University of Chicago, and the University of California, Berkeley. To remove disagreement and duplication, Compton transferred the scientists to the Metallurgical Laboratory at Chicago. Teller was left behind at first, because while he and Mici were now American citizens, they still had relatives in enemy countries. In early 1943, the Los Alamos Laboratory was established in Los Alamos, New Mexico to design an atomic bomb, with Oppenheimer as its director. Teller moved there in March 1943. Apparently, Teller managed to annoy his neighbors there by playing the piano late in the night. Teller became part of the Theoretical (T) Division. He was given a secret identity of Ed Tilden. He was irked at being passed over as its head; the job was instead given to Hans Bethe. Oppenheimer had him investigate unusual approaches to building fission weapons, such as autocatalysis, in which the efficiency of the bomb would increase as the nuclear chain reaction progressed, but proved to be impractical. He also investigated using uranium hydride instead of uranium metal, but its efficiency turned out to be "negligible or less". He continued to push his ideas for a fusion weapon even though it had been put on a low priority during the war (as the creation of a fission weapon proved to be difficult enough). On a visit to New York, he asked Maria Goeppert-Mayer to carry out calculations on the Super for him. She confirmed Teller's own results: the Super was not going to work. A special group was established under Teller in March 1944 to investigate the mathematics of an implosion-type nuclear weapon. It too ran into difficulties. Because of his interest in the Super, Teller did not work as hard on the implosion calculations as Bethe wanted. These too were originally low-priority tasks, but the discovery of spontaneous fission in plutonium by Emilio Segrè's group gave the implosion bomb increased importance. In June 1944, at Bethe's request, Oppenheimer moved Teller out of T Division, and placed him in charge of a special group responsible for the Super, reporting directly to Oppenheimer. He was replaced by Rudolf Peierls from the British Mission, who in turn brought in Klaus Fuchs, who was later revealed to be a Soviet spy. Teller's Super group became part of Fermi's F Division when he joined the Los Alamos Laboratory in September 1944. It included Stanislaw Ulam, Jane Roberg, Geoffrey Chew, Harold and Mary