Photography revealed cosmic rays in physicist’s work

In the 1930s, physicist Bibha Chowdhuri used photography to detect and study invisible cosmic radiation in India.

Working with DM Bose at the Bose Institute in Calcutta, Chowdhuri placed photographic plates at high altitudes, including Sandakphu, to capture traces of nuclear disintegration caused by cosmic rays. These plates, prepared with samarium sulphate, revealed “star-like tracks” representing the paths of subatomic particles. Chowdhuri’s experiments built on the work of Marietta Blau, who pioneered using photographic emulsions to detect subatomic events.

Chowdhuri and Bose developed methods to distinguish between particles by the patterns they left on the plates, contributing to research that eventually led to Cecil Powell’s Nobel Prize. Their 1939 article detailed this new method of using photographic plates to extend exposure times and capture rare nuclear events. Despite facing challenges obtaining materials during World War II, Chowdhuri continued her research, later pursuing a PhD at the University of Manchester and working at the Tata Institute of Fundamental Research.

She eventually shifted to neon flash-tube techniques, but her early work established photographic methods as a crucial tool for visualizing the invisible world of particle physics.