摘要：On 21 May, 1946, the Canadian physicist, Louis Slotin, was performing a criticalityexperiment at Los Alamos, New Mexico, the town that had been built to build theatomic bombs dropped on Hiroshima and Nagasaki the year before. Preparations wereunderway for the Operation Crossroads atomic tests in the South Pacific and theplutonium core with which he was working was intended for detonation at BikiniAtoll.1The experiment, so perilous it was described as “tickling the tail of a sleepingdragon” by Richard Feynman (Lustig and Shepherd-Barr, 553), involved bringing thecore to the point of criticality by gradually enclosing it in two halves of a berylliumshell. As the two halves of the shell were brought together, the beryllium reflectedmore and more neutrons back into the core, bringing it progressively closer to a selfsustainingchain reaction. Extraordinarily, all that prevented the shell from closingwas a screwdriver, used by Slotin to hold up the top half of the shell. As it wasgradually lowered, a Geiger counter gave an aural indication of increasingradioactivity.
