James Chadwick
In 1930, he became an "ordentlicher Professor" and director of the physics department at the "Justus Liebig-Universität Gießen". That year, working with Herbert Becker, Bothe bombarded beryllium, boron, and lithium with alpha particles from polonium and observed a new form of penetrating radiation. In 1932, James Chadwick identified this radiation as the neutron.