 It was named after Jerrold R. Zacharias, its leader until 17 October 1945, when he returned to MIT, and was succeeded by Roger S. Warner.It moved to Sandia Base between March and July 1946, except for its Z-4 (Mechanical Engineering) Group, which followed in February 1947.The number of personnel at the Los Alamos Laboratory plummeted from its wartime peak of over 3,000 to around 1,000, but many were still living in substandard temporary wartime accommodation.