NEUTRINOS – A NEW WINDOW TO THE UNIVERSE

Abstract

Neutrinos, “the most tiny quantity of reality ever imaginedby a human being”, as quoted by its co-discovererFrederick Reines, never ceased to puzzle physicists.Wolfgang Pauli introduced neutrino in 1930 as a desperateremedy to save the “law of conservation of Energy”. It thentook twenty seven long years to find the first experimentalevidence for its existence. The reason for this long wait isits extreme reluctance to interact with matter. Neutrino canpass through the earth, the sun or other astrophysical objectswithout much interaction. They interact at the best onlyone time over one billion in the huge apparatus built to detectthem. This particular property of neutrino however turnsout to be a blessing in disguise as it opens up a new windowto look at the interior of sun and other astrophysical objects.Over the last several decades, dedicated neutrino experimentsaround the globe have looked for neutrinos from the sun, fromouter space, from interior of the earth and from man made activities.These experiments have answered many of the questions relatedto particle physics, astrophysics and even geophysics.India has a long tradition in neutrino physics. In fact, the firstever cosmic ray produced neutrino was detected in an experimentin the deep mines of Kolar Gold Fields in 1965. India is againplanning to setup an experiment called India-Based NeutrinoObservatory (INO) to study some of the properties of neutrinos.In this talk I will describe few of these experiments and theirfindings. I will also discuss the INO experiment and its physicspotential.