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Louis Slotin

Louis Slotin (December 1, 1910May 30, 1946) was a Canadian-born physicist/chemist who took part in the Manhattan Project. He died of massive radiation poisoning after a criticality accident at Los Alamos.

Louis Slotin was born December 1, 1910 in Winnipeg, Canada, to a family of Israel and Sonia Slotin, Yiddish-speaking refugees from Russia. He was the eldest of the three children. Slotin received his Bachelor of Science degree from the University of Manitoba in 1932 and Master of Science degree in 1933. He went to King's College, London University where he received a doctorate in physical chemistry in 1936. To his friends back home, he managed to give an impression that he had fought for the Spanish Republic and flown with Royal Air Force.

In 1937 Slotin tried to obtain a job with Canada's National Research Council but was not accepted. The University of Chicago accepted him as a research associate later in the year. The job was paid poorly and Slotin's father had to support him for two years. On December 2, 1942, he was around during the start-up of "Chicago Pile 1", the first man-made nuclear reactor created by Enrico Fermi, but there are conflicting accounts of him being actually present at the event.

In 1942, through professor William D. Harkins of the University of Chicago, Slotin got involved with the Manhattan Project, the Allied program to develop the first nuclear weapons. In December 1944 he moved to the Los Alamos laboratory in New Mexico to work in the bomb physics group of R.F. Bacher. Technically, he got a leave-of-absence from the University of Chicago.

At Los Alamos, Slotin's duties consisted of criticality testing, first with Otto Frisch's uranium experiments, and then with plutonium cores. Criticality testing involved dangerous experiments to bring masses of fissile materials to near-critical levels to establish experimentally their critical mass values. Some sources have erroneously claimed that he was involved with triggering devices.

After the war, Slotin's work was still required in the Los Alamos because, as he said, "I am one of the few people left here who are experienced bomb putter-togetherers." He looked forward to resuming his research into biophysics and radiobiology at the University of Chicago and was training a replacement, Alvin C. Graves. He received US citizenship in 1946.

In May 1946, Slotin, among others, was in a laboratory doing an experiment that involved creation of the beginning of the fission reaction by bringing two half-spheres of beryllium-coated plutonium close to each other. The experiment was nicknamed "tickling the dragon's tail" after a remark by Richard Feynman that it was "tickling the tail of a sleeping dragon" due to its flirtations with nuclear chain reaction. Slotin maintained the separation of the half-spheres by a blade of a screwdriver because he apparently distrusted automatic safety mechanisms.

Nine months previously on August 21, 1945, the same cores had produced a burst of ionizing radiation and caused a lethal radiation poisoning to Harry Daghlian, one of the experimenters.

On May 21, the screwdriver slipped, the two hemispheres touched and created a burst of hard radiation . The "blue glow" of air ionization was observed and a "heat wave" was felt by the scientists in the room. Slotin's instant reaction was to separate the masses by hand, by flipping the upper one to the floor. While he succeeded in ending the critical reaction and shielding seven other observers in the room, he exposed himself to a lethal dose (around 2100 rems) of neutron and gamma radiation, in history's second criticality accident. In addition to the blue glow and heat, Slotin experienced a sour taste in his mouth and an intense burning sensation in his left hand. As soon as Slotin left the building, he vomited, a common reaction from exposure to extremely intense ionizing radiation.

Slotin's colleagues rushed him to hospital but Slotin was aware of his condition and realizing he would die is said to have remarked: "You'll be OK, but I think I'm done for." His parents were informed and a number of volunteers wanted to donate blood but the efforts proved futile. The accident ended all hands-on assembly work at Los Alamos. The incident was at first classified.

Louis Slotin died nine days later on May 30, in the presence of his parents. Two of the other observers also died a couple of years later with symptoms of radiation poisoning.

Louis Slotin was buried in Winnipeg on June 2, 1946 (though not in a lead coffin, as was later rumored). In 1948, Slotin's colleagues at Los Alamos and the University of Chicago initiated the Louis A. Slotin Memorial Fund for lectures on physics. It lasted until 1962.

External link


  • Dexter Masters - The Accident (1955)
  • Fat Man and Little Boy (1989 movie) - the character of Michael Merriman (played by John Cusack) is based on Slotin
Last updated: 08-07-2005 19:55:32
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