May 21, 1946 – Canadian physicist Louis Slotin manually assembled a critical mass of plutonium while demonstrating his technique to visiting scientists at Los Alamos, New Mexico. The device consisted of two half-spheres of beryllium-covered plutonium, which can be moved together slowly to measure the criticality. Normally the device would be operated by machinery, but Slotin distrusted the devices and manually operated it by holding the upper sphere with his thumb inserted in a hole in the top like a bowling ball. In most experiments, a number of washers would be arranged to prevent the two hemispheres from falling together completely, but he had removed them. In order to slowly bring the two pieces together, he rested one edge on the lower sphere and rotated a slot screwdriver between the other edge to control the separation. At one point, the screwdriver slipped and the assembly went critical while he was still holding onto it. None of the seven observers received a lethal dose, but Slotin died on the 30th from massive radiation poisoning, with an estimated dose of 1000 rad, or 10 gray (Gy). This was dramatized in the movie Fat Man and Little Boy, except that the movie placed the event before the Trinity test —in reality, a device that Slotin had helped to assemble.
27 July 2004
survival of the theorists
There are probably many different morals to this story, but I'll take it as endorsement for my non-experimental kind of physics.