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Early years Bothe was born in Oranienburg, Germany (near Berlin) and studied physics from 1908 until 1912 at the University of Berlin under Max Planck, earning his doctorate by 1914. During World War I he was taken prisoner by the Russians and spent a year in captivity in Siberia. After the war, he collaborated with Hans Geiger at Physikalisch-Technische Reichsanstalt in Berlin, where he made his most important discoveries. He discovered that if a single particle is detected by two or more Geiger counters, the detection will be practically coincident in time. Using this observation, he constructed the coincidence circuit allowing several counters in coincidence to determine the angular momentum of a particle. Bothe's coincidence circuit was one of the first AND logic gates (1924). Bothe studied the Compton effect using such a set up, thus establishing the modern analysis of scatter processes. Middle years During the 1920s, Bothe used the coincidence method to discover penetrating radiation coming from the upper atmosphere; this radiation is now known as cosmic rays. His data indicated that the radiation was not composed exclusively of gamma rays, but was also composed of high energy particles (now known to be mostly mesons). Bothe began applying the coincidence method to the transmutation of light elements by the bombardment with alpha particles in 1927. In the 1930s, he found that the radiation emitted by beryllium when it is bombarded with alpha particles was a new form of penetrating high energy radiation, which was later shown by James Chadwick to be neutrons. Bothe taught at the University of Berlin from 1920 to 1931, at the University of Giessen from 1931 to 1934 and in 1932 was appointed Director of the Institute of Physics at the University of Heidelberg, succeeding Philipp Lenard. He also began working at the Kaiser Wilhelm Institute (now the Max Planck Institute) at this time. In 1934, Bothe became Director of the Institute of Physics at the Max Planck Institute for Medical Research. In 1938, Wolfgang Gentner and Bothe published a paper on the energy dependence of the nuclear photo-effect, which was the first decisive evidence that the absorption spectra of nuclei are accumulative and continuous. Later years and death In 1941, Bothe and Peter Jensen reported the results of testing on neutron absorption in graphite. However, their erronous conclusions contributed to stifling the German nuclear program in World War II. In 1943, Bothe completed Germany's first cyclotron, and was awarded the Max Planck medal in 1953. Bothe continued to work at the Institute of Physics in the Max Planck Institute until his death in Heidelberg in 1957. Personal life Bothe considered himself a German patriot, and did not believe that his German weapons research during the Second World War required an excuse. Bothe married Barbara Below of Moscow and had two children. He was interested in music (playing the piano) and painting (oil painting and water color). Bothe was sensitive to criticism and kept problems privately. Publications See also Robert S. Mulliken, Neutron, Nobel Prize in Physics, 1954 in science, Compton effect Notes | ||||||||||
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