Homi Bhabha and Cosmic Ray research in India

Abstract

Cosmic rays are very high energy particles arriving from the depths of space and incident on the earth’s atmosphere at all places and at all times. The energy of these particles extends over 12 decades from around 109 ev to 1021 ev and mercifully for the survival of life, the intensity falls by atleast 22 decades from about 100 particles/cm2/s to 1 particle/1000 km2 year. Cosmic ray research led to the discovery of many of the fundamental particles of nature in the 30’s, 40’s and 50’s of this century and ushered in the era of ‘elementary particle physics’ at man-made accelerators. Even 86 years after the discovery, the sources of these particles and the mechanism of acceleration continue to remain a mystery.