Journey of an experimental cosmic ray physicist

I would describe my journey as an experimental cosmic ray physicist in TIFR starting from summer of 1976. I have been fortunate that I always was able to work on experiment from the start, and got to develop state-of-the-art detectors, electronics and write programs for data analysis. This journey became a real adventure as we had to solve every problem in-house with little or no infrastructure backup. Along the way we developed civil, mechanical and electrical infrastructure for the laboratory. The members of Cosmic Ray Laboratory in Ooty acquired a wide range of advanced skills through sheer hard work and dedication. This culminated in the development of world-class plastic scintillators, and large sealed proportional counters and a host of other devices. The DAE/DST 2020 Vision document in 2006 accorded the highest priority of the GRAPES-3 in astroparticle physics. Our work was also appreciated by an International Panel of eminent scientist that reviewed the DHEP in 2008 in the following quote,

“The work is based on the application of meticulous state-of-the-art methods, and is performed with great enthusiasm by the participating staff members, with excellent guidance provided by the faculty responsible for the activity.”

Thunderstorms have fascinated humans from the dawn of civilisation because of their spectacular appearance and devastating consequences. Yet it surprising that very little is known about their physical properties. In 2014, the GRAPES-3 muon telescope detected a spectacular thunderstorm and we could determine several of its physical properties for the first time. This included the measurement of a voltage of 1.3 GV across the thunderstorm which validated the 90-year-old prediction of Nobel laureate Prof. C.T.R. Wilson. This study revealed that thunderstorms are at least 10 times more powerful than previously known.

About the Speaker:

Prof. Sunil Gupta joined Tata Institute of Fundamental Research, Mumbai in August 1976 and retired as Senior Professor in 2020. Honoured with prestigious Dr. Raja Ramanna Fellowship to work in TIFR and BARC from December 2021 onwards. He carried out research in international centres including the University of Maryland, Fermi-Lab near Chicago, Los Alamos Lab, and NASA/GSFC in USA. Also worked at CERN, Geneva Switzerland, RWTH Aachen Germany, INFN Pisa Italy, Osaka City University, Chubu University, Nagoya University and Tokyo University in Japan in high energy physics and astrophysics. Over the last three decades he led the setting up of GRAPES-3 experiment at Ooty the largest astroparticle facility in India and developed many new instruments with applications in atomic energy and space sciences. Involved more than 30 Indian and Japanese scientists to work on the GRAPES-3.

Prof. Gupta was honoured with memberships, Chairpersonships and Professorships of many national and international bodies, which include Astronomical Society of India, International Astronomical Union (IAU), Paris, National Academy of Sciences of India, Allahabad, Commission C4 on Astroparticle Physics of IUPAP, International Emulsion Chamber Committee, VIIT, Pune, Chubu University, Japan. He was invited by Nobel Committee for Physics to submit nominations for the award of the Nobel Prize in Physics in the previous decade. He also served as the Chair of the International Advisory Committee of three of the most prestigious conferences in the field of Astroparticle Physics. He delivered invited lectures all over the world in Asia, Europe, Russia, USA, Canada, South America and is frequently invited as speaker at national and international level.

In 2016, Prof. Gupta led the GRAPES-3 in the discovery of “transient weakening of Earth's protective magnetic field” during a solar storm and in 2019 the discovery that thunderstorms produce a voltage of more than one billion volts and possess enough energy to power a city like Mumbai for one hour. He has over 250 publications in scientific journals, proceedings of national and international conferences, symposia and workshops.