Walther Wilhelm Georg Bothe (January 8, 1891 - February 8, 1957) was a German physicist, mathematician, chemist, and Nobel Prize winner. Bothe won a Nobel Prize in Physics for 1954 (along with Max Born) for his invention of the coincidence circuit.
He was born in Oranienburg, Germany (near Berlin) and studied physics from 1908 until 1912 at the University of Berlin under Max Planck. Bothe obtaining his doctorate by 1914. During World War I he was taken prisoner by the Russians and spent 5 years 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 gate (1924). Bothe studied the Compton effect using such a set up and establishing the modern analysis of scatter processes.
During the 1920s Bothe used the coincidence method to discovery penetrating radiation coming from the upper atmosphere now known as cosmic rays. His data indicated that the tradition 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 a new form of penetrating high energy radiation, which was later shown by James Chadwick to be neutrons.
The 1932 appointment made Bothe at the University of Heidelberg the Director of the Institute of Physics. He successed Philipp Lenard. Bothe started working at the Kaiser Wilhelm Institute (now the Max Planck Institute). 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 the energy dependence of the nuclear photo-effect, which was the first decisive evidence that absorption spectra of nuclei are accumulative and continuous.
Later years and death
In 1941, Bothe and Peter Jensen report results on neutron absorption in graphite. Their erronous conclusions contributed to stifling the German nuclear program in World War II. In 1943, Bothe completed Germany's first cyclotron. Bothe continued to work at the Institute of Physics in the Max Planck Institute until his death in Heidelberg. Bothe died in 1957.
Bothe considered himseld a German patriot. Bothe married Barbara Below of Moscow and had two children. Bothe was interested in music (playing the piano) and painting (oil painting and water color). Bothe was a loner. Bothe was sensitive to criticism and kept problems privately. He did not believe that his German weapons research during the Second World War deserved an excuse.
Bothe, W. and Hans Geiger, "Experimentaler Teil". 1921.
Bothe, W., "Bemerkung yur vorstehenden Arbeit". 1921.
Bothe, W., "Remarks on the Leipziger DŌ attempt". 1941.
Bothe, W., "The distribution of velocity of the neutrons in a braking means". 1942.
Bothe, W., "The vermehrung of fast neutrons in uranium and some other work from the KWI Heidelberg".
Bothe, W., "Over radiation protection walls".
Bothe, W. and W. Fuenfer, "Layer attempts with variation of the u and DŌ thicknesses".