Abstract :

Since the very early days of discovery of radioactivity in atomic nuclei, the neutrino has played a vital role. In particular, the neutrino: an evasive, electrically neutral, spin 1/2 particle, initially assumed to be massless, led to the understanding of the beta decay, weak interaction process which violates parity. Today, the neutrino has opened up fresh avenues beyond the standard model of particles physics. Over the last decade or so, studies on the atmospheric and solar neutrino oscillation data, have established that neutrinos have a very tiny mass. This leads us to one of the key questions, namely, whether the neutrino has a distinct antiparticle (Dirac) or is its own antiparticle (Majorana)? The nuclear double beta decay is very rare, second order weak interaction process and occurs when single beta decay is forbidden. Both, the nuclear beta decay and double beta decay can provide the information on the mass of the neutrinos. At present, neutrino-less double beta decay is perhaps the only experiment that can tell us whether the neutrino is a Dirac or a Majorana particle. Given the significance of the 0nu2beta, there is a widespread interest for these rare event studies employing a variety of novel techniques. This talk will briefly review the current experiments and present some of the future proposals expected to achieve very high sensitivity. With the upcoming INO underground laboratory in India, a multi-institutional effort to carry out an underground neutrino-less double beta decay (0nu2beta) experiment was initiated. A crucial criterion for detector design is high energy resolution for a precision measurement of the sum energy of two electrons emitted in 0nu2beta decay. The low temperature bolometric detectors are ideally suited for this purpose. It was decided to focus on the feasibility of a Sn cryogenic bolometric detector operating at 10 mK, for the study of 0nu2beta in 124Sn. The preliminary R&D efforts for this experiment are being done at TIFR and the setup comprising a cryogen-free, high capacity, 3He−4He dilution refrigerator. The experiment is highly interdisciplinary spanning nuclear and particle physics and condensed matter physics, and requires an expertise in a variety of techniques and tools, such ultra-low temperature, metallurgy and material science, isotope separation, semi-conducting materials and device fabrication, digital signal processing, etc. This talk will highlight the challenges in the R&D efforts towards the development of the cryogenic Sn bolometer for the study of 0nu2beta in 124Sn.

ABOUT THE SPEAKER:

Prof. R.G. Pillay is a Senior Professor in the Department of Nuclear & Atomic Physics at the Tata Institute of Fundamental Research, Mumbai. Prof. Pillay completed his B.Sc and M.Sc in Physics from IIT, Kharagpur and IIT, Kanpur, respectively. He then joined TIFR for his PhD and has been faculty since 1977. He also performed post-doctoral work at SUNY, Stony Brook, US. He has diverse research interests in nuclear, accelerator and condensed matter physics. Aside from spearheading the search for 0nu2beta decay in India, he has developed the first super-conducting accelerator in India: the Heavy Ion Superconducting Linac Booster. In addition, he is steering several future projects including serving on the Project Advisory Committee of the future International Linear Collider. In addtiona, he is the National Coordinator of the Ganil Spiral2 project, Caen, France and Nuclear Structure for India-GSI FAIR project at Darmstadt, Germany.