Wolfgang Gentner (23 July 1906 inFrankfurt am Main – 4 September 1980 inHeidelberg)[1] was a German experimentalnuclear physicist.
Gentner received his doctorate in 1930 from the University of Frankfurt. From 1932 to 1935 he had a fellowship which allowed him to dopostdoctoral 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 hisHabilitation from the University of Frankfurt in 1937. At the end of 1938 and early 1939, he visited the Radiation Laboratory at theUniversity of California, Berkeley; upon his return to Germany, he participated in the construction of acyclotron at Heidelberg. DuringWorld War II, he participated in theGerman 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 atCERN.[2] In 1958, he became director of the newMax 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 theWeizmann Institute of Science, Israel.
Gentner helped found a number of European scientific organizations during the 1960s. The prestigious Wolfgang Gentner Fellowship for PhD students atCERN is named after Gentner.[3]
From 1925 to 1930, Gentner studied at theFriedrich-Alexander-Universität Erlangen-Nürnberg and theJohann 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 underFriedrich Dessauer, who was director of theInstitut 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 theOswalt-Stiftung (Oswalt Foundation) of the University of Frankfurt and a fellow of theCarnegie Foundation, whose assistance he used to study at the Radium Institute of theUniversity of Paris, which at that time was under the leadership ofMarie Curie.[4][5][6]
From 1936 to 1945, Gentner was a staff assistant at Walther Bothe'sInstitut für Physik at theKaiser-Wilhelm Institut für medizinische Forschung (KWImF, Kaiser Wilhelm Institute for Medical Research; today, theMax-Planck Institut für medizinische Forschung), in Heidelberg. One of his areas of specialization was in nuclear photoeffects (Kernphotoeffekt).[5][6][7][8]
In 1932, Walther Bothe had succeededPhilipp Lenard as director of thePhysikalische und Radiologische Institut (Physics and Radiological Institute) at the University of Heidelberg. WhenAdolf Hitler became Chancellor of Germany on 30 January 1933, the concept ofDeutsche Physik took on more favor as well as fervor;deutsche Physik, wasanti-Semitic and anti-theoretical physics, especially modern physics, includingquantum 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,[9] even though its two most prominent supporters were theNobel Laureates in Physics Philipp Lenard[10] andJohannes Stark.[11] Supporters ofdeutsche 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 theInstitut für Physik of the KWImF, replacing Karl W. Hauser, who had recently died.Ludolf von Krehl, director of the KWImF, andMax Planck, President of theKaiser-Wilhelm Gesellschaft (KWG, Kaiser Wilhelm Society, today, theMax-Planck Gesellschaft), had offered the directorship to Bothe to ward off the possibility of his emigration. When it came time for Gentner to submit hisHabilitationsschrift,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 thatHabilitation was not possible there. So, Gentner completed the requirements at the University of Frankfurt, in 1937, and became aPrivatdozent (lecturer) there. This necessitated making trips by train between the facilities, which soon became a burden.[4][6][12][13]
By the end of 1937, the rapid successes Bothe and Gentner had with the building and research uses of aVan de Graaff generator had led them to consider building a cyclotron. By November, a report had already been sent to the president of theKaiser-Wilhelm Gesellschaft (KWG, Kaiser Wilhelm Society; today, the Max Planck Society), and Bothe began securing funds from theHelmholtz-Gesellschaft (Helmholtz Society; today, theHelmholtz Association of German Research Centres), theBadischen Kultusministerium (Baden Ministry of Culture),I.G. Farben, the KWG, and various other research oriented agencies. Initial promises led to ordering a magnet fromSiemens 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 the7Li (p, gamma) and the11B (p, gamma) reactions, and on the nuclear isomer80Br, Gentner devoted his full effort to the building of the planned cyclotron.[4]
In order to facilitate the construction of the cyclotron, at the end of 1938 and into 1939, with the help of a fellowship from theHelmholtz-Gesellschaft, Gentner was sent to Radiation Laboratory of the University of California (today, theLawrence Berkeley National Laboratory) in Berkeley, California. As a result of the visit, Gentner formed a cooperative relationship withEmilio G. Segrè andDonald Cooksey.[4]
TheGerman nuclear energy project, also known as theUranverein, began in the spring of 1939 under the auspices of theReichsforschungsrat (RFR, Reich Research Council) of theReichserziehungsministerium (REM, Reich Ministry of Education). By 1 September, theHeereswaffenamt (HWA, Army Ordnance Office) squeezed out the RFR and took over the effort. Under the control of the HWA, theUranverein had its first meeting on 16 September. The meeting was organized byKurt Diebner, advisor to the HWA, and held in Berlin. The invitees includedWalther Bothe,Siegfried Flügge,Hans Geiger,Otto Hahn,Paul Harteck,Gerhard Hoffmann,Josef Mattauch, andGeorg Stetter. A second meeting was held soon thereafter and includedKlaus Clusius,Robert Döpel,Werner Heisenberg, andCarl Friedrich von Weizsäcker. With Bothe being one of the principals, Gentner was soon drawn into work for theUranverein, along with other colleagues, such asArnold Flammersfeld andPeter Herbert Jensen. Their research was published in theKernphysikalische Forschungsberichte (Research Reports in Nuclear Physics); see below the sectionInternal Reports.[14][15][16]
After the armistice between France and Germany in the summer of 1940, Bothe and Gentner received orders to inspect the cyclotronFrédéric 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.
According to author Robert Jungk in his landmark work,Brighter Than A Thousand Suns, Gentner only agreed to take over Joliot-Curie's laboratory after he had received Joliot-Curie's express consent - and the two men crafted a secret agreement that the laboratory would not complete work that supported the German war effort.[17]
While in Paris, Gentner intervened personally to free both Frédéric Joliot-Curie andPaul Langevin after they were arrested and detained. At the end of the winter of 1941/1942, the cyclotron was operational with a 7-MeV beam ofdeuterons.Uranium andthorium were irradiated with the beam, and the byproducts were sent to Otto Hahn at theKaiser-Wilhelm Institut für Chemie (KWIC, Kaiser Wilhelm Institute for Chemistry, today, theMax Planck Institute for Chemistry), in Berlin. In mid-1942, according to Jungk, Gentner was relieved of his duties because of the "weakness" he had shown. His successor in Paris was Wolfgang Riezler fromBonn.[4][18][19]
A next mission of the HWA was the completion of the Heidelberg cyclotron. It was during 1941 that Bothe had acquired all the necessary funding to complete construction. The magnet was delivered in March 1943, and the first beam of deuteron was emitted in December. The inauguration ceremony for the cyclotron was held on 2 June 1944.[4]
In 1941, Gentner was authorized as aDozent (lecturer) with aLehrauftrag (teaching assignment) at the University of Heidelberg.[4][5]
In 1946, Gentner became anordentlicher Professor (ordinarius professor) at theAlbert-Ludwigs-Universität Freiburg, where he worked on nuclear andcosmic-ray physics. From 1947 to 1949, he was alsoProrektor (vice-rector) of the university.[4][5]
During 1956 and 1957, Gentner was a member of theArbeitskreis Kernphysik (Nuclear Physics Working Group) of theFachkommission II "Forschung und Nachwuchs" (Commission II "Research and Growth") of theDeutschen Atomkommission (DAtK, German Atomic Energy Commission). Other members of the Nuclear Physics Working Group in both 1956 and 1957 were:Werner Heisenberg (chairman),Hans Kopfermann (vice-chairman),Fritz Bopp,Walther Bothe,Otto Haxel,Willibald Jentschke,Heinz Maier-Leibnitz,Josef Mattauch,Wolfgang Riezler [de],Wilhelm Walcher, andCarl Friedrich von Weizsäcker.Wolfgang Paul was also a member of the group during 1957.[20]
In 1956, soon after the founding ofCERN, inGeneva, Gentner was appointedDirektor der Abteilung Synchrozyklotron (Director of theSynchrocyclotron Department) andDirektor der Forschung (Director of Research), positions which he held until October 1958. His department was responsible for the construction of their 600-MeV synchrocyclotron. Parallel to this, he had also been asked by theStuttgarter Landesregierung (Stuttgart State Government) to be the first head of theKernforschungszentrum Karlsruhe (KfK, Karlsruhe Nuclear Research Centre, today theForschungszentrum Karlsruhe), whose construction had just been decided. Gentner declined so as to stay with more fundamental research, rather than applied. The synchrocyclotron at CERN delivered its first beam on 1 August 1957. From 1971 to 1974, he was chairman of the CERN board.[4][5][21]
At the end of 1957, Gentner was in negotiations with Otto Hahn, President of theMax-Planck Gesellschaft (MPG, Max Planck Society, successor of theKaiser-Wilhelm Gesellschaft), and with the Senate of the MPG to establish a new institute under their auspices. Essentially, Walther Bothe'sInstitut für Physik at theMax-Planck Institut für medizinische Forschung, in Heidelberg, was to be spun off and become a full-fledged institute of the MPG. The decision to proceed was made in May 1958. Gentner was named the director of theMax-Planck Institut für Kernphysik (MPIK, Max Planck Institute for Nuclear Physics) on 1 October, and he also received the position as anordentlicher Professor (ordinarius professor) at the University of Heidelberg. Bothe had not lived to see the final establishment of the MPIK, as he had died in February of that year.[4][22]
In 1959, in collaboration with his Heidelberg colleagues Otto Haxel andJ. Hans D. Jensen, Gentner closed negotiations with theHeidelberger Gemeinderates (Heidelberg Local Council) to build a 6-Mev tandem-accelerator and a special building for the study of cosmic physics.[4]
From 1967 to 1970, Gentner wasVorsitzender (chairman) of thephysikalisch-chemisch-technischen Sektion (Physicochemical-technical Section) of the Max-Planck Gesellschaft. During this period, theMax-Planck-Institut für Astronomie (Max Planck Institute for Astronomy) was founded in Heidelberg. At the end of his term as section chairman, Gentner had two medical operations, one forcataracts, which were attributed to neutron radiation exposure from his early years of experimental nuclear research.[4]
At CERN, from 1969 to 1971, Gentner wasVorsitzender des Wissenschaftsausschusses (President of the Science Policy Committee) and from 1972 to 1974Präsident des Rates (President of the Council).[4]
From 1972, Gentner was Vice-president of the Max-Planck Gesellschaft. This was a particularly critical period for the MPG for purposes of consolidation, after 10 years of expansion.[5]
From 1975, Gentner was a member of the board of governors at theWeizmann Institute of Science, in Israel.[4][5]
In the second half of the 1960s, Gentner helped scientific colleagues with establishing scientific institutions. With his knowledge of French science, Gentner helped Heinz Maier-Liebnitz with the establishment of theInstitut Laue-Langevin inGrenoble. Gentner also helped Christoph Schmelzer establish theGesellschaft für Schwerionenforschungs (GSI, Society for Heavy Ion Research), inDarmstadt. In 1968, inFlorence, Gentner and Gilberto Bernardini founded of theEuropean Physical Society.[4][23]
During his career, Gentner demonstrated his interest inKosmochemie und Archäometrie (cosmochemistry andarchaeometry), which are fields at the intersection of cultural and natural sciences.[24]
Gentner was a member of many scientific academies and was awarded a number of honors:[4]
Gentner married Alice Pfaehler. They had a son Ralph and a daughter Doris.[4]
The following reports were published inKernphysikalische Forschungsberichte (Research Reports in Nuclear Physics), an internal publication of the GermanUranverein. The reports were classified Top Secret, they had very limited distribution, and the authors were not allowed to keep copies. The reports were confiscated under the AlliedOperation Alsos and sent to theUnited States Atomic Energy Commission for evaluation. In 1971, the reports were declassified and returned to Germany. The reports are available at theKarlsruhe Nuclear Research Center and theAmerican Institute of Physics.[30][31]
