The Manhattan Project that built the atomic bomb wasn't without its own dangers. Experiments on a so-called "demon core" of plutonium caused the deaths of two Manhattan Project physicists. Both ...

Less than a year later, on May 21, 1946, Louis Slotin would become the demon core’s second victim. Slotin, a 35-year-old physicist, was performing another test to verify how close to criticality the ...