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physicist who investigated the charged subatomic particles in cosmic radiation
by using photographic emulsions carried in weather balloons. This led to
his discovery of the pion ( meson) 1947, a particle whose existence had
been predicted by Japanese physicist Hideki Yukawa 1935. Powell was awarded
a Nobel prize 1950. Powell was born in Tonbridge, Kent, and studied at Cambridge, where he carried out research at the Cavendish Laboratory under Ernest Rutherford and C T R Wilson, taking photographs of particle tracks in a cloud chamber. From 1928 Powell worked at the Wills Physics Laboratory at Bristol University, becoming professor 1948. In 1938, instead of photographing the cloud-chamber tracks, Powell made the ionizing particles trace paths in the emulsions of a stack of photographic plates. The technique received a boost with the development of more sensitive emulsions during World War II and Powell used it in his discovery of the pion. He collaborated with Italian physicist Giuseppe Occhialini (1907- ), and together they published Nuclear Physics in Photographs 1947, which became a standard text on the subject. |