Neutrinoless double beta decay (0íââ) is the only known process which can shed light on the Majorana nature of the neutrinos. It also enables us to experimentally test the absolute mass scale of the (Majorana) neutrinos, thereby providing one of the most sensitive tests for physics beyond the Standard Model. There are several experiments worldwide to study 0íââ in different nuclei. Én India, efforts have been initiated for experiment to look for 0íââ in 124Sn (Qââ=2.28 MeV, 5.8% abundance) at the underground facility of India Based Neutrino Observatory (INO).
The identification of 0íââ necessarily relies on measurement of the sum energy (= Qââ) of the two emitted electrons and requires a high resolution detector to detect the 0íââ process in the presence of more probable 2íââ process. Cryogenic Bolometer detectors with their excellent resolution are good for observation of this rare process. Moreover since it¢s a calorimetric measurement, active source method (i.e. detector itself is a source) can be used, which will result in better sensitivity. The Sn becomes superconducting at 3.7K and its specific heat drops off exponentially at lower temperatures. It has mainly lattice contributions at tens of mili-kelvin and this enables use of Sn as a bolometer. Furthermore, extremely low rates of the 0íââ demand a large mass and an exceptionally low radioactive background (hence underground laboratory).
I will talk about the efforts undertaken to make a small prototype of superconducting bolometer of natural Sn and to study the feasibility of upgrading it to large scale experiment. It will mainly focus on the physics issues related to the fabrication of the Sn cryogenic bolometer.