The Demon Core earned its name through two tragic accidents during the Manhattan Project.

In 1945, physicist Harry Daghlian accidentally dropped a tungsten carbide brick onto the core during a criticality experiment. The resulting radiation burst proved fatal, and he died 25 days later.

In 1946, Louis Slotin was using a screwdriver to hold beryllium reflectors apart when it slipped, causing a supercritical reaction. He died nine days later from radiation exposure.

These tragedies highlighted the dangers of nuclear experimentation and ended hands-on criticality tests forever.