Joliot-Curie, Jean Frédéric

Born Mar. 19, 1900, in Paris; died there Aug. 14, 1958. French physicist. Progressive public figure and one of the founders and leaders of the World Peace Movement. Member of the Paris Academy of Sciences (1943) and foreign member of the Academy of Sciences of the USSR (1949; corresponding member, 1947).

In 1923, Joliot-Curie graduated from the School of Physics and Applied Chemistry, where he studied under P. Langevin. Following a short period of service in the army, he began working in the laboratory of Marie Sklodowska-Curie. In 1926 he married Iréne Curie. In 1930 he defended his doctoral dissertation. He began teaching at the Sorbonne in 1935. In 1937 he was appointed to the chair of nuclear physics and chemistry at the College de France, which he occupied until his death. Here Joliot-Curie established a laboratory of nu-clear physics and chemistry and constructed the first cyclotron in France. Beginning in 1937 he was also head of the laboratory for atomic synthesis at the National Center for Scientific Research. From 1946 to 1950 he was director of the Atomic Energy Commission founded by him. From 1956 he was head of the laboratory at the Radium Institute and director of the Institute for Nuclear Physics in Orsay.

Beginning in 1928, Joliot-Curie worked in the field of nu-clear physics. In 1934 the Joliot-Curies discovered the phenomenon of artificial radioactivity, for which they were awarded a Nobel Prize in 1935. This discovery marked the beginning of a new stage in the development of nuclear physics. Together with his wife and colleagues, Joliot-Curie also investigated nuclear reactions influenced by alpha particles and deuterons as well as methods of using artificially prepared radioactive isotopes as tagged atoms. His investigation of the properties of radiation arising during the bombardment of beryllium with alpha particles played an important role in the development of neutron physics. Joliot-Curie showed (1934) that the mass of a neutron is somewhat larger than that of a proton. From this it could be concluded that a neutron may be beta radioactive. This supposition by Joliot-Curie was proved to be correct in 1951 when the beta decay of a neutron was discovered. One important series of re-searches by Joliot-Curie and his wife was devoted to the study of the annihilation and creation of pairs. He showed that the energy of a gamma quantum is converted to the energy of the pair.

After J. Chadwick’s discovery of the neutron, Joliot-Curie was one of the first to note the importance of this discovery for the practical utilization of atomic energy. He also published a series of works that proved to be among the first studies of the fission of heavy nuclei and the formation of transuranium elements. Together with the French scientists H. Halban and L. Kowarski, Joliot-Curie was the first to determine (in early 1939) the average number of secondary neutrons escaping during the nuclear fission of a uranium atom. He also showed the possibility in principle of a nuclear chain reaction with the release of atomic energy, but this work was interrupted by the war. After World War II (1939–45) Joliot-Curie directed the construction of the first atomic reactor in France, which was put in operation on Dec. 15, 1948 (Fort Châtillon).

Joliot-Curie took an active part in public life. In 1934 he became a member of the Socialist Party. During the occupation of France by fascist German troops (1940–44) he was a participant in the Resistance Movement and head of the organization Front National. In 1942 he became a member of the French Communist Party. He took part in the antifascist Paris uprising of August 1944. From 1947 he was president of the society France-USSR. In 1946 he became president of the World Federation of Scientific Workers. The name of Joliot-Curie is associated with the birth of the World Peace Movement. He became chairman of the World Peace Council following its formation in November 1950. Joliot-Curie was awarded the International Lenin Prize for Strengthening Peace Among Peoples (1951). In 1956 he was elected member of the central committee of the French Communist Party.