Hans Halban (26.01.1908-28.02.1964)- experimental physicist. Born in Leipzig. Graduated from the University of Zurich. In 1935 he worked at the Radium Institute (Paris) with I. Joliot-Curie, in 1936 at the Institute of Theoretical Physics in Copenhagen with N. Bohr, and in 1937—40 at the Collège de France with F. Joliot-Curie. During the war he worked at the Cavendish and Montreal laboratories, and after the war at the University of Oxford. From 1955 he was a professor at the University of Paris, and from 1959 at the École Normale.
His research was in nuclear physics and nuclear engineering. Independently of others he discovered (1936) the diffraction of neutrons. In 1939, together with F. Joliot-Curie and L. Kowarski, he detected the emission of secondary neutrons (more than one) in the fission of uranium nuclei and postulated the nuclear chain reaction. With L. Kowarski he obtained (1940) proof that a nuclear chain reaction is possible in a system of uranium and heavy water, and proposed using a movable cadmium rod to regulate the chain process. He studied the properties of slow neutrons, the photodisintegration of the deuteron, and nuclear levels.