美國通 36 美國為世界人才匯集之地，參考三位女性的證言：諾貝爾獎物理得主physics laureate Donna Stricklan (她說的故事與管理學大師 Peter Drucker 之妻的回憶錄類似)；Illustrious Immigrants: The Intellectual Migration from Europe, 1930-41: Fermi, Laura:諾貝爾獎物理得主Enrico Fermi 之妻著作；

 

美國通 36  美國為世界人才匯集之地，參考三位女性的證言：諾貝爾獎物理得主physics laureate Donna Stricklan (她說的故事與管理學大師 Peter Drucker 之妻的回憶錄類似)；Illustrious Immigrants: The Intellectual Migration from Europe, 1930-41: Fermi, Laura:諾貝爾獎物理得主Enrico Fermi 之妻著作； 

More than 25 scientists involved in the Manhattan Project went on to win or already had a Nobel Prize. 

Chicago Pile-1 Participants Manhattan Project 

49 scientists and workers witnessed Chicago Pile-1, the world's first controlled, self-sustaining nuclear chain reaction, going critical on December 2, 1942. Four years later, 15 of those participants posed for an iconic photograph on the steps of Eckhart Hall at the University of Chicago. Below is a list of the men and women in that image, along with their years of birth and death. It is followed by a full list of the people who were present when CP-1 went critical. 

Left to right, back row:

Norman Hilberry, 1899-1986

Samuel Allison, 1900-1965

Thomas Brill, 1920-1998

Robert Nobles, 1917-2007

Warren Nyer, 1922-2016

Marvin Wilkening, 1918-2006 

Left to right, middle row:

Harold Agnew, 1921-2013

William Sturm, 1918-1999

Harold Lichtenberger, 1920-1993

Leona Woods, 1919-1986

Leo Szilard, 1898-1964 

Left to right, front row:

Enrico Fermi, 1901-1954

Walter Zinn, 1907-2000

Albert Wattenberg, 1917-2007

Herbert Anderson, 1914-1988 

One of the most important branches of the Manhattan Project was the Metallurgical Laboratory at the University of Chicago. Known simply as the "Met Lab,” the laboratory’s primary role was to design a viable method for plutonium production. Starting in 1939, a team of scientists, including Enrico Fermi, Leo Szilard, Walter Zinn, and Herbert Anderson, conducted experiments at Columbia University using chain-reacting nuclear “piles” to measure the neutron emission from fission. Production was moved to the Met Lab in February 1942 with the goal to produce a self-sustaining nuclear reaction. This experimental proof could then serve as a model for large-scale plutonium production.

Construction 

An abandoned squash court underneath Stagg Field in the middle of the University of Chicago campus was chosen as the test site for the experiment. It was selected after reassurances from Fermi that the probability of an accident was minimal. Nevertheless, the scientists could not be sure they could control the reaction. When asked what he would do if anything went wrong, Fermi replied, “I will walk away – leisurely” (Rhodes 436).

In the freezing cold, workers and scientists built the pile by stacking layers of graphite bricks on top of a crude wood framing. 

The bars had to be cut exactly to fit closely together. Some were drilled with holes to fit lumps of uranium inside, and were alternated with regular “dead uranium” graphite bricks. Others were drilled to fit 14-foot cadmium “control rods” which, when removed, would cause the reaction to go critical.

Construction was finished on December 1, 1942. 771,000 pounds of graphite were used to build 57 layers. The pile also used 80,590 pounds of uranium oxide and 12,400 pounds of uranium metal, approximately $1 million worth of materials.

Going Critical

On December 2, 1942, Fermi and the other scientists watched from a balcony while the last scientist on the floor, George Weil, methodically pulled out the cadmium rods as instructed by Fermi.

The cadmium rods absorbed neutrons and acted as a brake on the nuclear reaction. Using Geiger counters, the scientists closely monitored the value k of the reaction, the effective neutron multiplication factor, which is the average number of neutrons from fission that will cause another reaction. A high enough measurement would indicate that the reaction could sustain itself.

After a break for lunch, Fermi ordered Weil to pull the final cadmium rod out of the pile another 12 inches. Fermi told Arthur Holly Compton, “This is going to do it. Now it will become self-sustaining.” (Rhodes 439) Sure enough, the pile went critical, creating the world’s first self-sustaining chain reaction. It demonstrated a k value of 1.0006, and was allowed to reach a thermal output of 0.5 watts (ultimately it operated at 200 watts maximum). 

Physicist Herbert Anderson recalled:

At first you could hear the sound of the neutron counter, clickety-clack, clickety-clack. Then the clicks came more and more rapidly, and after a while they began to merge into a roar; the counter couldn’t follow anymore. That was the moment to switch to the chart recorder. But when the switch was made, everyone watched in the sudden silence the mounting deflection of the recorder’s pen. It was an awesome silence. Everyone realized the significance of that switch; we were in the high intensity regime and the counters were unable to cope with the situation anymore. Again and again, the scale of the recorder had to be changed to accommodate the neutron intensity which was increasing more and more rapidly. Suddenly Fermi raised his hand. “The pile has gone critical,” he announced. No one present had any doubt about it (Rhodes 440).

After less than 5 minutes, Fermi ordered that the reactor be shut off. Eugene Wigner broke out a bottle of Bertolli Chianti he had been saving for the celebration. The scientists drank it out of paper cups and afterwards they all signed the straw wrapping on the bottle. Forty-nine scientists and workers witnessed the historic event.

A few hours later, Arthur Compton, the director of the Met Lab, called his boss at Harvard, James Conant. “Jim, you’ll be interested to know that the Italian navigator has just landed in the New World,” he said. 

“Were the natives friendly?” asked Conant.

“Everyone landed safe and happy,” Compton replied (Rhodes 442).

Legacy

The Chicago Pile-1 Reactor was soon disassembled and rebuilt with concrete radiation-protecting shielding at the nearby Argonne Laboratory as Chicago Pile-2. The experiment not only proved that nuclear energy could generate power, but also showed a viable method to produce plutonium. Large -scale reactors, including the X-10 Graphite Reactor at Oak Ridge and the B Reactor at Hanford, were subsequently built with Chicago Pile-1 as a model.

Although Stagg Field would be demolished in 1957, a plaque commemorating Chicago Pile-1 was dedicated for its 5th anniversary. The plaque, which remains there to this day, reads, “On December 2, 1942, man achieved here the first self-sustaining chain reaction and thereby initiated the controlled use of nuclear energy.”

For the 25th anniversary in 1967, British sculptor Henry Moore erected a bronze sculpture on the site of Stagg Field titled “Nuclear Energy.” Moore commented, “Like anything that is powerful, it has a power for good and evil... the lower part [of the sculpture] is more architectural and in my mind has the kind of interior of a cathedral with sort of a hopefulness for mankind.” 

Today, the site of Chicago Pile-1 is a Chicago Landmark and a National Historic Landmark.

http://atomicheritage.org/history/chicago-pile-1?fref=gc 

https://ahf.nuclearmuseum.org/ahf/key-documents/chicago-pile-1-participants/?fref=gc&fbclid=IwAR3YtIEvJv7CNVKlACEWv5tBQ_9f0CII9N1UByHne95GQYQyzxKfjCvhP5A

#cp

Enrico Fermi 之妻著作

Illustrious Immigrants: The Intellectual Migration from Europe, 1930-41: Fermi, Laura:

Nobel Prize 

"So many times in my life I heard my mother talk about how she wished she had gone into science or mathematics. She was always sure that she would have found university easier taking the subjects that she had been very good at while in high school. People discouraged her when she was young because they felt women just didn’t go into those disciplines. I think hearing her story of regret made me determined to pick a career in a field I was good at and enjoyed, regardless of what others thought or said. I was very clear in my own head about where my strengths were and what I wanted to do."

- physics laureate Donna Strickland

Learn more about Strickland's life and journey to the Nobel Prize in her biography: https://bit.ly/36Ey8dR

#NobelPrize #WomenInScience

所有心情：

902902