Louis Slotin - Los Alamos

Los Alamos

At Los Alamos, Slotin's duties consisted of dangerous criticality testing, first with uranium in Otto Robert Frisch's experiments, and later with plutonium cores. Criticality testing involved bringing masses of fissile materials to near-critical levels to establish their critical mass values. Scientists referred to this flirting with the possibility of a nuclear chain reaction as "tickling the dragon's tail," based on a remark by physicist Richard Feynman, who compared the experiments to "tickling the tail of a sleeping dragon". On 16 July 1945, Slotin assembled the core for Trinity, the first detonated atomic device, and became known as the "chief armorer of the United States" for his expertise in assembling nuclear weapons.

On 21 August 1945, Harry K. Daghlian, one of Slotin's close colleagues and a laboratory assistant, was performing a critical mass experiment when he accidentally dropped a heavy tungsten carbide brick onto a 6.2 kilograms (14 lb) plutonium-gallium alloy bomb core. The 24-year old Daghlian was irradiated with a large dose of neutron radiation. Later estimates would suggest that this dose might not have been fatal on its own, but he then received additional delayed gamma radiation and beta burns while disassembling his experiment. He quickly collapsed with acute radiation poisoning and died one month later in the Los Alamos base hospital. Famed nuclear physicist Enrico Fermi reacted with a warning to Slotin: "Keep doing that experiment that way and you'll be dead within a year". Slotin was unmoved; he had done the test some forty times already by then.

After the war, Slotin expressed growing disdain for his personal involvement in the project. He remarked, "I have become involved in the Navy tests, much to my disgust." Unfortunately for Slotin, his participation at Los Alamos was still required 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 began training a replacement, Alvin C. Graves, to take over his work once he resumed his peacetime job.

In the 1945-46 winter, Slotin shocked some of his colleagues with a bold action. He repaired an instrument 6 feet under water inside the Clinton Pile while it was operating, rather than wait an extra day for the reactor to be shut down. He did not wear his dosimetry badge, but his dose was estimated to be at least 100 roentgen. A dose of 1 Gy (~100 roentgen) can cause nausea and vomiting in 10% of cases, but is generally survivable.