Bibha Chowdhuri

Bibha Chowdhuri was a particle physicist who searched for new particles in cosmic ray air showers - the interactions of astrophysical particles with the Earth’s atmosphere.

She pioneered the use of photographic plates to preserve images of these showers and search for undiscovered particles. With this technique, Bibha Chowdhuri discovered mesons for the first time, though they could not obtain plates sensitive enough for a definitive mass measurement, due to WWII embargos.

Bibha Chowdhuri was born in Kolkata, India in 1913. She completed her BSc at the Scottish Church College in Kolkata. She continued to do a MSc in Physics from the University of Calcutta in 1936 and then went to work for Dr. Debendra Mohan Bose in 1939, with whom she conducted experiments at high altitudes in the Himalayas, which would lead to the early discovery of the meson.

She moved to the University of Manchester to complete her PhD under the supervision of Sir Patrick Blackett (who would later win the 1948 Nobel Prize winner for the development and applications of the Wilson cloud chamber). Bibha Chowdhuri’s PhD thesis work continued to focus on extensive air showers from cosmic rays.

After completing her PhD, Bibha Chowdhuri returned to India to work at the Tata Institute of Fundamental Research, where she was a key contributor to the discovery of the K meson. She continued this work at the Centre National de la Recherche Scientifique in Paris, the University of Michigan, and eventually moved back to India to work at the Saha Institute of Nuclear Physics.

Bibha Chowdhuri discovered the meson for the first time, which is a hadronic particle (composed of 2+ quarks) composed of an equal number of quarks and antiquarks. Since all mesons are unstable, living at most for ~tenths of a nanosecond, using imaging techniques is crucial, rather than the typical cloud chambers or bubble chambers used for particle identification at the time.

Cosmic rays constantly bombard the Earth and provide a way to search for new particles and new physics at high energies, without needing to build particle accelerators. Images of cosmic ray (and gamma-ray) extensive air showers are still widely used today in experimental particle physics.