Thin Man (nuclear bomb) and the name came from the Dashiell Hammett detective novel "The Thin Man" and series of movies by the same name. The "Fat Man" bomb would be round and fat and was named after Sydney Greenstreet's character in "The Maltese Falcon". "Little Boy" would come last and be named only to contrast to the "Thin Man" bomb. Oppenheimer assembled a team at the Los Alamos Laboratory to work on plutonium gun design that included senior engineer Edwin McMillan and senior physicists Charles Critchfield and Joseph Hirschfelder. Critchfield had been working with sabots, which Oppenheimer believed would be required by the
Thin Man (nuclear bomb) Thin Man to achieve the high muzzle velocities that critical assembly would require. Hirschfelder had been working on internal ballistics. Oppenheimer led the design effort himself until June 1943, when Navy Captain William Sterling Parsons arrived and took over the Ordnance and Engineering Division and direct management of the "Thin Man" project. These four created and tested all the elements of the Thin Man design between April 1943 and August 1944. Parsons, who had developed the proximity fuze for the Navy, ran the division, and handled liaison with other agencies. As the head of the E-6 Projectile, Target, and Source