Alexander Suss Langsdorf Jr. (May 30, 1912 – May 24, 1996) was an American

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate ca ...

on the team that developed the

atomic bomb A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission bomb) or a combination of fission and fusion reactions ( thermonuclear bomb), producing a nuclear explosion. Both bomb ...

and several devices related to nuclear physics. He was a vocal opponent of the use and proliferation of

nuclear weapons A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission bomb) or a combination of fission and fusion reactions ( thermonuclear bomb), producing a nuclear explosion. Both bom ...

.Stout, David (May 26, 1996)
Alexander Langsdorf, 83, Plutonium Pioneer.
''

The New York Times ''The New York Times'' (''the Times'', ''NYT'', or the Gray Lady) is a daily newspaper based in New York City with a worldwide readership reported in 2020 to comprise a declining 840,000 paid print subscribers, and a growing 6 million paid ...

Life and career

Langsdorf was born in

St. Louis, Missouri St. Louis () is the second-largest city in Missouri, United States. It sits near the confluence of the Mississippi and the Missouri Rivers. In 2020, the city proper had a population of 301,578, while the bi-state metropolitan area, whic ...

. He earned an undergraduate degree from

Washington University in St. Louis Washington University in St. Louis (WashU or WUSTL) is a private research university with its main campus in St. Louis County, and Clayton, Missouri. Founded in 1853, the university is named after George Washington. Washington University i ...

in 1932 and a doctorate in physics from

Massachusetts Institute of Technology The Massachusetts Institute of Technology (MIT) is a Private university, private Land-grant university, land-grant research university in Cambridge, Massachusetts. Established in 1861, MIT has played a key role in the development of modern t ...

in 1937. In this time he developed a continuously sensitive cloud chamber. After a research fellowship at the

University of California at Berkeley The University of California, Berkeley (UC Berkeley, Berkeley, Cal, or California) is a public land-grant research university in Berkeley, California. Established in 1868 as the University of California, it is the state's first land-grant uni ...

, he became a physics instructor at Washington University in St. Louis from 1939 to 1942. Prior to

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the World War II by country, vast majority of the world's countries—including all of the great power ...

, Langsdorf co-developed a

cyclotron A cyclotron is a type of particle accelerator invented by Ernest O. Lawrence in 1929–1930 at the University of California, Berkeley, and patented in 1932. Lawrence, Ernest O. ''Method and apparatus for the acceleration of ions'', filed: J ...

for splitting atomic particles at

. It was designed for use in

medical research Medical research (or biomedical research), also known as experimental medicine, encompasses a wide array of research, extending from " basic research" (also called ''bench science'' or ''bench research''), – involving fundamental scienti ...

. During World War II, he worked with

Enrico Fermi Enrico Fermi (; 29 September 1901 – 28 November 1954) was an Italian (later naturalized American) physicist and the creator of the world's first nuclear reactor, the Chicago Pile-1. He has been called the "architect of the nuclear age" an ...

at the

University of Chicago The University of Chicago (UChicago, Chicago, U of C, or UChi) is a private university, private research university in Chicago, Illinois. Its main campus is located in Chicago's Hyde Park, Chicago, Hyde Park neighborhood. The University of Chic ...

on the

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 w ...

. Langsdorf was one of the designers of the first two

nuclear reactor A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction or nuclear fusion reactions. Nuclear reactors are used at nuclear power plants for electricity generation and in nuclear marine propulsion. Heat from nu ...

s after Fermi completed the first sustained nuclear chain reaction in 1942. Langsdorf was able to produce a tiny usable sample of

plutonium Plutonium is a radioactive chemical element with the symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exhib ...

using his device. That sample was then used in the

Trinity nuclear test Trinity was the code name of the first detonation of a nuclear weapon. It was conducted by the United States Army at 5:29 a.m. on July 16, 1945, as part of the Manhattan Project. The test was conducted in the Jornada del Muerto desert abo ...

on July 16, 1945. Langsdorf urged President

Harry S Truman Harry may refer to: TV shows * ''Harry'' (American TV series), a 1987 American comedy series starring Alan Arkin * ''Harry'' (British TV series), a 1993 BBC drama that ran for two seasons * ''Harry'' (talk show), a 2016 American daytime talk show ...

not to use the bomb against the Japanese, but a plutonium-based bomb was dropped on

Nagasaki is the capital and the largest city of Nagasaki Prefecture on the island of Kyushu in Japan. It became the sole port used for trade with the Portuguese and Dutch during the 16th through 19th centuries. The Hidden Christian Sites in th ...

soon after. He continued to urge against expansion of nuclear weapons. He helped found ''

Bulletin of the Atomic Scientists The ''Bulletin of the Atomic Scientists'' is a nonprofit organization concerning science and global security issues resulting from accelerating technological advances that have negative consequences for humanity. The ''Bulletin'' publishes conte ...

'', and his wife

Martyl Langsdorf Martyl Suzanne Schweig Langsdorf (March 16, 1917 – March 26, 2013) was an American artist who created the Doomsday Clock image for the June 1947 cover of the '' Bulletin of the Atomic Scientists''.Yardley, William (April 10, 2013)Martyl Langsd ...

designed the 1947 cover of the publication which debuted the

Doomsday Clock The Doomsday Clock is a symbol that represents the likelihood of a man-made global catastrophe, in the opinion of the members of the ''Bulletin of the Atomic Scientists''. Maintained since 1947, the clock is a metaphor for threats to humanity ...

. Langsdorf also invented the diffusion cloud chamber and the reactor oscillator. Langsdorf died in

Elmhurst, Illinois Elmhurst is a city mostly in DuPage County and overlapping into Cook County in the U.S. state of Illinois, and a western suburb of Chicago. As of 2021, the city has an estimated population of 47,260. History Members of the Potawatomi Nativ ...

, from complications from

hip surgery Hip replacement is a surgical procedure in which the hip joint is replaced by a prosthetic implant, that is, a hip prosthesis. Hip replacement surgery can be performed as a total replacement or a hemi (half) replacement. Such joint replacement ...

.Staff report (May 25, 1996). Alexander Langsdorf Jr.; Physicist Involved with First Atomic Bomb. ''

St Louis Post-Dispatch The ''St. Louis Post-Dispatch'' is a major regional newspaper based in St. Louis, Missouri, serving the St. Louis metropolitan area. It is the largest daily newspaper in the metropolitan area by circulation, surpassing the ''Belleville News-Dem ...

References

External links

1965 Audio Interview with Alexander Langsdorf Jr. by Stephane Groueff
Voices of the Manhattan Project
Alexander Langsdorf Jr. Papers
via

{{DEFAULTSORT:Langsdorf, Alexander Jr. 1912 births 1996 deaths Scientists from Missouri Scientists from St. Louis Washington University physicists Physicists from Missouri Manhattan Project people Fellows of the American Physical Society Washington University in St. Louis alumni Massachusetts Institute of Technology alumni University of California, Berkeley fellows Washington University in St. Louis faculty