‎"BOTHE, W. (+) H. BECKER.‎
‎Künstliche Erregung von Kern-y-Strahlen. - [ANTICIPATING THE DISCOVERY OF THE NEUTRON]‎

‎Berlin, Springer, 1930. 8vo. In contemporary halv cloth with gilt lettering to spine. In ""Zeitschrift für Physik"", Bd. 66, 1930. Entire volume offered. Stamp to front free end-paper, otherwise fine and clean. Pp. 289-310. [Entire volume: VIII, 863 pp.].‎

Reference : 49390

‎First appearance of Bothe and Becker's seminal paper in which they found that if the very energetic alpha particles emitted from polonium fell on certain light elements, an unusually penetrating radiation was produced. Two years later this led directly to Chadwick's discovery of the neutron. ""In 1930 Bothe and Becker detected a highly penetrative radiation from beryllium bombarded by alpha particles, and they assumed that it was gamma radiation. Bothe estimated the photon energy from the degree of absorption of the secondary electrons. When physicists studied this ""beryllium radiation,"" estimating its energy constituted a problem, for it varied greatly according to the substance used as absorber. Chadwick later suggested that the radiation was particulate and consisted of a new particle, the neutron.""‎