Kolkata, India. Scientist Bibha Chowdhuri, along with director Debendra Mohan Bose of the Bose Institute, experimentally observed and published reports on showers of mesotrons, later called mesons. She studied batches of Ilford halftone plates exposed to cosmic rays at two different altitudes, one in Darjeeling and a higher one in Sandakphu. The particles had decreased mass at lower altitudes, suggesting they had decayed over time. She noted that the decays were curved, likely due to multiple scattering of the particles. They were unable to pursue the investigation further because more sensitive emulsion plates were unavailable. In England in 1947, Cecil Powell and Giuseppe Occhialini used the same method, but with better emulsions, to demonstrate the existence of the pion.
