Manhattan Project scientists Death

The Dragon Bites Twice: “Tickling the Tail of the Dragon”

First in August of 1945 and again in May of 1946, two Los Alamos, NM scientists, Harry Daghlian and Louis Slotin, were exposed to lethal doses of radiation while performing experiments to determine critical mass. These experiments, performed at the Omega Site, were commonly referred to as "Tickling the Tail of the Dragon". Although several months apart, both accidents occurred on a Tuesday and both on the 21st of the month, and ultimately both men died in the same hospital room at the U.S. Engineers Hospital at Los Alamos, NM.

On August 21, 1945, Daghlian was working on a criticality experiment, attempting to build a neutron reflector. He was working alone and late at night. While working on the experiment, the neutron counter indicated placing the last brick would cause the assembly to go supercritical. While slowly backing away before placing the tungsten carbide brick, he accidentally dropped it. Already having received the initial blast of neutron radiation, he disassembled the pile, exposing himself to additional gamma radiation. He died 25 days later at the hospital in Los Alamos.

On Tuesday, May 21st, 1946, Louis Slotin was demonstrating a criticality experiment that involved gradually bringing together two beryllium-coated halves of a sphere that held plutonium at its core- without allowing the halves to touch- and recording the increasing rate of fissioning. Then, in one fateful moment, the screwdriver slipped.

A blue glow flashed from the sphere and the Geiger counter clicked furiously. Slotin, exposed to nearly 1, 000 rads of radiation (well above a lethal dose), reacted instinctively and knocked the spheres apart. His action stopped the chain reaction and prevented the seven other individuals in the room from being exposed to the same high levels of radiation as he experienced. Slotin's health rapidly deteriorated and he spent his last nine days receiving around-the-clock care as he went through the ravages of radiation sickness, passing away on May 30th, 1946.

It was not until the second accident and Louis Slotin's death that more rigorous safety procedures were applied. After the incident, criticality experiments at Los Alamos were conducted remotely, with roughly a quarter of a mile separating scientists from radioactive material. Their deaths helped incite a new era of health and safety measures.