Karl Zimmer

The following was published in Kernphysikalische Forschungsberichte (Research Reports in Nuclear Physics), an internal publication of the German Uranverein. Reports in this publication were classified Top Secret, they had very limited distribution, and the authors were not allowed to keep copies. The reports were confiscated under the Allied Operation Alsos and sent to the United States Atomic Energy Commission for evaluation. In 1971, the reports were declassified and returned to Germany. The reports are available at the Karlsruhe Nuclear Research Center and the American Institute of Physics.

Upon Zimmer's release from the Soviet Union in 1955, he eventually went to West Germany under legal circumstances, where he worked at the Kernforschungszentrum Karlsruhe (Karlsruhe Nuclear Research Center), founded in 1956 and later known as the Forschungszentrum Karlsruhe. He became director of the Instituts für Strahlenbiologie (IStB, Institute for Radiation Biology).

In preparation for release from the Soviet Union, it was standard practice to put personnel into quarantine for a few years if they worked on projects related to the Soviet atomic bomb project, as was the case for Zimmer. Additionally, 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. Nine, possibly 10, of the names were associated with the Riehl group which worked at Plant No. 12 in Ehlektrostal'. Born, Catsch, Riehl, and Zimmer were on the list.

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 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. (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.)

Before being rejoined in the Soviet Union, Zimmer, Timofeev-Resovskij, and Riehl had collaborated on the biological effects of ionizing radiation. Also, Zimmer and Timofeev-Resovskij had put together a manuscript which was a comprehensive summary of their work and that of others on radiation-induced gene mutation and related areas; the book, Das Trefferprinzip in der Biologie, was published in Germany while they were in the Soviet Union. In 1948, due to Lysenkoism, there were grave consequences for the institute in Sungul' in general and for Zimmer and Timofeev-Resovskij in particular. The book was put on a forbidden list and the laboratory was not allowed to conduct research on its topics. Since the book represented many years of Zimmer's life's work, he was rather downcast by the circumstances.

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 a biophysics research department, in which 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.

At the close of World War II, Russia had special search teams operating in Austria and Germany, especially in Berlin, to identify and "requisition" equipment, materiel, intellectual property, and personnel useful to the Soviet atomic bomb project. The exploitation teams were under the Russian Alsos and they were headed by Lavrenij Beria's deputy, Colonel General A. P. Zavenyagin. These teams were composed of scientific staff members, in NKVD officer's uniforms, from the bomb project's only laboratory, Laboratory No. 2, in Moscow. In mid-May 1945, the Russian nuclear physicists Georgy Flerov and Lev Artsimovich, in NKVD colonel's uniforms, compelled Zimmer to take them to the location of Riehl and his staff, who had evacuated their Auergesellschaft facilities and were west of Berlin, hoping to be in an area occupied by the American or British military forces. Riehl was detained at the search team's facility in Berlin-Friedrichshagen for a week. 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. Riehl was to head up a uranium production group at Plant No. 12 in Ehlektrostal' (Электросталь).

From 1945 to 1950, Riehl was in charge of uranium production at Plant No. 12 in Ehlektrostal'. When Riehl learned that Hans-Joachim Born and Karl Zimmer were being held in Krasnogorsk, in the main PoW camp for Germans with scientific degrees, Riehl arranged though Zavenyagin to have them sent to Ehlektrostal'. Alexander Catsch was also sent there. At Ehlektrostal', Riehl had a hard time incorporating Born, Catsch, and Zimmer into his tasking on uranium production, as Born was a radiochemist, Catsch was a physician and radiation biologist, and Zimmer was a physicist and radiation biologist.

Zimmer obtained his doctorate in 1934 with a thesis on photochemistry.

Early on, Zimmer worked as an advisor in radiotherapeutic physics in a radiological hospital and as an employee of Auergesellschaft in Berlin. However, he completed most of his theoretical work at the Kaiser-Wilhelm Gesellschaft's Institut für Hirnforschung (KWIH, Kaiser Wilhelm Institute for Brain Research) in Berlin-Buch. Zimmer worked in N. V. Timofeev-Resovskij's Genetics Department at the KWIH. Timofeev-Resovskij, a citizen of the Soviet Union, worked in Germany starting in 1924, and he stayed even after Adolf Hitler came to power in 1933. Very early in Zimmer's career, in 1935, he published the major work, Über die Natur der Genmutation und der Genstruktur, with Timofeev-Resovskij, and Max Delbrück; it was considered to be a major advance in understanding the nature of gene mutation and gene structure. At Auergesellschaft, Zimmer collaborated with Nikolaus Riehl, director of scientific research at the works.

Karl Günter Zimmer (12 July 1911 – 29 February 1988) was a German physicist and radiation biologist, known for his work on the effects of ionizing radiation on DNA. In 1935, he published the major work, Über die Natur der Genmutation und der Genstruktur, with N. V. Timofeev-Resovskij, and Max Delbrück; it was considered to be a major advance in understanding the nature of gene mutation and gene structure. In 1945, he was sent to the Soviet Union to work on their atomic bomb project. In 1955, he left Russia and eventually went to West Germany.