 At Los Alamos , Bradbury became head of E @-@ 5 , the Implosion Experimentation Group , which put him in charge of the implosion field test program . In August , the laboratory 's director , Robert Oppenheimer , implemented a sweeping reorganisation . E @-@ 5 became part of George Kistiakowsky 's new Explosives Division ( X Division ) , and was renumbered X @-@ 1 . At this point , Bradbury was leading some of the most critical work at the laboratory , as it struggled with the jets that spoiled the perfect spherical shape desired for the implosion process . These were examined with a combination of magnetic , X @-@ ray and RaLa techniques . 
