Cecil Frank Powell

Cecil Frank Powell was born in Tonbridge, Kent, England, on December 5, 1903. His father, Frank Powell, came from a family of gunsmiths. At the age of eleven Powell won a scholarship to the Judd School in Tonbridge.⁠[1][2]

Powell entered Sidney Sussex College, Cambridge, in 1921 and gained First Class Honours in the Natural Sciences Tripos in 1924 and 1925.⁠[3][1]

From 1925 Powell carried out research at the Cavendish Laboratory under C. T. R. Wilson and Ernest Rutherford, receiving his PhD in 1927.⁠[1][3]

In 1927 Powell went to the University of Bristol as research assistant to A. M. Tyndall. He became Lecturer in Physics in 1931 and was later promoted to Reader.⁠[4][3][1]

His early research on the supersaturation of steam had a bearing on the design of steam turbines; he also studied the mobility of ions in gases.⁠[1]

In 1932 Powell married Isobel Therese Artner; they had two daughters.⁠[1][3]

In 1936 Powell served as seismologist on an expedition to study volcanic activity in the West Indies.⁠[1][5]

From 1938 Powell studied cosmic radiation using photographic plates exposed at high altitudes, and between 1939 and 1945 he developed techniques for recording the paths of cosmic-ray particles in sensitive photographic emulsions.⁠[5][6]

In 1947 data from Powell’s photographic emulsions revealed the pion and its decay. Track analysis published that year in Nature by Powell, César Lattes and Giuseppe Occhialini showed that the pion decays spontaneously into the muon. The pion matched the particle proposed theoretically by Hideki Yukawa in 1935.⁠[7][6][5]

A large group of young women, known as “Cecil’s Beauty Chorus,” scanned the photographic plates for events, work that was essential to the discoveries.⁠[7]

In 1947 Powell received the Physical Society’s Vernon Boys Prize and became an Honorary Fellow of the Society.⁠[1]

In 1948 Powell became Melville Wills Professor of Physics at the University of Bristol.⁠[4][1]

In 1949 Powell was elected a Fellow of the Royal Society (FRS) and awarded its Hughes Medal. In the same year he identified the decay modes of the K-meson.⁠[1][6]

Powell was the sole recipient of the 1950 Nobel Prize in Physics, awarded “for his development of the photographic method of studying nuclear processes and his discoveries regarding mesons made with this method.” At the time of the award he was affiliated with the University of Bristol.⁠[8][2]

On December 11, 1950, Powell delivered his Nobel Lecture, “The Cosmic Radiation.”⁠[9]

In 1952 Powell directed European high-altitude balloon flights in Sardinia, followed by flights in the Po Valley in Italy in 1954, 1955 and 1957.⁠[1][3]

In 1955 Powell signed the Russell–Einstein Manifesto, issued by Bertrand Russell and Albert Einstein, which called on scientists of all political persuasions to meet and discuss the threat posed by thermonuclear weapons. He then helped to prepare the first Pugwash Conference.⁠[10][5]

The first Pugwash Conference on Science and World Affairs was held in 1957 at Pugwash, Nova Scotia, Canada, with 22 scientists attending. Powell took part and presented the paper “The Significance of Our Times and the Social Responsibility of Scientists” in Committee Three.⁠[10][5]

In 1961 Powell received the Royal Society’s Royal Medal and served on CERN’s Scientific Policy Committee, which he chaired.⁠[1][3]

In 1964 Powell became Director of the H. H. Wills Physics Laboratory at the University of Bristol.⁠[6][3]

With Don Perkins and Peter Fowler, Powell extended the emulsion method to high-altitude balloon exposures, and in 1966 they produced the first examples of ultra-heavy cosmic-ray particles.⁠[7]

Powell died at Casargo, Italy, on August 9, 1969, aged 65.⁠[6][2]

Powell pioneered the use of photographic emulsions to detect energetic particles and developed the photographic emulsion method in nuclear physics. The University of Bristol’s School of Physics traces the origins of its high-energy particle physics and astrophysics research to him.⁠[7][1]

Powell co-authored Nuclear Physics in Photographs (1947) and The Study of Elementary Particles by the Photographic Method (1959).⁠[1]

Powell received honorary Doctor of Science degrees from universities including Dublin, Bordeaux and Warsaw, and was a Foreign Member of the USSR Academy of Sciences. He also gave the Royal Society’s Bakerian Lecture and Tercentenary Lecture, and received the Lomonosov Gold Medal of the USSR Academy of Sciences and the Guthrie Medal of the Institute of Physics.⁠[1][3]

Powell was President of the Association of Scientific Workers and President of the World Federation of Scientific Workers, and chaired the Cosmic Ray Commission of the International Union of Pure and Applied Physics (IUPAP); he was also a member of the Science Research Council and chairman of its Nuclear Physics Board.⁠[3][7]

He chaired the Pugwash Continuing Committee, often standing in for Bertrand Russell, and attended its meetings until 1968. Joseph Rotblat wrote that Powell gave the Pugwash movement “coherence, endurance and vitality.”⁠[5]

The University of Bristol includes Powell in its list of Nobel laureates. At the university he also held the Henry Overton Wills Professorship of Physics and served as Pro-Vice-Chancellor, and his papers and correspondence are held in the University of Bristol Library.⁠[4][3]