a pact. The pact was a pledge that whoever first made contact with the Soviets would speak for the rest. The objectives of their pact were threefold: (1) Prevent plunder of their institutes, (2) Continue their work with minimal interruption, and (3) Protect themselves from prosecution for any political acts of the past. Before the end of World War II, Thiessen, a member of the Nazi Party, had Communist contacts. On 27 April 1945, Thiessen arrived at von Ardenne's institute in an armored vehicle with a major of the Soviet Army, who was also a leading Soviet chemist. All four of the pact members were taken to the Soviet Union. Hertz was made head of Institute G, in Agudseri (Agudzery), about 10 km southeast of Sukhumi and a suburb of Gul’rips (Gulrip’shi); Volmer was initially assigned to Hertz's institute. Topics assigned to Gustav Hertz's Institute G included: (1) Separation of isotopes by diffusion in a flow of inert gases, for which Gustav Hertz was the leader, (2) Development of a condensation pump, for which Justus Mühlenpfordt was the leader, (3) Design and build a mass spectrometer for determining the isotopic composition of uranium, for which Werner Schütze was the leader, (4) Development of frameless (ceramic) diffusion partitions for filters, for which Reinhold Reichmann was the leader, and (5) Development of a theory of stability and control of a diffusion cascade, for which Heinz Barwich was the leader; Barwich had been deputy to Hertz at Siemens. Von Ardenne was made head of Institute A, in Sinop, a suburb of Sukhumi. Late in January 1946, Volmer was assigned to the Nauchno-Issledovatel’skij Institut-9 (NII-9, Scientific Research Institute No. 9), in Moscow. Volmer was given a design bureau to work on the production of heavy water; Robert Döpel also worked at NII-9. Volmer's group with Victor Bayerl, a physical chemist and Gustav Richter a physicist, was under Alexander Mikailovich Rosen, and they designed a heavy water production process and facility based on the counterflow of ammonia. The installation was constructed at Norilsk and completed in 1948, after which Volmer's organization was transferred to Zinaida Yershova’s group, which worked on plutonium extraction from fission products. Return to Germany In March 1955, Volmer returned to East Germany. He received the Soviet Union's national prize, first class, Hervorragender Wissenschaftler des Volkes (Outstanding Scientist of the People). On 1 May 1955, he became an ordinarius professor at the