This sculpture by Henry Moore marks the site at the University of Chicago where Metallurgical Laboratory scientists created the world's first self-sustaining nuclear chain reaction.

The Metallurgical Laboratory or "Met Lab" at the University of Chicago was part of the World War II–era Manhattan Project, created by the United States to develop an atomic bomb. The University of Chicago is a private co-educational university located in Chicago, Illinois. ... Mushroom cloud from the nuclear explosion over Nagasaki rising 18 km (over 11 miles) into the air. ... Control panels and operators for calutrons at the Y-12 Plant in Oak Ridge, Tennessee. ... The mushroom cloud of the atomic bombing of Nagasaki, Japan, 1945, rose some 18 km (11 mi) above the epicenter. ...

History

In July 1939, at the urging of physicists Eugene Wigner and Leó Szilárd, Albert Einstein sent a letter to President Franklin Delano Roosevelt explaining the military potential of nuclear fission and calling for the United States to develop atomic weapons before Nazi Germany did. 1939 was a common year starting on Sunday (link will take you to calendar). ... The word physicist should not be confused with physician, which means medical doctor. ... Eugene Wigner (left) and Alvin Weinberg Eugene Paul Wigner (Hungarian Wigner Pál Jenő) (November 17, 1902 – January 1, 1995) was a Hungarian physicist and mathematician. ... Leó Szilárd (right) and Albert Einstein re-enact the signing of the famous letter to Franklin Delano Roosevelt. ... Albert Einstein (March 14, 1879 – April 18, 1955) was a German theoretical physicist who is widely regarded as the greatest scientist of the 20th century. ... Franklin Delano Roosevelt (January 30, 1882–April 12, 1945), 32nd President of the United States, the longest-serving holder of the office and the only man to be elected President more than twice, was one of the central figures of 20th century history. ... Sketch of induced nuclear fission, a neutron (n) strikes a uranium nucleus which splits into similar products (F. P.), and releases more neutrons to continue the process, and energy in the form of gamma and other radiation. ... Nazi Germany, or the Third Reich, commonly refers to Germany in the years 1933–1945, when it was under the firm control of the totalitarian and fascist ideology of the Nazi Party, with the Führer Adolf Hitler as dictator. ...

In response, Roosevelt appointed a committee to direct the research. Early funding was meager, but in 1940, scientists at Columbia University and the University of California were able to demonstrate the weapons potential of the isotope uranium-235 and the newly-discovered element plutonium. 1940 was a leap year starting on Monday (link will take you to calendar). ... Columbia University is a private university in New York City. ... The University of California (UC) is a public university system within the State of California. ... Isotopes are forms of a chemical element whose nuclei have the same atomic number, Z, but different atomic masses, A. The word isotope, meaning at the same place, comes from the fact that all isotopes of an element are located at the same place on the periodic table. ... Uranium-235 is an isotope of uranium that differs from the elements other common isotope, uranium-238, by its ability to cause a rapidly expanding fission chain reaction. ... The term element can refer to: Chemical element — material that consists of atoms with the same number of protons in the nucleus (see also Periodic table). ... General Name, Symbol, Number Plutonium, Pu, 94 Chemical series Actinides Period, Block 7, f Density, Hardness 19816 kg/m3, no data Appearance silvery white metal Atomic properties Atomic weight 244. ...

Immediately after the Japanese attack on Pearl Harbor on December 7, 1941, Nobel Prize laureate Arthur H. Compton quickly gained support for consolidating plutonium research at Chicago and for an ambitious schedule that called for producing the first atomic bomb in January 1945, a goal that was missed by only six months. Satellite image of Pearl Harbor. ... December 7 is the 341st day (342nd on leap years) of the year in the Gregorian calendar. ... 1941 was a common year starting on Wednesday (link will take you to calendar). ... Photographs of Nobel Prize Medals. ... Arthur Holly Compton (September 10, 1892 – March 15, 1962) won the Nobel Prize in Physics (1927) for discovery of the effect named after him. ... 1945 was a common year starting on Monday (link will take you to calendar). ...

"Metallurgical Laboratory" was the "cover" name given to Compton's facility. Its objectives were to produce chain-reacting "piles" of uranium to convert to plutonium, find ways to separate the plutonium from the uranium and to design a bomb. A chain reaction is a sequence of reactions where a reactive product or biproduct causes more additional reactions. ...

In August 1942, a team of scientists under Glenn T. Seaborg isolated the first weighable amount of plutonium from uranium irradiated in cyclotrons. Meanwhile, work continued under the renowned Italian physicist Enrico Fermi to build uranium and graphite piles that could be brought to critical mass in a controlled, self-sustaining nuclear reaction. 1942 was a common year starting on Thursday (link will take you to calendar). ... Glenn Theodore Seaborg (April 19, 1912 – February 25, 1999) was an American atomic scientist. ... Irradiation is the process whereby an item is exposed to radiation. ... 60-inch cyclotron, circa 1939, showing beam of accelerated ions (perhaps protons or deuterons) escaping the accelerator and ionizing the surrounding air causing a blue glow. ... Enrico Fermi (September 29, 1901 – November 28, 1954) was an Italian physicist most noted for his work on beta decay, the development of the first nuclear reactor, and for the development of quantum theory. ... Graphite (named by Abraham Gottlob Werner in 1789, from the Greek γραφειν: to draw/write, for its use in pencils) is one of the allotropes of carbon. ... San Francisco Critical Mass, 29th April, 2005. ... In nuclear physics, a nuclear reaction is a process in which two nuclei or nuclear particles collide, to produce products different to the initial products. ...

A labor strike prevented the construction of the piles at a laboratory in the Argonne forest preserve, so Fermi and his associates Martin Whittaker and Walter Zinn set about building the piles (really the world's first "nuclear reactor," although that term was not used until 1952) in a racquets court under the abandoned west stands of the university’s Alonzo Stagg Field. The piles consisted of uranium pellets as a neutron–producing "core" separated from one another by graphite blocks to slow the neutrons. Fermi himself described the apparatus as "a crude pile of black bricks and wooden timbers." The controls consisted of cadmium-coated rods that absorbed neutrons. Withdrawing the rods would increase neutron activity in the pile to lead to a self-sustaining chain reaction. Re-inserting the rods would dampen the reaction. Argonne National Laboratory is one of the United States governments oldest and largest science and engineering research national laboratories and is the largest in the Midwest. ... Nuclear power station at Leibstadt, Switzerland. ... 1952 was a leap year starting on Tuesday (link will take you to calendar). ... Racquets (also Rackets or Hard Racquets) is a game played in a 30 foot by 60 foot enclosed court, using a long wooden racquet and a small, hard ball. ... Stagg Field was a stadium in Chicago, Illinois. ... Properties In physics, the neutron is a subatomic particle with no net electric charge and a mass of 939. ... General Name, Symbol, Number Cadmium, Cd, 48 Chemical series Transition metals Group, Period, Block 12, 5, d Density, Hardness 8650 kg/m3, 2 Appearance Silvery gray metallic Atomic properties Atomic weight 112. ...

On December 2, 1942, Chicago Pile 1 (CP-1) was ready for a demonstration. Before a group of dignitaries, a young scientist named George Weil worked the final control rod while Fermi carefully monitored the neutron activity. The pile went critical at 3:20 p.m. Fermi shut it down 33 minutes later. In 1943, he rebuilt the pile as CP-2 at the Argonne Laboratory. December 2 is the 336th day (337th on leap years) of the year in the Gregorian calendar. ... 1942 was a common year starting on Thursday (link will take you to calendar). ... 1943 is a common year starting on Friday. ...

The stadium was demolished in 1957. The location is commemorated as the Site of the First Self-Sustaining Nuclear Reaction, a National Historic Landmark, featuring a sculpture by Henry Moore. The USS Arizona Memorial. ... Reclining Figure (1951) is characteristic of Moores sculptures, with an abstract female figure intercut with voids. ...

External links

• The First Pile (http://hep.uchicago.edu/cp1.html) by Corbin Allardice and Edward R. Trapnell
• Manhattan Project Signature Facilities (http://ma.mbe.doe.gov/me70/history/met_lab.htm)
• Oak Ridge National Laboratory Review (http://www.ornl.gov/info/ornlreview/rev25-34/chapter1.shtml)
• Chicago Pile 1 Pioneers (http://www.anl.gov/Science_and_Technology/History/cp1list.html)