Wolfgang Gentner (23 July 1906 in Frankfurt am Main – 4 September 1980 in Heidelberg) was a German experimental nuclear physicist.
Gentner received his doctorate in 1930 from the University of Frankfurt. From 1932 to 1935 he had a fellowship which allowed him to do postdoctoral research and study at Curie's Radium Institute at the University of Paris. From 1936 to 1945, he was a staff scientist at the Institute of Physics at the Kaiser Wilhelm Institute for Medical Research, in Heidelberg. One of his areas of specialization was nuclear photoeffects. He was granted his Habilitation from the University of Frankfurt in 1937. At the end of 1938 and early 1939, he visited the Radiation Laboratory at the University of California, Berkeley; upon his return to Germany, he participated in the construction of a cyclotron at Heidelberg. During World War II, he participated in the German nuclear energy project, also called the Uranium Club. After World War II, Gentner became a professor at the University of Freiberg.
In 1956, Gentner was appointed director of the Synchrocyclotron Department at CERN. In 1958, he became director of the new Max Planck Institute for Nuclear Physics at Heidelberg. From 1967 to 1970, he was chairman of the Physicochemical-technical Section of the Max Planck Society. From 1969 to 1971, he was president of the Science Policy Committee and president of the council at CERN. From 1972, he was vice-president of the Max Planck Society. From 1975, he was a member of the board of governors at the Weizmann Institute of Science, Israel.
Gentner helped found a number of European scientific organizations during the 1960s. The prestigious Wolfgang Gentner Fellowship for PhD students at CERN is named after Gentner.
From 1925 to 1930, Gentner studied at the Friedrich-Alexander-Universität Erlangen-Nürnberg and the Johann Wolfgang Goethe-Universität Frankfurt am Main. While in his first semester at Erlangen, his father died, so he returned to Frankfurt to help care for his mother and continued his education at Frankfurt. He received his doctorate in 1930 under Friedrich Dessauer, who was director of the Institut für die physikalischen Grundlagen der Medizin (Institute for the Physical Fundamentals of Medicine), at the University of Frankfurt. His thesis was on the range of electrons in matter and their biological effects. In 1932, he was an auxiliary aid (Hilfsassistent) to Dessauer. From 1933 to 1935, he was a fellow of the Oswalt-Stiftung (Oswalt Foundation) of the University of Frankfurt and a fellow of the Carnegie Foundation, whose assistance he used to study at the Radium Institute of the University of Paris, which at that time was under the leadership of Marie Curie.
From 1936 to 1945, Gentner was a staff assistant at Walther Bothe's Institut für Physik at the Kaiser-Wilhelm Institut für medizinische Forschung (KWImF, Kaiser Wilhelm Institute for Medical Research; today, the Max-Planck Institut für medizinische Forschung), in Heidelberg. One of his areas of specialization was in nuclear photoeffects (Kernphotoeffekt).
In 1932, Walther Bothe had succeeded Philipp Lenard as director of the Physikalische und Radiologische Institut (Physics and Radiological Institute) at the University of Heidelberg. When Adolf Hitler became Chancellor of Germany on 30 January 1933, the concept of Deutsche Physik took on more favor as well as fervor; deutsche Physik, was anti-Semitic and anti-theoretical physics, especially modern physics, including quantum mechanics and both atomic and nuclear physics. As applied in the university environment, political factors took priority over the historically applied concept of scholarly ability, even though its two most prominent supporters were the Nobel Laureates in Physics Philipp Lenard and Johannes Stark. Supporters of deutsche Physik launched vicious attacks against leading theoretical physicists. While Lenard was retired from the University of Heidelberg, he still had significant influence there. In 1934, Lenard had managed to get Bothe relieved of his directorship of the Institute of Physics at the University of Heidelberg, whereupon Bothe was able to become the director of the Institut für Physik of the KWImF, replacing Karl W. Hauser, who had recently died. Ludolf von Krehl, director of the KWImF, and Max Planck, President of the Kaiser-Wilhelm Gesellschaft (KWG, Kaiser Wilhelm Society, today, the Max-Planck Gesellschaft), had offered the directorship to Bothe to ward off the possibility of his emigration. When it came time for Gentner to submit his Habilitationsschrift, Die Absorption, Streuung und Sekundärstrahlung harter Gamma-Strahlen (The absorption, scattering and secondary hard gamma rays), the relations between the KWImF and the University of Heidelberg were so strained that Habilitation was not possible there. So, Gentner completed the requirements at the University of Frankfurt, in 1937, and became a Privatdozent (lecturer) there. This necessitated making trips by train between the facilities, which soon became a burden.
By the end of 1937, the rapid successes Bothe and Gentner had with the building and research uses of a Van de Graaff generator had led them to consider building a cyclotron. By November, a report had already been sent to the president of the Kaiser-Wilhelm Gesellschaft (KWG, Kaiser Wilhelm Society; today, the Max Planck Society), and Bothe began securing funds from the Helmholtz-Gesellschaft (Helmholtz Society; today, the Helmholtz Association of German Research Centres), the Badischen Kultusministerium (Baden Ministry of Culture), I.G. Farben, the KWG, and various other research oriented agencies. Initial promises led to ordering a magnet from Siemens in September 1938, however, further financing then became problematic. In these times, Gentner continued his research on the nuclear photoeffect, with the aid of the Van de Graaff generator, which had been upgraded to produce energies just under 1 MeV. When his line of research was completed with the 7Li (p, gamma) and the 11B (p, gamma) reactions, and on the nuclear isomer 80Br, Gentner devoted his full effort to the building of the planned cyclotron.
In order to facilitate the construction of the cyclotron, at the end of 1938 and into 1939, with the help of a fellowship from the Helmholtz-Gesellschaft, Gentner was sent to Radiation Laboratory of the University of California (today, the Lawrence Berkeley National Laboratory) in Berkeley, California. As a result of the visit, Gentner formed a cooperative relationship with Emilio G. Segrè and Donald Cooksey.
The German nuclear energy project, also known as the Uranverein, began in the spring of 1939 under the auspices of the Reichsforschungsrat (RFR, Reich Research Council) of the Reichserziehungsministerium (REM, Reich Ministry of Education). By 1 September, the Heereswaffenamt (HWA, Army Ordnance Office) squeezed out the RFR and took over the effort. Under the control of the HWA, the Uranverein had its first meeting on 16 September. The meeting was organized by Kurt Diebner, advisor to the HWA, and held in Berlin. The invitees included Walther Bothe, Siegfried Flügge, Hans Geiger, Otto Hahn, Paul Harteck, Gerhard Hoffmann, Josef Mattauch, and Georg Stetter. A second meeting was held soon thereafter and included Klaus Clusius, Robert Döpel, Werner Heisenberg, and Carl Friedrich von Weizsäcker. With Bothe being one of the principals, Gentner was soon drawn into work for the Uranverein, along with other colleagues, such as Arnold Flammersfeld and Peter Herbert Jensen. Their research was published in the Kernphysikalische Forschungsberichte (Research Reports in Nuclear Physics); see below the section Internal Reports.
After the armistice between France and Germany in the summer of 1940, Bothe and Gentner received orders to inspect the cyclotron Frédéric Joliot-Curie had built in Paris. While it had been built, it was not yet operational. In September 1940, Gentner received orders to form a group to put the cyclotron into operation. Hermann Dänzer from the University of Frankfurt participated in this effort.