The "Last Universal Scientist" Takes Charge
In New York City in 1940, Enrico Fermi continued
to conduct nuclear fission experiments at Columbia University. Fermi's team,
including Leo Szilard and Walter Zinn, confirmed that absorption of a neutron
by a uranium nucleus can cause the nucleus to split into two nearly equal
parts, releasing several neutrons and enormous amounts of energy. The potential
for a self-sustaining nuclear chain reaction had become a strong possibility.
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Enrico Fermi, the last universal
scientist. Arthur Compton recalled his visit to Columbia to invite Fermi to
join the Met Lab project: Fermi stepped to the blackboard and worked out
"simply and directly the equation from which could be calculated the critical
size of a chain-reaction sphere." (Click the image to see a larger photo.) |
With the 1938 discovery of nuclear fission, Germany had a two-year head
start on developing nuclear energy; the Americans' fear was that the Nazis
would shape it into a weapon of mass destruction. Germany also had in its grasp
two materials critical to its development -- heavy water and uranium. They were
available in abundance only in Norway and Czechoslovakia, both under Nazi
control. The emigré scientists urged the American scientific community
to explore the potential for nuclear energy. They also urged caution and
secrecy. The early fission experiments had been reported in the newspapers.
Szilard urged American nuclear physicists not to publish their work. Germany
must remain unaware of American progress.
In August 1939, Szilard and fellow Hungarian physicists Eugene Wigner
and Edward Teller urged Albert Einstein to sign a letter they had drafted for
President Roosevelt. Einstein's letter
noted that the work of Fermi and Szilard "leads me to expect that the element
uranium may be turned into a new and important source of energy in the near
future." President Roosevelt responded by appointing an Advisory Committee on
Uranium. The Office of Scientific Research and Development was established on
June 28, 1941, under the direction of Vannevar Bush, to develop atomic energy.
On December 6, the day before the bombing of Pearl Harbor, Roosevelt authorized
the Manhattan Engineering District. The decision to pursue the making of an
atomic bomb had been made.
Bush organized the nuclear fission effort -- code-named the
Metallurgical Project -- into three parts. Harold Urey headed uranium isotope
separation at Columbia. Ernest Lawrence, who had built the first practical
cyclotron, supervised electro-magnetic separation of uranium-235 at Berkeley in
California. Arthur Holly Compton, dean of physics at the University of Chicago,
was put in charge of finding fissionable material at what would be called
Chicago Pile 1 at the Metallurgical Laboratory, or Met Lab.
The task of building a pile for self-sustaining nuclear reaction was
assigned to Fermi, by then considered the "last universal scientist." He was
the perfect man for the job. He had intense personal drive and combined
experimental skill with theoretical talent. He was simple, direct, and had a
passion for clarity. He once said, "If I could remember the names of all these
particles, I'd be a botanist."
Compton recalled his visit to Columbia to invite Fermi into the Met Lab
project: Fermi "stepping to the blackboard... worked out... simply and
directly, the equation from which could be calculated the critical size of a
chain-reaction sphere."
Although uranium and graphite were the materials used at Met Lab, an
actual bomb would need pure fissionable materials -- pure uranium-235 or
plutonium. Work continued on elements beyond uranium and on heavier elements.
In March 1940, Glenn Seaborg (later chairman of the Atomic Energy Commission)
co-discovered the transuranic element 94, plutonium. When it was isolated the
following year, its plutonium-239 isotope promised to be more fissionable than
uranium. Compton, however, believed that electromagnetic separation of
uranium-235, under study at Oak Ridge, would be the fastest route to building a
bomb.
Once control of a self-sustaining nuclear chain reaction became a
probability, other scientific disciplines were brought into the pile project.
Joining the team of physicists were chemists -- including Seaborg and Frank
Spedding -- biologists, engineers, metallurgists, chemical engineers and health
researchers. Compton hired one of his protégés, Norman Hilberry,
as administrative assistant to, among other duties, receive "all kicks intended
for the project leader, and carry through all the unpleasant tasks from which
the project leader wants to escape."
The search for a safe and adequate site for the pilot plant led Compton
to the Palos Hills Forest Preserve, nearly 30 miles southwest of Chicago. A
1,000-acre tract in the Argonne Forest area of the preserve was deemed
appropriate -- it was named Site A. Because of construction difficulties,
however, it was impossible to build experimental piles there. Work on the first
man-made atomic reactor was conducted at the University of Chicago. Space was
found under the unused football stands of Stagg Field, in a converted
squash-racquets court (the Soviets would later translate its name to "pumpkin
field"). On everyone's mind was Germany's leadership in neutron research -- and
the need for utter secrecy. The race for the bomb had been joined.
Next: Piglet and the Pumkin field
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