What was the Demon Core? Physics Gone Wrong
The story of the "Demon Core" is one of the most haunting and cautionary tales in the history of nuclear physics. This 6.2 kg sphere of plutonium became infamous for the two deadly accidents it was involved in, leading to the deaths of two physicists, Harry Daghlian and Louis Slotin, in 1945 and 1946 respectively.
*First Accident: Harry Daghlian (August 21, 1945)*
Harry Daghlian was a 24-year-old physicist working on the Manhattan Project. On that fateful day in August 1945, Daghlian was conducting an experiment to determine the critical mass of the plutonium core. To do this, he was placing tungsten carbide bricks around the core to reflect neutrons back into it, a method used to increase its reactivity. As more reflectors are added, the core approaches criticality, where it can sustain a nuclear chain reaction.
During the experiment, Daghlian accidentally dropped a tungsten carbide brick onto the core, which caused it to go supercritical, meaning it began an uncontrolled chain reaction. The core emitted a burst of ionizing radiation, and although Daghlian quickly removed the brick, he had already received a lethal dose of radiation. He developed severe radiation burns and radiation sickness, succumbing to his injuries 25 days later.
*Second Accident: Louis Slotin (May 21, 1946)*
Less than a year after Daghlian's death, the same plutonium core claimed another life. Louis Slotin, a Canadian physicist, was conducting a similar criticality experiment, often referred to as "tickling the dragon's tail." In this experiment, Slotin was using a beryllium shell, which also acted as a neutron reflector, to bring the core closer to criticality. He used a screwdriver to separate the two halves of the beryllium shell, effectively controlling the reaction. However, during the experiment, the screwdriver slipped, causing the two halves to come together fully, and the core went supercritical.
The room was instantly flooded with a burst of intense radiation. Slotin, standing closest to the core, absorbed a fatal dose. He knew immediately what had happened and tried to minimize the exposure of others in the room. He would later describe a "sour taste" in his mouth and a sensation of heat, common symptoms of acute radiation exposure. Slotin died nine days later from severe radiation poisoning.
After these two tragic incidents, the plutonium core was no longer used for such dangerous experiments. Instead, it was melted down and used in other nuclear tests. These accidents served as grim reminders of the lethal power of nuclear materials and the fine line scientists walked during the development of nuclear weapons. The "Demon Core" became a symbol of the dangers of pushing the boundaries of scientific experimentation too far.
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