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The GRAPES-3 observatory: A sensitive probe in high-energy astroparticle physics

TIme: 3:00 pm on October 4, 2019
Venue: SBS Room No 17
Speaker: Dr. Pravata Kumar Mohanty, High Energy Cosmic Ray Group, Tata Institute of Fundamental Research, Mumbai
Abstract: The GRAPES-3 is a major astroparticle physics observatory located in Ooty, Tamilnadu. It is designed to observe cosmic rays and gamma-rays in 1-10000 TeV energy range. It is a growing collaboration of 16 institutions within from India and Japan. The GRAPES-3 experiment is spread over an area of 25000 m^2 comprising of 400 scintillators to detect cosmic ray showers, and 4000 proportional counters to detect muons in them. In this talk, I will discuss two recent discoveries from the GRAPES-3 experiment; (1) a crack in the Earth's magnetic shield through a cosmic ray burst during a massive solar storm [1], and (2) measurement of a record 1.3 Gigavolt potential in a thunderstorm through muon imaging, proving a 90-year old prediction by Nobel Laureate C.T.R Wilson [2]. This will be followed by a discussion on the GRAPES-3's potential to make major advances in understanding some of the open problems in high energy astrophysics, including the origin, acceleration, and propagation of high energy cosmic rays through accurate measurement cosmic ray energy spectrum over the knee and discovering PeV gamma-ray sources.