The demon core (like the core used in the bombing of Nagasaki) was, when assembled, a solid 6.2-kilogram (14 lb) sphere … See more

The core, once assembled, was designed to be at "−6 cents". In this state, there is only a small safety margin against extraneous factors that might increase reactivity, causing the core to become supercritica… See more

On May 21, 1946, physicist Louis Slotin and seven other personnel were in a Los Alamos laboratory conducting another experiment to verify the closeness of the core to criticality by the positioning of neutron refl… See more