The demonstration began on the afternoon of May 21, 1946, at a secret laboratory tucked into a canyon some three miles from Los Alamos, New Mexico, the birthplace of the atom bomb. Louis Slotin, a Canadian physicist, was showing his colleagues how to bring the exposed core of a nuclear weapon nearly to the point of criticality, a tricky operation known as “tickling the dragon’s tail.” The core, sitting by itself on a squat table, looked unremarkable—a hemisphere of dull metal with a nub of plutonium sticking out of its center, the whole thing warm to the touch because of its radioactivity. It had been quickly molded into shape after the bombing of Nagasaki, to be used in another attack on Japan, then reallocated when it turned out not to be needed for the war effort. At that time, Slotin was perhaps the world’s foremost expert on handling dangerous quantities of plutonium. He had helped assemble the first atomic weapon, barely a year earlier, and a contemporary photograph shows him standing beside its innards with his shirt unbuttoned and sunglasses on, cool and collected. Back then, the bomb was a handmade, artisanal product.
[…]
Slotin called his parents in Winnipeg, who were flown out to New Mexico on the Army’s dime. They arrived four days after the accident. On the fifth day, Slotin’s white-blood-cell count dropped dramatically. His temperature and pulse began to fluctuate. “From this day on, the patient failed rapidly,” the medical report noted. Slotin suffered nausea and abdominal pain and began losing weight. He had internal radiation burns—what one medical expert called a “three-dimensional sunburn.” By the seventh day, he was experiencing periods of “mental confusion.” His lips turned blue and he was put in an oxygen tent. Eventually, he sank into a coma. He died nine days after the accident, at the age of thirty-five. The cause was recorded as acute radiation syndrome, also known as radiation sickness. His body was shipped to Winnipeg for burial in a sealed Army casket.
[…]
Slotin was one of only two people to die from radiation exposure at Los Alamos while the laboratory was under military control. In those early years, from 1943 to 1946, there were about two dozen other deaths—truck and tractor accidents, inadvertent weapons discharges, a suicide, a drowning, a fall from a horse. Four of the fatalities were just bad luck, involving a group of janitors who shared muscatel wine that was laced with antifreeze. But only Slotin and his co-worker Harry Daghlian, Jr., succumbed to the special hazards of the Manhattan Project. Three months to the day before Slotin’s accident, Daghlian had been working with the very same plutonium core, performing a different criticality experiment that used tungsten-carbide blocks instead of the beryllium tamper. He dropped one of the blocks, and the core briefly went critical. Daghlian took nearly a month to die.
After Slotin’s botched demonstration, Los Alamos halted all further criticality work. It was always known to be dangerous—Enrico Fermi himself had warned Slotin that he would be “dead within a year” if he continued—but the exigencies of the Second World War had privileged expediency over safety. Handcrafted critical masses could be modified quickly and on the fly. But by the time Slotin died, such speed was no longer necessary. The Cold War, in spite of its many anxieties, could be taken at a more steady pace. A memo written soon after the accident suggested that future experiments should use remote controls and make “more liberal use of the inverse-square law”—the fact that a little bit of distance goes a long way in decreasing radiation exposure.
[…]
Prior to the accident, officials at Los Alamos expected to send the core to Bikini Atoll, in the Marshall Islands, where it would be detonated in front of thousands of observers as part of Operation Crossroads, the first postwar series of nuclear tests. (Slotin planned to go to Bikini, too, and then take up a teaching position at the University of Chicago when the test series was finished.) After the accident, though, the core was still radioactive enough that it needed time to cool off. It was slated for use in the third test at Crossroads, but the test was cancelled. Records from Los Alamos indicate that the core ultimately met with an anticlimactic fate: in the summer of 1946, it was melted down and recast into a new weapon.
