Riehl was born in Saint Petersburg, Russia in 1901. His mother Elena Riehl (née Kagan) was Russian-Jewish^[1] and his father Wilhelm Gottfried Riehl was a professional German engineer employed by Siemens and Halske. With this background, Riehl spoke fluent German and Russian. From 1920 to 1927, he studied physics and physical chemistry at the Humboldt University of Berlin. He received his doctorate in nuclear physics from the University of Berlin in 1927, under the guidance of the nuclear physicist Lise Meitner and the nuclear chemist Otto Hahn; his thesis topic was on Geiger-Müller counters for beta ray spectroscopy.^[2][3]

Early years edit

Riehl initially took a position in German industry with Auergesellschaft, where he became an authority on luminescence. While he completed his Habilitation, he continued his industrial career at Auergesellschaft, as opposed to working in academia. From 1927, he was a staff scientist in the radiology department. From 1937, he was head of the optical engineering department. From 1939 to 1945, he was the director of the scientific headquarters.^[2][4]

Auergesellschaft had a substantial amount of "waste" uranium from which it had extracted radium. After reading a paper in 1939 by Siegfried Flügge, on the technical use of nuclear energy from uranium,^[5][6] Riehl recognized a business opportunity for the company, and, in July of that year, went to the Heereswaffenamt (HWA, Army Ordnance Office) to discuss the production of uranium. The HWA was interested and Riehl committed corporate resources to the task. The HWA eventually provided an order for the production of uranium oxide, which took place in the Auergesellschaft plant in Oranienburg, north of Berlin.^[7][8]

In the Soviet Union edit

Near the close of World War II, as American, British, and Russian military forces were closing in on Berlin, Riehl and some of his staff moved to a village west of Berlin, to try and assure occupation by British or American forces. However, in mid-May 1945, with the assistance of Riehl's colleague Karl Günter Zimmer, the Russian nuclear physicists Georgy Flerov and Lev Artsimovich showed up one day in NKVD colonel's uniforms.^[9][10] The use of Russian nuclear physicists in the wake of Soviet troop advances to identify and "requisition" equipment, materiel, intellectual property, and personnel useful to the Russian atomic bomb project is similar to the American Operation Alsos. The military head of Alsos was Lt. Col. Boris Pash, former head of security on the American atomic bomb effort, the Manhattan Project, and its chief scientist was the eminent physicist Samuel Goudsmit. In early 1945, the Soviets initiated an effort similar to Alsos (Russian Alsos). Forty out of less than 100 Russian scientists from the Soviet atomic bomb project's Laboratory 2^[11] went to Germany, Austria, and Czechoslovakia in support of acquisitions for the project.^[12]

The two colonels requested that Riehl join them in Berlin for a few days, where he also met with nuclear physicist Yulii Borisovich Khariton, also in the uniform of an NKVD colonel. This sojourn in Berlin turned into 10 years in the Soviet Union! Riehl and his staff, including their families, were flown to Moscow on 9 July 1945.^[10][13][14] Eventually, Riehl's entire laboratory was dismantled and transported to the Soviet Union.^[15]

Other prominent German scientists from Berlin who were taken to the Soviet Union at that time, and who would cross paths with Riehl, were Manfred von Ardenne, director of his private laboratory Forschungslaboratoriums für Elektronenphysik, Gustav Hertz, Nobel Laureate and director of Research Laboratory II at Siemens, Peter Adolf Thiessen, ordinarius professor at the Humboldt University of Berlin and director of the Kaiser-Wilhelm Institut für physikalische Chemi und Elektrochemie (KWIPC) in Berlin-Dahlem, and Max Volmer, ordinarius professor and director of the Physical Chemistry Institute at the Berlin Technische Hochschule. Soon after being taken to the Soviet Union, Riehl, von Ardenne, Hertz, and Volmer were summoned for a meeting with Lavrentij Beria, head of the NKVD and the Soviet atomic bomb project.^[16][17]

When a Soviet search team arrived at the Auergesellschaft facility in Oranienburg, they found nearly 100 tons of fairly pure uranium oxide. The Soviet Union took this uranium as reparations, which amounted to between 25% and 40% of the uranium taken from Germany and Czechoslovakia at the end of the war. Khariton said the uranium found there saved the Soviet Union a year on its atomic bomb project.^[18][19][20]

From 1945 to 1950, Riehl was in charge of uranium production at Plant No. 12 in Ehlektrostal' (Электросталь^[21]).^[22] German scientists, who were mostly atomic scientists, sent by the Soviets, at the close of World War II, to work in the Riehl group at Plant No. 12 included A. Baroni (PoW), Hans-Joachim Born, Alexander Catsch (Katsch), Werner Kirst, H. E. Ortmann, Herbert Schmitz (PoW), Walter Sommerfeldt, Herbert Thieme, Günter Wirths, and Karl Günter Zimmer as well as Heinrich Tobien, formerly "Chemiemeister" at Auergesellschaft; Walter Przybilla, brother of Riehl's wife, and mentioned in this context, also spent 10 years in SU, but was not a scientist under Riehl. While Born, Catsch, and Zimmer had collaborated with Riehl in Germany, they were actually not part of Auergesellschaft but with N. V. Timofeev-Resovskij's genetics department^[23] at the Kaiser-Wilhelm Gesellschaft's Institut für Hirnforschung (KWIH, Kaiser Wilhelm Institute for Brain Research) in Berlin-Buch. Riehl had a hard time incorporating these three into his tasking at Plant No. 12 on his uranium production tasking, as Born was a radiochemist, Catsch was a physician and radiation biologist, and Zimmer was a physicist and radiation biologist.^[24][25][26]

The Ehlektrostal' Plant No. 12, by the last quarter of 1946, was delivering about three metric tons of metallic uranium per week to Laboratory No. 2., which was later known as the Kurchatov Institute of Atomic Energy. By 1950, Plant No. 12 was producing about one metric ton per day, and it was not the only metallic uranium production plant in operation.^[27]

After the detonation of the Russian uranium bomb, uranium production was going smoothly and Riehl's oversight was no longer necessary at Plant No. 12. Riehl then went, in 1950, to head an institute in Sungul', where he stayed until 1952. Essentially the remaining personnel in his group were assigned elsewhere, with the exception of H. E. Ortmann, A. Baroni (PoW), and Herbert Schmitz (PoW), who went with Riehl. However, Riehl had already sent Born, Catsch, and Zimmer to the institute in December 1947. The German contingent at the institute in Sungul' never exceeded 26 – in 1946 there were 95 people at the facility, which grew to 451 by 1955, and the German contingent had already left a few years before that. Besides those already mentioned, other Germans at the institute were Rinatia von Ardenne (sister of Manfred von Ardenne, director of Institute A, in Sukhumi) Wilhelm Menke, Willi Lange (who married the widow of Karl-Heinrich Riewe, who had been at Heinz Pose's Laboratory V, in Obninsk), Joachim Pani, and K. K. Rintelen. The institute in Sungul' was responsible for the handling, treatment, and use of radioactive products generated in reactors, as well as radiation biology, dosimetry, and radiochemistry. The institute was known as Laboratory B, and it was overseen by the 9th Chief Directorate of the NKVD (MVD after 1946), the same organization which oversaw the Russian Alsos operation. The scientific staff of Laboratory B – a ShARAShKA – was both Soviet and German, the former being mostly political prisoners or exiles, although some of the service staff were criminals.^[28][29][30] (Laboratory V, in Obninsk, headed by Heinz Pose, was also a sharashka and working on the Soviet atomic bomb project. Other notable Germans at the facility were Werner Czulius, Hans Jürgen von Oertzen, Ernst Rexer, and Carl Friedrich Weiss.^[31])

Laboratory B was known under another cover name^[32] as Объект 0211 (Ob'ekt 0211, Object 0211), as well as Object B.^{[33][34][35][36]} (In 1955, Laboratory B was closed. Some of its personnel were transferred elsewhere, but most of them were assimilated into a new, second nuclear weapons institute, Scientific Research Institute-1011, NII-1011, today known as the Russian Federal Nuclear Center All-Russian Scientific Research Institute of Technical Physics, RFYaTs–VNIITF. NII-1011 had the designation предприятие п/я 0215, i.e., enterprise post office box 0215 and Объект 0215; the latter designation has also been used in reference to Laboratory B after its closure and assimilation into NII-1011.^{[30][37][38][39]})

One of the political prisoners in Laboratory B was Riehls' colleague from the KWIH, N. V. Timofeev-Resovskij, who, as a Soviet citizen, was arrested by the Soviet forces in Berlin at the conclusion of the war, and he was sentenced to 10 years in the Gulag. In 1947, Timofeev-Resovskij was rescued out of a harsh Gulag prison camp, nursed back to health, and sent to Sungul' to complete his sentence, but still make a contribution to the Soviet atomic bomb project. At Laboratory B, Timofeev-Resovskij headed the radiobiology department at Laboratory B, and another political prisoner, S. A. Voznesenskij, headed the radiochemistry department. At Laboratory B, Born, Catsch, and Zimmer were able to conduct work similar to that which they had done in Germany, and all three became section heads in Timofeev-Resovskij's department.^[28][29][30]

Until Riehl's return to Germany in June 1955, which Riehl had to request and negotiate, he was quarantined in Agudseri (Agudzery, in Russian Агудзера) starting in 1952. The home in which Riehl lived had been designed by Max Volmer and had been previously occupied by Gustav Hertz, when he was director of Laboratory G.^[40]

For his contributions to the Soviet atomic bomb project, Riehl was awarded a Stalin Prize (first class), a Lenin Prize, and the Hero of Socialist Labor medal. As part of the awards, he was also given a Dacha west of Moscow; but he did not accept the dacha because he wanted to keep personal distance from the soviets and to return to his homeland. For work at Plant No. 12, Riehl's colleagues Wirths and Thieme were awarded a Stalin Prize and the Order of the Red Banner of Soviet Labor, also known and the Order of the Red Flag.^[41][42][43]

Return to Germany edit

In 1954, the Deutsche Demokratische Republik (DDR, German Democratic Republic) and the Soviet Union prepared a list of scientists they wished to keep in the DDR, due to their having worked on projects related to the Soviet atomic bomb project; this list was known as the "A-list". On this A-list were the names of 18 scientists, dominated by members of the Riehl group, which worked at Plant No. 12 in Ehlektrostal'.^[44][45][46]

While Riehl's work for the Soviet Union netted him significant prestige and wealth, his primary motivation for leaving Russia was freedom. Riehl arrived in East Germany on 4 April 1955; however, by early June he had fled to West Germany. Once there, he joined Heinz Maier-Leibniz on his nuclear reactor staff at Technische Hochschule München, where he made contributions, starting in 1957, to the nuclear facility Forschungsreaktor München (FRM). In 1961 he became an ordinarius professor of technical physics there and concentrated his research activities on solid state physics, especially the physics of ice and optical spectroscopy of solids.^[47][48]

Riehl and his wife Ilse, had two daughters, Ingeborg (oldest) and Irene.^[49] Riehl had a son who had died of natural causes and was buried in Germany.^[50]

The majority of these literature citations have been garnered by searching on variations of the author's name on Google, Google Scholar, the Energy Citations Database.

• Russian Alsos

• History – Technische Hochschule München