Editors note: (here is some of the history behind the project at Stagg Field)


The incident
at Stagg Field

by MIKE MOORE

On December 2, 1942, the world changed, though hardly anyone knew it. In a squash court under the abandoned West Stands of Stagg Field at the University of Chicago, a handful of men and one woman achieved the first controlled release of atomic energy. The story of that day has been told often in books, articles, and on film. Arthur Holly Compton, a Nobel laureate and cosmic-ray physicist at the University of Chicago who headed the chain-reaction project, later said the experiment ushered in "a new age." But in almost the same breath, he described the experiment with a "pile" of graphite and uranium as "only an incident."

Compton, one of the world's great scientists, was not confused. He was getting at a vital but poorly understood point: The symbolic meaning of the first manmade self-sustaining nuclear chain reaction far outdistanced its experimental meaning. Something distinctly new had been accomplished December 2. Nevertheless, it was not quite the "birth of the atomic age," as so many have suggested over the years. Nor was it the pivotal moment in the atomic bomb project.

As a piece of science, the December 2 experiment was one milestone in an already sprawling and multifaceted project geared toward producing an atomic bomb in time to affect the outcome of World War II.

In September 1939, Hitler's air and ground forces eviscerated Poland as easily as a hunter might gut a deer. England and France quickly declared war. Prematurely, said many in the United States. Hitler's invasion of Poland constituted a "phony war." Now that Poland had fallen and Hitler had acquired additional "living space" on his eastern frontier, an uneasy calm would return to Europe-if England and France would act with prudence, and if the United States would hold its fire. The United States must remain neutral.

A handful of scientists in the West-emigrés from Germany and Hungary and other European nations that had taken on fascist trappings-would have no part of such isolationist nonsense. They had seen the Nazis and, in Italy, the fascists close up. They believed that Hitler and his tag-along, Mussolini, intended to build a new order on a foundation of bones and blood. German technology and industry would assist Hitler. But German science could prove even more decisive. It might produce a superweapon-a uranium bomb. With that, a Third Reich could be created- and maintained.

In late 1938, German scientists had demonstrated that when uranium, the heaviest natural element, was bombarded with neutrons slowed by a "moderator," some of the uranium atoms would split into two lighter elements. Niels Bohr, among others, noted that considerable energy-although thus far on a laboratory scale-was released in the process. The tight-knit world of nuclear scientists was set abuzz. By the end of 1939, nearly a hundred scholarly papers dealing with nuclear fission had been published, and many physicists had come to believe that if the energy released by fissioning could be controlled, a new source of power would become available.

Fission power could be benign. It might drive generators that would bring electricity-charged abundance to the world. But three Hungarians then living in the United States- Leo Szilard, Eugene Wigner, and Edward Teller-believed that Hitler's scientific stars were rather more likely to produce a bomb. In the summer of 1939, they asked Albert Einstein, a pacifist, to call nuclear energy to the attention of President Franklin D. Roosevelt.

Although no longer on the cutting edge of physics, and wholly oblivious to the recent ferment over fission, Einstein was the world's most famous scientist. His name carried weight. It was "conceivable," Einstein wrote FDR, that uranium could be fashioned into "extremely powerful bombs of a new type."

The President's Advisory Committee on Uranium was formed in October, under the leadership of Lyman J. Briggs, director of the National Bureau of Standards. Although Briggs quickly came to believe that nuclear energy was a promising field of research, he was near retirement and, in any event, not given to boldness. He provided little leadership in the nation's embryonic nuclear program.

For nearly a year and a half after the formation of the committee, nuclear research remained almost wholly uncoordinated. It was largely conducted on a small scale at universities from the Atlantic (Columbia) to the Pacific (the University of California at Berkeley). Although little government funding was forthcoming, the universities were often relatively generous in underwriting their own projects.

Progress in understanding nuclear physics was rapid. By early 1941, it was well understood that if enough refined natural uranium of high purity-a "critical mass"-could be brought together in one place and with the right arrangement, and if the neutrons emitted by the fissioning uranium could be slowed by a moderator such as graphite, additional fissioning would occur on such a scale that a self-sustaining chain reaction would take place.

It was further understood that uranium 238, the most common isotope of uranium, would not sustain a chain reaction. Rather, uranium 235, an isotope associated with 238 at a ratio of one to 139, would get the job done by emitting more neutrons than it absorbed. Finally, it had become clear to a few physicists that if a workable bomb could be made, it would be made with kilogram quantities of uranium 235. Rather than employ "slow" neutrons, a bomb would rely on unmoderated "fast" neutrons to produce a near-instantaneous chain reaction.

But separating uranium 235 from 238 was a daunting theoretical and technical task. They were so similar in atomic structures that obtaining uranium 235 in anything other than microscopic quantities presented staggering technical problems.

By the spring of 1941, key members of the Roosevelt administration anticipated that the United States would shortly go to war, and military preparations were increasing at a rapid pace. Research, development, and production priorities had to be set and then rigidly enforced. Nuclear science was intriguing, but financial and intellectual capital could not be wasted on intensive research and development in any field unless there was a high probability that it would help win the coming war. Unless nuclear science could pass that test, it would go to a back burner until after the war.

In April 1941, Vannevar Bush, under whose leadership America's vast but disparate scientific enterprise was being organized for war, asked the National Academy of Sciences (NAS) to evaluate the short-term military usefulness of nuclear energy. The University of Chicago's Compton chaired the NAS committee charged with the task. By fall, Compton's answer was that a bomb of "superlatively destructive power" possibly could be produced within three to five years. His report supported, at least in broad outline, the conclusions of British scientists, who were lobbying their American colleagues to build a uranium bomb.

By December 6, 1941, the eve of Pearl Harbor, a decision had been made: the United States would forge ahead on atomic-bomb research at a greatly accelerated rate. The final decision to go flat out on developing and building the bomb was made six months later, months before the Chicago pile achieved criticality.

The atomic bomb work defined what would be called today a "fast-track" project. Key elements were planned and financial commitments were made long before the theoretical and developmental work had been completed.

By early 1942, Harold Urey at Columbia University was directing a rapidly expanding program to separate uranium 235 from 238 through gaseous diffusion. Eger V. Murphree, a vice president of Standard Oil Development Co., was supervising an effort that would separate the isotopes with mechanical centrifuges. At the University of California at Berkeley, Ernest Lawrence concentrated on isotope separation through electromagnetic means, a program that eventually produced the calutron, a Lawrence-ism inspired by combining the words California and university with his own cherished invention, the cyclotron.

Meanwhile, Compton had been charged by Vannevar Bush with designing the bomb itself (a task that was soon to be taken up by J. Robert Oppenheimer) while developing something wholly new-the making of a new transuranic element called "plutonium" in a production reactor.

The uranium experiments that had been conducted by Leo Szilard and Enrico Fermi at Columbia since 1939 had been designed principally to explore the properties of uranium 235. But once researchers working elsewhere learned that neutron bombardment turned a portion of uranium 238 into 239-which quickly decayed to neptunium 239 and then to plutonium 239-a second route to producing a bomb opened up. Plutonium had fissioning properties similar to uranium 235, making it a candidate to form the explosive core of an atom bomb.

By the summer of 1942, there were, as Compton liked to say, "four horses in the race." A bomb might ultimately be fashioned around uranium 235, which would be separated from uranium 238 either by gaseous diffusion, by centrifuging, or by Lawrence's electromagnetic process. Alternatively, a bomb might be made with a core of plutonium that had been produced in a chain-reacting pile and then separated chemically.

It would have been reasonable for Compton to have based his plutonium project at Columbia or Princeton or Berkeley, schools at which sophisticated work in nuclear physics had already begun. But Compton chose his own school, the University of Chicago, which was only beginning to explore the field. Chicago had lab space, bright students, and it was far from the coasts, which might eventually be attacked. In his book, Atomic Quest, Compton recalls Lawrence's reaction to that decision:

"You'll never get the chain reaction going here. The whole tempo of the University of Chicago is too slow."

Compton bet Lawrence that a chain reaction would be accomplished by the end of the year. The stakes: a five-cent cigar. Compton won, with nearly a month to spare.

The Metallurgical Laboratory (Met Lab) was established at the university in February 1942. Although it was initially staffed by a small crew, it grew quickly. At its peak, the Met Lab employed about 5,000 people scattered among 70 research groups around the country. But despite the project's size and complexity, it's likely that most people think first of one man: Enrico Fermi, a Nobel laureate who had arrived in the United States in January 1939 with his family, refugees from fascist Italy.

Although Fermi's research interests were broad, for several years in Italy he had focused on the nature of artificial radioactivity and the effect that neutron bombardment had on various elements. He would continue his work at Columbia University, where he was joined, in an often uneasy partnership, by Szilard. When Compton moved the Fermi-Szilard chain-reacting pile project to Chicago in early 1942, Fermi did not complain. Szilard, however, protested, often and loudly; he liked New York better than Chicago.

Albert Wattenberg, a young man when he worked with Fermi on building the first self-sustaining pile (see page 40), had enormous respect for Fermi's accomplishments. Apparently, so did all of Fermi's colleagues. They were in awe of his science; he was clearly a frontrunner in nuclear physics, if not the point man. In preparing for a talk earlier this year at a meeting of the American Association for the Advancement of Science, Wattenberg checked the indexes of four physics texts. "Einstein," said Wattenberg, "averaged about six references per book, and Niels Bohr, who was the father of atomic theory, only four. Fermi averaged 16."

Fermi had a prodigious memory, and not just for numbers. He was said to have memorized long sections of the Divine Comedy and other books of poetry. But it was in his work that his mental powers seemed most startling. Says Wattenberg: "During the war when we were working together, I probably measured the cross-sections for about 70 different elements [to discover their ability to absorb neutrons]. In the course of discussions, when something came up, Fermi remembered, off the top of his head, all of the values of those cross-sections."

But perhaps the characteristic that most endeared Fermi to his colleagues and assistants was that, unlike Szilard, he did not mind getting his hands dirty. William Sturm, who after the war became a researcher and administrator at Oak Ridge and Argonne National Laboratories, was a 24-year-old graduate student at the University of Chicago when he met Fermi.

Sturm was about to be inducted into the army. His job would be to join the bustling and vital Anglo-American radar-development team in England. Sturm visited Compton, his dean, to say goodbye. Compton said that, yes, radar was important, but that Enrico Fermi had just arrived on campus and he was looking for some good people to work with him on an exciting project. Why not look Fermi up?

Sturm dashed around the physics department, asking where Fermi could be found. He was finally directed to the department's machine shop. "I saw a few students and machinists I knew," recalls Sturm. "And across the room was a big band saw with big clouds of black dust coming from it. That was Fermi. He was sawing graphite."

Fermi seemed to be expecting Sturm. He stopped his work, sat down on a window sill, and for five or 10 minutes matter-of-factly laid out what he proposed to do at Chicago. The team he was putting together would first develop a self-sustaining chain reaction in a graphite-moderated uranium pile. If possible, they would then design a plutonium-production reactor that would generate fissile material for bombs.

As secrecy and "compartmentalization" later enveloped the mushrooming multi-site atomic bomb project, such a free-wheeling "uncleared" discussion would have been nearly impossible to imagine, much less to engage in.

But in the spring of 1942, Fermi was focused on the careful, step-by-step process that would be needed if the United States was to actually make a device that might end the war. The first major step was to assemble a chain-reacting pile and make it "go."

Today, after more than 40 years of a nuclear arms race, it's difficult to recreate the idealistic spirit that animated the original bomb project. If anyone should have such terrible weapons, reasoned scientists like Albert Einstein, Leo Szilard, Eugene Wigner, Edward Teller, Enrico Fermi, J. Robert Oppenheimer, Ernest Lawrence, Arthur Holly Compton, and-eventually- thousands more, it should be the United States, not Nazi Germany.

After the conclusion of the December 2 experiment, Wigner produced a bottle of Chianti that he had tucked away in a brown paper bag. Chianti was appropriate, Wigner said later, because Fermi was Italian. "Even though our hearts were by no means light when we sipped our wine around Fermi's pile," Wigner wrote in 1962, "our fears were undefined, like the vague apprehensions of a man who has done something bigger than he ever expected to."

Some 33 months after the group had finished off the Chianti bottle, bombs "of a new type" fell on two Japanese cities, chosen principally because they had not yet been destroyed by Gen. Curtis Lemay's strategic bombing campaign. Being relatively intact, Hiroshima and Nagasaki would clearly show the effects of the new devices.

One bomb had a fissile heart of uranium 235, the other of plutonium. Upwards of 100,000 men, women and children died, some instantly, others in the minutes and hours and weeks and years that followed. The Japanese quickly sued for peace.