In May of 1946 Dr. Louis Slotin, a Manhattan Project scientist, died of severe radiation sickness caused by plutonium. Slotin was engaged in an experiment called tickling the dragon's tail in which two beryllium-coated plutonium hemispheres were brought together in close proximity. The combined mass of the two hemispheres equaled the critical mass required to initiate a fission chain-reaction; that is, if they touched. The idea was to come as close as possible without touching. Slotin was holding the top hemisphere with his left hand when the screw driver separating them slipped. The room was filled with a blue glow and a massive emission of neutrons.
Slotin immediately pulled the hemispheres apart but still received a fatal dose of radiation. He died nine agonizing days later. His left hand swelled up, developed severe blisters, and gangrene shortly after the incident. Doctors kept it packed in ice rather than amputating it. Slotin was thirty-five at the time of the tragic incident.