Demon core
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The Demon core was the nickname given to a 6.2-kilogram (14 lb) spherical subcritical mass of plutonium that accidentally went critical on two separate instances at the Los Alamos laboratory, in 1945 and 1946. Each incident resulted in the acute radiation poisoning and subsequent death of a scientist. After these incidents, the core was referred to as the Demon core.
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[edit] First incident
On August 21, 1945, the plutonium core produced a burst of ionizing radiation that irradiated Harry Daghlian, a physicist who made a mistake while working alone doing neutron reflection experiments on the core. The core was placed within a stack of neutron-reflective bricks, the addition of each brick moved the assembly closer to criticality. Daghlian, while attempting to stack another brick around the assembly, accidentally dropped one of the bricks onto the core causing the assembly to go supercritical. Despite moving the brick off the assembly quickly, Daghlian received a fatal dose of radiation, succumbing 21 days later.
[edit] Second incident
On May 21, 1946, physicist Louis Slotin and other scientists were in a Los Alamos laboratory conducting an experiment that involved creating a fission reaction by placing two half-spheres of beryllium (a neutron reflector) around the same plutonium core. Slotin's hand holding a screwdriver separating the hemispheres slipped, the beryllium neutron reflector hemispheres closed, and the core went supercritical, releasing a very high dose of radiation. He quickly pulled the two halves apart, stopping the chain reaction and hence saving the lives of the seven other men in the laboratory. Louis Slotin himself, however, died 9 days later from acute radiation poisoning. The scientist assisting received sufficient radiation dosage to cause serious injuries and some permanent partial disability, while the others in the room suffered no permanent injuries from the accident.[1]
[edit] The core in use
The Demon core was put to use for the Able test of the Crossroads series on July 1, 1946, demonstrating that the criticality experiments of Daghlian and Slotin increased the efficiency of the weapon.[2]
[edit] Popular culture
The Slotin and Daghlian incidents were combined and fictionalized in the film Fat Man and Little Boy.
[edit] See also
[edit] References
- ^ Trinity Atomic Website, retrieved February 2009
- ^ Miller, Richard L (1991). Under the Cloud: The Decades of Nuclear Testing. The Woodlands, Texas: Two Sixty Press. pp. 69, 77. ISBN 0029216206.
[edit] External Links
- McLaughlin et al. "A Review of Criticality Accidents" by Los Alamos National Laboratory (Report LA-13638), May 2000.
