design and fabrication of a large array of charged particle and neutron detector is in progress.
[Ref: T.K.Ghosh et al ; Nucl. Instrum. Phys. Res. A 540, 285 (2005) ]
# Charged Particle Detector Array (CPDA) development:
Our research group is responsible for building a charged particle detector array to be installed in the upcoming K=500 super conducting cyclotron beam hall at our VECC campus.The array will be used for nuclear reaction studies at low and intermediate beam energies. Currently, we are working on the development of the forward part of the array, consisting of 24 Si-Si-CsI(Tl) telescopes, for identification of particles (up to Z=10) produced in intermediate energy nucleus-nucleus collision. Area of each Si detector is 5 cm x 5 cm with 3 mm pitch. I am a key member of the group that is working on the finalization of the mechanical design of the array.
The High Resolution Array (HiRA) is a similar type of detector array operational at the National Superconducting Cyclotron Laboratory, Michigan State University. I was awarded with the Indo-US science and Technology Fellowship award for the year 2009 to work with the HiRA group for hands on experience on large array of detectors. During my one year visit to NSCL, I worked on the experimental project "Evolution of Neutron Holes in N=28 Closed Shell". The experiment required an up-gradation of the existing HiRA setup.
As a part of our on-going superconducting utilization project, we have a plan to fabricate a large liquid scintillator based neutron detector that offers very high detection efficiency and direct measurement of neutron multiplicity. A proto type neutron detector of volume 500 liter is under production now. As a member of the team, I took part in finalizing the mechanical design of the proto type neutron detector.
(c) In international collaboration : (Muon Arm Project )
In CERN-India collaboration project, Saha Institute of Nuclear Physics (SINP) has taken the responsibility to build the second tracking station in forward muon spectrometer in A Large Hadron Collider Experiment (ALICE). The experiment will investigate the physics of strongly interacting matters at extreme energy densities where the formation of a new phase of matter, the quark gluon plasma (QGP) is expected to be formed. I was significantly involved in the in-house fabrication of the two prototypes of cathode pad chambers (CPC) of size 30 cm x 30 cm and 1meter x 1meter. All the detectors were designed and fabricated at SINP, Kolkata. The final version of the detector has been completed and is being installed now at CERN, Geneva.