Compton asked theoretical physicist J. Robert Oppenheimer of the University of California, Berkeley, to take over research into fast neutron calculations—the key to calculations of critical mass and weapon detonation—from Gregory Breit, who had quit on 18 May 1942 because of concerns over lax operational security.
Compton pediulle ó físico teórico Robert Oppenheimer, da Universidade de California, que tomase o relevo na investigación sobre os cálculos de neutróns rápidos—a chave para os cálculos da masa crítica e da detonación das armas—de Gregory Breit, que resignara o 18 de maio de 1942 preocupado pola laxa seguridade operacional.