 Norris Edwin Bradbury ( 30 May 1909 – 20 August 1997 ) , was an American physicist who served as Director of the Los Alamos National Laboratory for 25 years from 1945 to 1970 . He succeeded Robert Oppenheimer , who personally chose Bradbury for the position of director after working closely with him on the Manhattan Project during World War II . Bradbury was in charge of the final assembly of " the Gadget " , detonated in July 1945 for the Trinity test . 
