Leona Woods

Leona Harriet Woods (August 9, 1919 – November 10, 1986), later known as Leona Woods Marshall and Leona Woods Marshall Libby, was an American physicist who helped build the first nuclear reactor and the first atomic bomb.

At age 23, she was the youngest and only female member of the team which built and experimented with the world's first nuclear reactor (then called a pile), Chicago Pile-1, in a project led by her mentor Enrico Fermi. In particular, Woods was instrumental in the construction and then utilization of geiger counters for analysis during experimentation. She was the only woman present when the reactor went critical. She worked with Fermi on the Manhattan Project, and, together with her first husband John Marshall, she subsequently helped solve the problem of xenon poisoning at the Hanford plutonium production site, and supervised the construction and operation of Hanford's plutonium production reactors.

After the war, she became a fellow at Fermi's Institute for Nuclear Studies. She later worked at the Institute for Advanced Study in Princeton, New Jersey, the Brookhaven National Laboratory, and New York University, where she became a professor in 1962. Her research involved high-energy physics, astrophysics and cosmology. In 1966 she divorced Marshall and married Nobel laureate Willard Libby. She became a professor at the University of Colorado, and a staff member at RAND Corporation. In later life she became interested in ecological and environmental issues, and she devised a method of using the isotope ratios in tree rings to study climate change. She was a strong advocate of food irradiation as a means of killing harmful bacteria.

Leona Woods Marshall Libby
Leona Woods.jpeg
Leona Woods Marshall at the University of Chicago in 1946
BornAugust 9, 1919
La Grange, Illinois, United States
DiedNovember 10, 1986 (aged 67)
Alma materUniversity of Chicago
Known forinvolvement in the Manhattan Project
Scientific career
Doctoral advisorRobert Mulliken
Other academic advisorsStanisław Mrozowski

Early life

Leona Harriet Woods was born on a farm in La Grange, Illinois on August 9, 1919, the second of five children of Weightstill Arno Woods, a lawyer, and his wife Mary Leona Holderness Woods. She had two sisters and two brothers.[1][2] She graduated from Lyons Township High School in La Grange at 14,[1] and received her BS in chemistry from the University of Chicago in 1938, at the age of 18.[2][3]

After passing her qualifying exams in chemistry, she approached the Nobel Prize for Physics laureate James Franck about being his graduate student, having been impressed by a talk he gave in 1939 on Brillouin zones.[4] Franck accepted, but told her that when he was young his professor had warned him that as a Jewish academic, he would starve to death. Franck therefore warned Woods that "You are a woman and you will starve to death."[5] Despite the fact that Franck did not look malnourished, she took the warning seriously, and decided to instead become a graduate student of Robert Mulliken, who would one day become a Nobel laureate himself.[5]

Mulliken allowed her to choose her own research problem, and edited the final version before it appeared in the Physical Review.[5] Her doctoral thesis, "On the Silicon Oxide Bands",[6] prepared under the supervision of Mulliken and Polish chemist Stanisław Mrozowski was accepted in 1943.[2] Mulliken, she later recalled, had twice told her "that perhaps not all he taught me was wasted."[5] His students, she noted, "agree that this is his highest praise."[5]

Manhattan Project

By 1942, when she was finishing writing up her thesis, she was the youngest and last of Mulliken's pre-war students, and was working alone because all her fellow students had become involved with war work. She met Herbert Anderson, who was working for Enrico Fermi. The two would go swimming together in Lake Michigan every afternoon at 5 pm. Anderson discovered that Woods was adept with vacuum technology from her research, and as soon as her PhD was finished, he hired her to work with the boron trifluoride detectors used to measure neutron flux.[7]

Fermi's group constructed a nuclear reactor known as Chicago Pile-1 under the stands of Stagg Field, the University's abandoned football stadium, where Woods had once played squash. Walter Zinn did not want a woman involved in the dirty work of placing the graphite blocks, but Woods had plenty of work to do with the detectors and thermocouples, and used a small stack of graphite of her own to measure the effects of a radium-beryllium source on manganese foil to obtain a measure of the neutron cross section in order to calibrate the detectors.[8] Woods was the only woman present when the reactor went critical, asking Fermi "When do we become scared?"[9]

In this 1946 photo of the Chicago pile team, Woods is the only woman, fourth from the left in the middle row.

Laura Fermi remembered Woods as "a tall young girl built like an athlete, who could do a man's job and do it well. She was the only woman physicist in Enrico's group. At that time, her mother, who was also endowed with inexhaustible energy, was running a small farm near Chicago almost by herself. To relieve Mrs. Woods of some work, Leona divided her time between atoms and potatoes."[10]

Like many scientists working on the project, Woods affected a casual attitude towards the danger posed by radiation. After a morning with Willard Libby soldering a canister containing a mixture of radium salt and beryllium metal, Woods absorbed about 200 roentgens, and her white blood cell count halved. The doctors gave her a lecture on how a woman has only a fixed number of egg cells, a proposition that Woods was skeptical of. She considered that the important thing was that the solder was done correctly.[11] When the team moved to their new home at Argonne, Woods had a dormitory all to herself.[12]

Woods married John Marshall in July 1943. Soon after, she fell pregnant. While she told Enrico Fermi, they agreed not to let Walter Zinn know, for fear that he would insist that she leave the reactor building. She covered up her pregnant belly with her baggy denim work clothes.[13] She rode to work each day on an unheated Army bus, "arriving each morning barely in time to vomit before starting the day's work."[14] The child, a boy called Peter, was born in 1944.[2] She returned to work a few days later.[13]

A team from Argonne was on hand for powering up the first reactor at the Hanford Site, where large reactors would produce plutonium for bombs. They watched the reactor in shifts, with John Marshall and others on the day shift, Enrico Fermi and Leona Marshall on the night shift, ending at midnight, and Don Hughes and John Wheeler on the swing shift.[15] While the Marshalls were babysitting the reactor in Hanford, they left Peter with Leona's mother.[16]

The reactor was powered up successfully, but after a few hours the power level dropped and the reactor shut down. Leona speculated that a water leak was the problem, rather than a radioactive poison. However, during the night the operators were able to power the reactor up again only to have it once more die away. The timings now pointed to a radioactive poison. After working through the numbers with slide rules and hand calculators, they determined the neutron cross section of the poison, which turned out to be xenon-135. Fortunately, the DuPont engineers had equipped the reactor with 50 per cent more fuel tubes than the physicists had called for, and by loading them up, they managed to get the reactor started.[15]

Asked many years later about how she felt about her involvement in the Manhattan Project, she said:

I think everyone was terrified that we were wrong (in our way of developing the bomb) and the Germans were ahead of us. That was a persistent and ever-present fear, fed, of course, by the fact that our leaders knew those people in Germany. They went to school with them. Our leaders were terrified, and that terror fed to us. If the Germans had got it before we did, I don't know what would have happened to the world. Something different. Germany led in the field of physics. In every respect, at the time war set in, when Hitler lowered the boom. It was a very frightening time.

I certainly do recall how I felt when the atomic bombs were used. My brother-in-law was captain of the first minesweeper scheduled into Sasebo Harbor. My brother was a Marine, with a flame thrower on Okinawa. I'm sure these people would not have lasted in an invasion. It was pretty clear the war would continue, with half a million of our fighting men dead not to say how many Japanese. You know and I know that General (Curtis) LeMay firebombed Tokyo and nobody even mentions the slaughter that happened then. They think Nagasaki and Hiroshima were something compared to the firebombing.


I have no regrets. I think we did right, and we couldn't have done it differently. Yeah. I know it has been suggested the second bomb, Nagasaki, was not necessary. The guys who cry on shoulders, when you are in a war, to the death, I don't think you stand around and ask, "Is it right?"[17]

Post-war career

After the war, Leona Marshall returned to the University of Chicago, where she became a fellow at Fermi's Institute for Nuclear Studies.[2][18] Working with the Chicago Pile 3 heavy water reactor, she found a way to 100 percent spin polarize neutron beams, and determined the refractive index of neutrons for various materials.[19] Her second child, John Marshall III, was born in 1949.[2] She became an assistant professor in 1953.[18]

After Fermi died in 1954, the Marshalls separated. John Marshall returned to the Los Alamos Laboratory, while Leona, now effectively a single mother,[2] became a fellow at the Institute for Advanced Study in Princeton, New Jersey in 1957.[18] The following year she became a fellow at the Brookhaven National Laboratory, at a time when the focus of research in physics was shifting away from the nucleus and towards elementary particles. In 1960, she joined New York University as an associate professor of physics. She became a professor in 1962.[2]

Three years later, she became a professor at the University of Colorado, researching high-energy physics, astrophysics and cosmology. She then became a staff member at RAND Corporation, where she worked until 1976. In 1966, she divorced John Marshall, and married Willard Libby, who had won the Nobel prize in 1960. She later joined him at UCLA, where she became a visiting professor of environmental studies, engineering, engineering archaeology, mechanical aerospace and nuclear engineering in 1973.[2][18]

Now known as Leona Marshall Libby, she became interested in ecological and environmental issues, and she devised a method of using the isotope ratios of Oxygen-18 to Oxygen-16, Carbon-13 to Carbon-12, and Deuterium to Hydrogen in tree rings to study changes in temperature and rainfall patterns hundreds of years before records were kept, opening the door to the study of climate change.[18][20]

Like Willard Libby, she was a strong advocate of food irradiation as a means of killing off harmful bacteria, and advocated that legal and regulatory restrictions on its use be relaxed.[21] She proposed that, instead of it being sprayed with malathion, fruit affected by the Mediterranean fruit fly could be treated with gamma rays.[22]

She was a prolific author, publishing over 200 scientific papers.[22] While at RAND she wrote a paper on Creation of an Atmosphere for the Moon (1969). Her works include the autobiographical The Uranium People (1979), a history of early atomic research. After Libby died in 1980, she edited his papers with Rainer Berger, and published The Life Work of Nobel Laureate Willard Libby (1982). Her last paper, on quasi-stellar objects, appeared in 1984.[2][18]

She died at St. John's Medical Center in Santa Monica, California, on November 10, 1986,[22] from an anesthesia-induced stroke.[23] She was survived by her sons Peter and John, and four grandchildren.[22] She also had two stepdaughters, Janet Eva Libby and Susan Charlotte Libby from her second marriage.[1]

Selected bibliography

  • Libby, L., M. (1969) Creation of an atmosphere for the moon. Rand Corporation.
  • Libby, L., M. (1970) Fifty environmental problems of timely importance. Rand Corporation.
  • Libby, L., M. (1979) The Uranium People. Crane, Russak.
  • Libby, L., M. (1980) The upside down cosmology and the lack of solar neutrinos.
  • Libby, L., M. (1982) Life Work of Nobel Laureate Willard Frank Libby.
  • Libby, L., M. (1982) Carbon Dioxide and Climate. Pergamon.
  • Libby, L., M. (1983) Past Climates: Tree Thermometers, Commodities, and People. Texas: University of Texas.


  1. ^ a b c "Leona Woods". Soylent Communications. Retrieved April 15, 2013.
  2. ^ a b c d e f g h i j Ware & Braukman 2004, pp. 385–387.
  3. ^ Libby 1979, pp. 28–29.
  4. ^ Libby 1979, p. 29.
  5. ^ a b c d e Libby 1979, p. 30.
  6. ^ Woods, L. H. (June 1943). "On the Silicon Oxide Bands". Physical Review. American Physical Society. 63 (11–12): 426–430. Bibcode:1943PhRv...63..426W. doi:10.1103/PhysRev.63.426.
  7. ^ Libby 1979, p. 85.
  8. ^ Libby 1979, pp. 86–87.
  9. ^ Fermi 1954, p. 197.
  10. ^ Fermi 1954, p. 179.
  11. ^ Libby 1979, p. 155.
  12. ^ Libby 1979, p. 156.
  13. ^ a b Libby 1979, p. 164.
  14. ^ Libby 1979, p. 165.
  15. ^ a b Libby 1979, pp. 181–183.
  16. ^ Sanger & Wollner 1995, p. 162.
  17. ^ Sanger & Wollner 1995, p. 163.
  18. ^ a b c d e f Wayne 2011, pp. 521–622.
  19. ^ Alvarez 1987, p. 118.
  20. ^ Libby, Leona Marshall; Pandolfi, Louis J. (June 1974). "Temperature Dependence of Isotope Ratios in Tree Rings" (PDF). Proceedings of the National Academy of Sciences. 71 (6): 2482–2486. Bibcode:1974PNAS...71.2482L. doi:10.1073/pnas.71.6.2482. PMC 388483. PMID 16592163. Retrieved April 16, 2013.
  21. ^ Black, Edwin F.; Libby, Leona Marshall (June–July 1983). "Commercial Food Irradiation". Bulletin of the Atomic Scientists. 39 (6): 48–50. Retrieved April 16, 2013.
  22. ^ a b c d Folkart, Burt A. (November 13, 1986). "Leona Marshall Libby Dies; Sole Woman to Work on Fermi's 1st Nuclear Reactor". Retrieved April 16, 2013.
  23. ^ "The Chicago Pile 1 Pioneers". Argonne National Laboratory. Retrieved April 23, 2013.


  • Alvarez, Luis (1987). Alvarez: Adventures of a Physicist. Basic Books. ISBN 0-465-00115-7.
  • Fermi, Laura (1954). Atoms in the Family: My Life with Enrico Fermi. Chicago, Illinois: University of Chicago Press. OCLC 537507.
  • Libby, Leona Marshall (1979). The Uranium People. New York: Crane, Russak. ISBN 0-8448-1300-1. OCLC 4665032.
  • Sanger, S. L.; Wollner, Craig (1995). Working on the Bomb: an Oral History of WWII Hanford. Portland, Oregon: Portland State University. ISBN 0-87678-115-6. OCLC 34034740.
  • Wayne, Tiffany K. (2011). American Women of Science since 1900 Vol. 2, I-Z. Santa Barbara, California: ABC-CLIO. ISBN 1-59884-158-0. OCLC 775854668.
  • Ware, Susan; Braukman, Stacy Lorraine (2004). Notable American Women: a Biographical Dictionary Completing the Twentieth Century. Cambridge, Massachusetts: Belknap Press. ISBN 0-674-01488-X. OCLC 56014756.

External links

Chicago Pile-1

Chicago Pile-1 (CP-1) was the world's first nuclear reactor. On 2 December 1942, the first human-made self-sustaining nuclear chain reaction was initiated in CP-1, during an experiment led by Enrico Fermi. The secret development of the reactor was the first major technical achievement of the Manhattan Project, the Allied effort to create atomic bombs during World War II. Although the project's civilian and military leaders had misgivings about the possibility of a disastrous runaway reaction, they nevertheless decided due to time pressure to carry out the experiment in a densely populated area. It was built by the Metallurgical Laboratory at the University of Chicago, under the west viewing stands of the original Stagg Field. Fermi described the apparatus as "a crude pile of black bricks and wooden timbers".The reactor was assembled in November 1942, by a team that included Fermi, Leo Szilard (who had previously formulated an idea for non-fission chain reaction), Leona Woods, Herbert L. Anderson, Walter Zinn, Martin D. Whitaker, and George Weil. Because the enrichment of uranium had not yet begun at the Oak Ridge site, the reactor used natural uranium rather than uranium enriched in isotope 235. This required a very large amount of material in order to reach criticality, along with graphite used as a neutron moderator. The reactor contained 45,000 ultra-pure graphite blocks weighing 360 tons, and was fueled by 5.4 tons of uranium metal and 45 tons of uranium oxide. Unlike most subsequent nuclear reactors, it had no radiation shielding or cooling system as it operated at very low power – about one-half watt.

The success of the reactor provided the first vivid demonstration of the feasibility of the military use of nuclear energy by the Allies, and the reality of the danger that Nazi Germany would succeed in producing nuclear weapons and win the war with them. Previously, estimates of critical masses had been crude calculations, leading to order-of-magnitude uncertainties about the size of a hypothetical bomb. The successful use of graphite as a moderator paved the way for progress in the Allied effort, whereas the German program languished partly because of the belief that scarce and expensive heavy water would have to be used for that purpose.

In 1943, CP-1 was moved to Red Gate Woods, and reconfigured to become Chicago Pile-2 (CP-2). There, it was operated until 1954, when it was dismantled and buried. The stands at Stagg Field were demolished in August 1957; the site is now a National Historic Landmark and a Chicago Landmark.

Clinton Engineer Works

The Clinton Engineer Works (CEW) was the production installation of the Manhattan Project that during World War II produced the enriched uranium used in the 1945 bombing of Hiroshima, as well as the first examples of reactor-produced plutonium. It consisted of production facilities arranged at three major sites, various utilities including a power plant, and the town of Oak Ridge. It was in East Tennessee, about 18 miles (29 km) west of Knoxville, and was named after the town of Clinton, eight miles (13 km) to the north. The production facilities were mainly in Roane County, and the northern part of the site was in Anderson County. The Manhattan District Engineer, Kenneth Nichols, moved the Manhattan District headquarters from Manhattan to Oak Ridge in August 1943. During the war, Clinton's advanced research was managed for the government by the University of Chicago.

Construction workers were housed in a community known as Happy Valley. Built by the Army Corps of Engineers in 1943, this temporary community housed 15,000 people. The township of Oak Ridge was established to house the production staff. The operating force peaked at 50,000 workers just after the end of the war. The construction labor force peaked at 75,000 and the combined employment peak was 80,000. The town was developed by the federal government as a segregated community; black residents lived only in an area known as Gamble Valley, in government-built "hutments" (one-room shacks) on the south side of what is now Tuskegee Drive.

Edgar Sengier

Edgar Sengier (9 October 1879 – 26 July 1963) was a Belgian businessman and director of the Union Minière du Haut Katanga mining company that operated in Belgian Congo during World War II.

Sengier is credited with giving the American government access to much of the uranium necessary for the Manhattan Project, much of which was already stored in a Staten Island warehouse due to his foresight to stockpile the ore to prevent it from falling into a possible enemy's hands.

For his actions, he became the first non-American civilian to be awarded the Medal for Merit by the United States government.

Glenn T. Seaborg

Glenn Theodore Seaborg (; April 19, 1912 – February 25, 1999) was an American chemist whose involvement in the synthesis, discovery and investigation of ten transuranium elements earned him a share of the 1951 Nobel Prize in Chemistry. His work in this area also led to his development of the actinide concept and the arrangement of the actinide series in the periodic table of the elements.

Seaborg spent most of his career as an educator and research scientist at the University of California, Berkeley, serving as a professor, and, between 1958 and 1961, as the university's second chancellor. He advised ten US Presidents – from Harry S. Truman to Bill Clinton – on nuclear policy and was Chairman of the United States Atomic Energy Commission from 1961 to 1971, where he pushed for commercial nuclear energy and the peaceful applications of nuclear science. Throughout his career, Seaborg worked for arms control. He was a signatory to the Franck Report and contributed to the Limited Test Ban Treaty, the Nuclear Non-Proliferation Treaty and the Comprehensive Test Ban Treaty. He was a well-known advocate of science education and federal funding for pure research. Toward the end of the Eisenhower administration, he was the principal author of the Seaborg Report on academic science, and, as a member of President Ronald Reagan's National Commission on Excellence in Education, he was a key contributor to its 1983 report "A Nation at Risk".

Seaborg was the principal or co-discoverer of ten elements: plutonium, americium, curium, berkelium, californium, einsteinium, fermium, mendelevium, nobelium and element 106, which, while he was still living, was named seaborgium in his honor. He also discovered more than 100 atomic isotopes and is credited with important contributions to the chemistry of plutonium, originally as part of the Manhattan Project where he developed the extraction process used to isolate the plutonium fuel for the second atomic bomb. Early in his career, he was a pioneer in nuclear medicine and discovered isotopes of elements with important applications in the diagnosis and treatment of diseases, including iodine-131, which is used in the treatment of thyroid disease. In addition to his theoretical work in the development of the actinide concept, which placed the actinide series beneath the lanthanide series on the periodic table, he postulated the existence of super-heavy elements in the transactinide and superactinide series.

After sharing the 1951 Nobel Prize in Chemistry with Edwin McMillan, he received approximately 50 honorary doctorates and numerous other awards and honors. The list of things named after Seaborg ranges from the chemical element Seaborgium to the asteroid 4856 Seaborg. He was a prolific author, penning numerous books and 500 journal articles, often in collaboration with others. He was once listed in the Guinness Book of World Records as the person with the longest entry in Who's Who in America.

Index of physics articles (L)

The index of physics articles is split into multiple pages due to its size.

To navigate by individual letter use the table of contents below.

La Grange, Illinois

The village of La Grange () (often spelled LaGrange), a suburb of Chicago, is a village in Cook County, in the U.S. state of Illinois. The population was 15,550 at the 2010 census.

List of female scientists in the 20th century

This is a historical list, intended to deal with the time period when women working in scientific fields were rare. For this reason, this list deals only with the 20th century. Some women who primarily worked in the 19th or 21st centuries may appear in a different list.

List of geological features on Venus

This is a list of geological features on Venus. Venus is the second planet from the Sun. Venus is classified as a terrestrial planet and it is sometimes called Earth's "sister planet" owing to their similar size, gravity, and bulk composition (Venus is both the closest planet to Earth and the planet closest in size to Earth). The surface of Venus is covered by a dense atmosphere and presents clear evidence of former violent volcanic activity. It has shield and composite volcanoes similar to those found on Earth.

Lyons Township High School

Lyons Township High School (often referred to as LTHS or simply LT) is a public high school located in Western Springs, Illinois (South Campus), and also in La Grange, Illinois (North Campus). Lyons Township is a co-educational high school and serves grades 9–12 for Lyons Township High School District 204. Students from the communities of LaGrange, Western Springs, Burr Ridge, La Grange Park, Countryside, Indian Head Park, Hodgkins, and parts of Brookfield, Willow Springs, and McCook attend Lyons Township. Lyons Township High School is the 8th-largest public high school in Illinois and the 46th-largest public high school in the United States. Freshmen and sophomores attend class at South campus, located at 4900 S. Willow Springs Rd. in Western Springs. Juniors and seniors attend class at North campus, located at 100 S. Brainard Ave. in LaGrange, which also houses the district offices. Sports facilities at Lyons Township include swimming pools, field houses, theatres, a turf football field (south campus), soccer fields, baseball fields, a gym, outdoor tracks, basketball courts, and volleyball courts. The two campuses are about a mile apart. Activity buses run after school between the campuses.

Manhattan Project

The Manhattan Project was a research and development undertaking during World War II that produced the first nuclear weapons. It was led by the United States with the support of the United Kingdom and Canada. From 1942 to 1946, the project was under the direction of Major General Leslie Groves of the U.S. Army Corps of Engineers. Nuclear physicist Robert Oppenheimer was the director of the Los Alamos Laboratory that designed the actual bombs. The Army component of the project was designated the Manhattan District; Manhattan gradually superseded the official codename, Development of Substitute Materials, for the entire project. Along the way, the project absorbed its earlier British counterpart, Tube Alloys. The Manhattan Project began modestly in 1939, but grew to employ more than 130,000 people and cost nearly US$2 billion (about $23 billion in 2018 dollars). Over 90% of the cost was for building factories and to produce fissile material, with less than 10% for development and production of the weapons. Research and production took place at more than 30 sites across the United States, the United Kingdom, and Canada.

Two types of atomic bombs were developed concurrently during the war: a relatively simple gun-type fission weapon and a more complex implosion-type nuclear weapon. The Thin Man gun-type design proved impractical to use with plutonium, and therefore a simpler gun-type called Little Boy was developed that used uranium-235, an isotope that makes up only 0.7 percent of natural uranium. Chemically identical to the most common isotope, uranium-238, and with almost the same mass, it proved difficult to separate the two. Three methods were employed for uranium enrichment: electromagnetic, gaseous and thermal. Most of this work was performed at the Clinton Engineer Works at Oak Ridge, Tennessee.

In parallel with the work on uranium was an effort to produce plutonium. After the feasibility of the world's first artificial nuclear reactor was demonstrated in Chicago at the Metallurgical Laboratory, it designed the X-10 Graphite Reactor at Oak Ridge and the production reactors in Hanford, Washington, in which uranium was irradiated and transmuted into plutonium. The plutonium was then chemically separated from the uranium, using the bismuth phosphate process. The Fat Man plutonium implosion-type weapon was developed in a concerted design and development effort by the Los Alamos Laboratory.

The project was also charged with gathering intelligence on the German nuclear weapon project. Through Operation Alsos, Manhattan Project personnel served in Europe, sometimes behind enemy lines, where they gathered nuclear materials and documents, and rounded up German scientists. Despite the Manhattan Project's tight security, Soviet atomic spies successfully penetrated the program.

The first nuclear device ever detonated was an implosion-type bomb at the Trinity test, conducted at New Mexico's Alamogordo Bombing and Gunnery Range on 16 July 1945. Little Boy and Fat Man bombs were used a month later in the atomic bombings of Hiroshima and Nagasaki, respectively. In the immediate postwar years, the Manhattan Project conducted weapons testing at Bikini Atoll as part of Operation Crossroads, developed new weapons, promoted the development of the network of national laboratories, supported medical research into radiology and laid the foundations for the nuclear navy. It maintained control over American atomic weapons research and production until the formation of the United States Atomic Energy Commission in January 1947.

Project Y

The Los Alamos Laboratory, also known as Project Y, was a secret laboratory established by the Manhattan Project and operated by the University of California during World War II. Its mission was to design and build the first atomic bombs. Robert Oppenheimer was its first director, from 1943 to December 1945, when he was succeeded by Norris Bradbury. In order to enable scientists to freely discuss their work while preserving security, the laboratory was located in a remote part of New Mexico. The wartime laboratory occupied buildings that had once been part of the Los Alamos Ranch School.

The development effort initially concentrated on a gun-type fission weapon using plutonium called Thin Man. In April 1944, the Los Alamos Laboratory determined that the rate of spontaneous fission in plutonium bred in a nuclear reactor was too great due to the presence of plutonium-240 and would cause a predetonation, a nuclear chain reaction before the core was fully assembled. Oppenheimer then reorganized the laboratory and orchestrated an all-out and ultimately successful effort on an alternative design proposed by John von Neumann, an implosion-type nuclear weapon, which was called Fat Man. A variant of the gun-type design known as Little Boy was developed using uranium-235.

Chemists at the Los Alamos Laboratory developed methods of purifying uranium and plutonium, the latter a metal that only existed in microscopic quantities when Project Y began. Its metallurgists found that plutonium had unexpected properties, but were nonetheless able to cast it into metal spheres. The laboratory built the Water Boiler, an aqueous homogeneous reactor, the third reactor in the world to become operational. It also researched the Super, a hydrogen bomb that would use a fission bomb to ignite a nuclear fusion reaction in deuterium and tritium.

The Fat Man design was tested in the Trinity nuclear test in July 1945. Project Y personnel formed pit crews and assembly teams for the atomic bombings of Hiroshima and Nagasaki and participated in the bombing as weaponeers and observers. After the war ended, the laboratory supported the Operation Crossroads nuclear tests at Bikini Atoll. A new Z Division was created to control testing, stockpiling and bomb assembly activities, which were concentrated at Sandia Base. The Los Alamos Laboratory became Los Alamos Scientific Laboratory in 1947.

Willard Libby

Willard Frank Libby (December 17, 1908 – September 8, 1980) was an American physical chemist noted for his role in the 1949 development of radiocarbon dating, a process which revolutionized archaeology and palaeontology. For his contributions to the team that developed this process, Libby was awarded the Nobel Prize in Chemistry in 1960.

A 1927 chemistry graduate of the University of California at Berkeley, from which he received his doctorate in 1933, he studied radioactive elements and developed sensitive Geiger counters to measure weak natural and artificial radioactivity. During World War II he worked in the Manhattan Project's Substitute Alloy Materials (SAM) Laboratories at Columbia University, developing the gaseous diffusion process for uranium enrichment.

After the war, Libby accepted professorship at the University of Chicago's Institute for Nuclear Studies, where he developed the technique for dating organic compounds using carbon-14. He also discovered that tritium similarly could be used for dating water, and therefore wine. In 1950, he became a member of the General Advisory Committee (GAC) of the Atomic Energy Commission (AEC). He was appointed a commissioner in 1954, becoming its sole scientist. He sided with Edward Teller on pursuing a crash program to develop the hydrogen bomb, participated in the Atoms for Peace program, and defended the administration's atmospheric nuclear testing.

Libby resigned from the AEC in 1959 to become Professor of Chemistry at University of California, Los Angeles (UCLA), a position he held until his retirement in 1976. In 1962, he became the Director of the University of California statewide Institute of Geophysics and Planetary Physics (IGPP). He started the first Environmental Engineering program at UCLA in 1972, and as a member of the California Air Resources Board, he worked to develop and improve California's air pollution standards.

William Sterling Parsons

Rear Admiral William Sterling "Deak" Parsons (26 November 1901 – 5 December 1953) was an American naval officer who worked as an ordnance expert on the Manhattan Project during World War II. He is best known for being the weaponeer on the Enola Gay, the aircraft which dropped the Little Boy atomic bomb on Hiroshima, Japan in 1945. To avoid the possibility of a nuclear explosion if the aircraft crashed and burned on takeoff, he decided to arm the bomb in flight. While the aircraft was en route to Hiroshima, Parsons climbed into the cramped and dark bomb bay, and inserted the powder charge and detonator. He was awarded the Silver Star for his part in the mission.

A 1922 graduate of the United States Naval Academy, Parsons served on a variety of warships beginning with the battleship USS Idaho. He was trained in ordnance and studied ballistics under L.T.E. Thompson at the Naval Proving Ground in Dahlgren, Virginia. In July 1933, Parsons became liaison officer between the Bureau of Ordnance and the Naval Research Laboratory. He became interested in radar and was one of the first to recognize its potential to locate ships and aircraft, and perhaps even track shells in flight. In September 1940, Parsons and Merle Tuve of the National Defense Research Committee began work on the development of the proximity fuze, an invention that was provided to US by the UK Tizard Mission, a radar-triggered fuze that would explode a shell in the proximity of the target. The fuze, eventually known as the VT (variable time) fuze, Mark 32, went into production in 1942. Parsons was on hand to watch the cruiser USS Helena shoot down the first enemy aircraft with a VT fuze in the Solomon Islands in January 1943.

In June 1943, Parsons joined the Manhattan Project as Associate Director at the research laboratory at Los Alamos, New Mexico under J. Robert Oppenheimer. Parsons became responsible for the ordnance aspects of the project, including the design and testing of the non-nuclear components of nuclear weapons. In a reorganization in 1944, he lost responsibility for the implosion-type fission weapon, but retained that for the design and development of the gun-type fission weapon, which eventually became Little Boy. He was also responsible for the delivery program, codenamed Project Alberta. He watched the Trinity nuclear test from a B-29.

After the war, Parsons was promoted to the rank of rear admiral without ever having commanded a ship. He participated in Operation Crossroads, the nuclear weapon tests at Bikini Atoll in 1946, and later the Operation Sandstone tests at Enewetak Atoll in 1948. In 1947, he became deputy commander of the Armed Forces Special Weapons Project. He died of a heart attack on 5 December 1953.

Women in science

Women have made significant contributions to science from the earliest times. Historians with an interest in gender and science have illuminated the scientific endeavors and accomplishments of women, the barriers they have faced, and the strategies implemented to have their work peer-reviewed and accepted in major scientific journals and other publications. The historical, critical and sociological study of these issues has become an academic discipline in its own right.

The involvement of women in the field of medicine occurred in several early civilizations, and the study of natural philosophy in ancient Greece was open to women. Women contributed to the proto-science of alchemy in the first or second centuries AD. During the Middle Ages, convents were an important place of education for women, and some of these communities provided opportunities for women to contribute to scholarly research. While the eleventh century saw the emergence of the first universities, women were, for the most part, excluded from university education. The attitude to educating women in medical fields in Italy appears to have been more liberal than in other places. The first known woman to earn a university chair in a scientific field of studies, was eighteenth-century Italian scientist, Laura Bassi.

Although gender roles were largely defined in the eighteenth century, women experienced great advances in science. During the nineteenth century, women were excluded from most formal scientific education, but they began to be admitted into learned societies during this period. In the later nineteenth century, the rise of the women's college provided jobs for women scientists and opportunities for education.

Marie Curie, a physicist and chemist who conducted pioneering research on radioactive decay, was the first woman to receive a Nobel Prize in Physics and became the first person to receive a second Nobel Prize in Chemistry. Forty women have been awarded the Nobel Prize between 1901 and 2010. Seventeen women have been awarded the Nobel Prize in physics, chemistry, physiology or medicine.

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