The most outstanding contributions of the German physicist Walther Bothe (1891-1957) were the invention of the coincidence method for the study of individual atomic and nuclear processes and the discovery of a nuclear radiation later identified as neutron emission.

Walther Bothe was born on Jan. 8, 1891, in Oranienburg near Berlin. He went to the University of Berlin, where, in addition to physics and mathematics, he did considerable work in chemistry. He was a pupil of Max Planck and wrote under Planck's mentorship his doctoral dissertation on the molecular theory of refraction, reflection, dispersion, and extinction.

Understanding the Compton Effect

After serving as an officer in World War I, Bothe returned to Berlin, where he started research with the rank of Regierungsrat (government counselor) at the Physikalisch-Technische Reichsanstalt, the German equivalent of the National Bureau of Standards in Washington, D.C. His immediate superior was Hans Geiger, director of the...