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Cecil Frank Powell (December 5, 1903 - August 9, 1969) was a British physicist, awarded the Nobel Prize for Physics in 1950 for his development of the photographic method of studying nuclear processes and for the resulting discovery of the pion (pi-meson), a heavy subatomic particle. His collaborators in the study, published in 1947, were Giuseppe Occhialini, H. Muirhead and young Brazilian physicist César Lattes. The pion proved to be the hypothetical particle proposed in 1935 by Yukawa Hideki of Japan in his theory of nuclear physics. Powell was also awarded the Lomonosov Gold Medal in 1967, and was a signatory to the Russell-Einstein Manifesto in 1955.

References

Lattes, C. M. G., Muirhead, H., Occhialini, G. P. S. & Powell, C. F. Processes involving charged mesons. Nature, 159, 694 - 697, (1947).