Chadwick, James

English physicist James Chadwick was born on October 20, 1891 in Bollington near Manchester. After graduating from Manchester University he decided to defend his master's thesis under the supervision of Ernest Rutherford, who was then fascinated by his famous experiments on the passage of alpha radiation through metal foil (after which it became clear that this radiation was a stream of charged helium atoms). Rutherford suggested that the mass of an atom was concentrated in a positively charged nucleus surrounded by negatively charged electrons. There was probably no better place to start a career as a future atomic physicist at that time but Chadwick received a scholarship in 1913 and went to Germany to do an internship with Hans Geiger, a student of Rutherford. At the very beginning of the First World War Chadwick was arrested as a foreign agent and sent to a camp in Ruhleben for five years. It was practically impossible to do science in such conditions but the English physicist managed to organize a series of experiments on fluorescence with several other comrades in misfortune.

In 1919 Chadwick returned to Manchester. A new science, atomic physics, was already under development here. Rutherford discovered that bombarding a substance with alpha particles could cause its atoms to disintegrate into atoms of lighter elements. Rutherford was soon offered the position of head of the Cavendish Laboratory at Cambridge University, and he invited Chadwick to continue experiments with alpha particles together.

James Chadwick showed on various substances that target atoms really absorb alpha particles with the emission of a neutral particle and that its mass is almost equal to the mass of a proton. Thus, the legitimate birth of the neutron took place, and at the same time the proton-neutron model of the atomic nucleus was confirmed (independently of Chadwick and Rutherford, the same model of the nucleus was proposed by the Soviet physicist Dmitry Ivanenko). In 1935, Chadwick received the Nobel Prize for his discovery of the neutron.

In 1935, Chadwick moved to the University of Liverpool and supervised the construction of a cyclotron there. With the outbreak of World War II, the British government recruited him for the atomic project, and then he coordinated the work of British scientists in the American Manhattan Project, which resulted in the first atomic bomb. Chadwick spent the rest of his life in Cambridge.

The outstanding English physicist passed away on July 24, 1974.