Editing Seth Neddermeyer

{{Short description|American physicist (1907–1988)}}
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{{Infobox scientist
|birth_name        = Seth Henry Neddermeyer
|image             = Neddermeyer-seth h.jpg
|caption           = Neddermeyer's ID badge photo from [[Los Alamos National Laboratory|Los Alamos]]
|birth_date        = {{Birth date|1907|9|16|mf=yes}}
|birth_place       = [[Richmond, Michigan]], United States
|death_date        = {{Death date and age|1988|01|29|1907|09|16|mf=yes}}
|death_place       = [[Seattle, Washington]], United States
|field             = [[Physics]]
|work_institution  = {{Unbulleted list
| [[National Bureau of Standards]]
| [[Los Alamos Laboratory]]
| [[University of Washington]]
}}
|education         = [[University of Olivet]]<br>[[Stanford University]] ([[Bachelor of Arts|AB]])<br>[[California Institute of Technology]] ([[Master of Science|MS]], [[Doctor of Philosophy|PhD]])
|doctoral_advisor  = [[Carl D. Anderson]]
|doctoral_students =
|thesis_title      = The absorption of high energy electrons
|thesis_url        = https://www.proquest.com/docview/301831835/
|thesis_year       = 1935
 |known_for         = {{Unbulleted list
| Co-discoverer of the [[muon]]
| Implosion-type [[atomic bomb]]
}}
|prizes            = [[Enrico Fermi award]] (1982)
|religion          =
|footnotes         =
|spouse            =
}}
'''Seth Henry Neddermeyer''' (September 16, 1907&nbsp;– January 29, 1988) was an American physicist who co-discovered the [[muon]], and later championed the [[implosion-type nuclear weapon]] while working on the [[Manhattan Project]] at the [[Los Alamos Laboratory]] during [[World War II]].

==Early life==
Seth Henry Neddermeyer was born in [[Richmond, Michigan]], on September 16, 1907.<ref name="Physics Today">{{cite journal|last1=Geballe|first1=Ronald|last2=Lord|first2=Jere J.|last3=Streib|first3=John F.|title=Seth N. Neddermeyer|journal=Physics Today|date=November 1988|volume=41|issue=11|pages=109|doi=10.1063/1.2811634|bibcode=1988PhT....41k.109G|df=mdy-all|doi-access=free}}</ref> He attended [[Olivet College]], a small college that his mother, older sister, and uncle had also attended,<ref name="Oral">{{cite web |url=http://oralhistories.library.caltech.edu/199/1/Neddermeyer_OHO.pdf |title=Interview with Seth H. Neddermeyer |publisher=Caltech |date=May 7, 1984 |access-date=December 30, 2015 }}</ref> for two years before his family moved to California. He transferred to [[Stanford University]], from which received his [[Bachelor of Arts]] (AB) degree in 1929.<ref name="Physics Today" /> His interest in physics was inspired by the work of [[Robert A. Millikan]], and he enrolled in graduate school at [[California Institute of Technology]] (Caltech),<ref name="Oral"/> where he wrote his 1935 [[PhD]] thesis on "The absorption of high energy electrons",<ref name="Nobel">{{cite web |url=https://caltech.tind.io/record/581809 |title=The absorption of high energy electrons |publisher=[[Caltech]] |access-date=December 30, 2015 |archive-date=March 4, 2016 |archive-url=https://web.archive.org/web/20160304124604/https://caltech.tind.io/record/581809 |url-status=dead }}</ref><ref name="thesis-neddermeyer-1935">{{cite thesis |url=https://www.proquest.com/docview/301831835/ |title=The absorption of high energy electrons |date=1935 |publisher=[[California Institute of Technology]] |type=PhD |last=Neddermeyer |first=Seth H. |via=[[ProQuest]] |url-access=subscription |oclc=437064667}}</ref> under the supervision of [[Carl D. Anderson]]. He confirmed the theory espoused by [[Niels Bohr]] for this process. He also noted large radiative energy losses of electrons in [[lead]], in agreement with the theory propounded by [[Hans Bethe]] and [[Walter Heitler]].<ref name="Physics Today" />

Neddermeyer contributed to the research which led to the 1932 discovery of the [[positron]],<ref name="Physics Today" /> for which Anderson was awarded the [[Nobel Prize in Physics]] in 1936.<ref>{{cite web |url=https://www.nobelprize.org/nobel_prizes/physics/laureates/1936/anderson-bio.html |title=Carl D. Anderson - Biographical |publisher=The Nobel Foundation |access-date=December 30, 2015 }}</ref> That year, Neddermeyer and Anderson discovered the [[muon]], using [[cloud chamber]] measurements of [[cosmic rays]]. Their discovery predated [[Hideki Yukawa]]'s 1935 theory of [[meson]]s that postulated the particle as mediating the nuclear force. Anderson and Neddermeyer collaborated with Millikan in high altitude studies of cosmic rays, which confirmed [[Robert Oppenheimer]]'s theory that the [[Air shower (physics)|air showers]] produced in the atmosphere by cosmic rays contained electrons.<ref name="Physics Today" /> They also obtained the first evidence that [[gamma rays]] can generate positrons.<ref name="Nobel" />

==Manhattan Project work==
[[File:Implosion bomb animated.gif|thumb|right|Implosion mechanism]]
In early 1941, with [[World War II]] raging in Europe but the United States not yet a belligerent, Neddermeyer joined a team led by [[Charles C. Lauritsen]] and [[William A. Fowler]] at the Department of Terrestrial Magnetism at the [[Carnegie Institution of Washington]], and  then at the [[National Bureau of Standards]] in Washington, D.C., that worked on the photoelectric [[proximity fuze]].<ref name="Physics Today" /><ref name="Oral"/> After this work was completed, Neddermeyer was recruited by Oppenheimer to work at the [[Manhattan Project]]'s [[Los Alamos Laboratory]].<ref name="Physics Today" /> Neddermeyer was an early advocate for the development of an [[Implosion-type nuclear weapon|implosion technique]] for assembling a [[critical mass]] in an atomic bomb.<ref name="Critchfield">{{cite web |url=http://conservancy.umn.edu/bitstream/handle/11299/107233/oh134cc.pdf |title=Oral History Interview with Charles Critchfield |access-date=December 30, 2015 }}</ref> Although implosion was suggested by [[Richard Tolman]] as early as 1942 and discussed in the introductory lectures given to Los Alamos scientists by [[Robert Serber]], Neddermeyer was one of the first to urge its full development.<ref name="Critchfield" />{{sfn|Serber|1942|p=59}} Unable to find much initial enthusiasm for the concept among his fellow Los Alamos scientists, Neddermeyer presented the first substantial technical analysis of implosion in late April 1943. Oppenheimer considered this to be the beginning of implosion research at Los Alamos.{{sfn|Hoddeson|Henriksen|Meade|Westfall|1993|pp=55–56}}

Though many remained unimpressed, Oppenheimer appointed Neddermeyer the head of a new group to test implosion.{{sfn|Rhodes|1986|pp=466-67}} His group became the E-5 (Implosion) Group, which was part of [[Captain (United States O-6)|Captain]] [[William S. Parsons]]' E Division.{{sfn|Hoddeson|Henriksen|Meade|Westfall|1993|pp=86–90}} A [[gun-type nuclear weapon]] was the preferred method, but implosion research constituted a backup.{{sfn|Hoddeson|Henriksen|Meade|Westfall|1993|p = 67}} Neddermeyer embarked on an intensive series of experiments testing cylindrical implosions. The result was a series of distorted shapes.{{sfn|Hoddeson|Henriksen|Meade|Westfall|1993|pp=86–90}} Progress was made; Neddermeyer and a member of his team, [[Hugh Bradner]], along with [[James L. Tuck]] from the [[British contribution to the Manhattan Project|British Mission]], conceived the idea of [[explosive lens]]es, in which shaped charges are used to focus the force of an explosion.<ref name="Critchfield" /> Nevertheless, seemingly unsolvable problems with [[shock wave]] uniformity brought progress on implosion to a crawl.{{sfn|Hoddeson|Henriksen|Meade|Westfall|1993|pp=86–90}}

By September 1943, Neddermeyer's team had grown from five people to fifty. That month, [[John von Neumann]] came to Los Alamos at Oppenheimer's request. Von Neumann was impressed by the implosion concept and, working with [[Edward Teller]], an old friend, made a series of suggestions. Von Neumann was able to create a sound mathematical model of implosion, enabling Neddermeyer to present a proposal for a greatly expanded research program. [[Edwin McMillan]] and [[Isidor Isaac Rabi]] recommended that [[George Kistiakowsky]], who had a specialized knowledge in the precision use of explosives, be brought in to help the program.{{sfn|Rhodes|1986|pp=541-43}}{{sfn|Hoddeson|Henriksen|Meade|Westfall|1993|pp =129-135}} In February 1944, Kistiakowsky became Parsons' deputy for implosion.{{sfn|Hoddeson|Henriksen|Meade|Westfall|1993|p =139}}

In April 1944, tests on the first sample of [[plutonium]] that had been produced with neutrons in a nuclear reactor revealed that reactor-bred plutonium contained five times more [[plutonium-240]] than that hitherto produced in [[cyclotron]]s. This unwanted isotope that spontaneously decayed and produced neutrons promised to cause a [[predetonation]] without sufficiently quick critical mass assembly. It now became apparent that only implosion would work for practical plutonium bombs; a powerful enough gun could not be constructed small enough to be carried in an aircraft, and plutonium-240 was even more difficult to separate from plutonium-239 than the isotopes of uranium that were giving the rest of the Manhattan Project such difficulties. Plutonium was unusable unless implosion worked, but only plutonium could be produced in quantities that would allow regular production of atomic bombs. Thus, the implosion technique now suddenly stood as the key to production of nuclear weapons.{{sfn|Hoddeson|Henriksen|Meade|Westfall|1993|pp=240-247}}

In mid-June 1944, a report from Kistiakowsky to Oppenheimer detailing dysfunctionality within the implosion team led to the ousting of Neddermeyer.{{sfn|Rhodes|1986|p=547}} He was replaced as the head of the E-5 Group by Kistiakowsky on June 15, 1944, but remained a technical adviser to the implosion program, with group leader status.{{sfn|Hoddeson|Henriksen|Meade|Westfall|1993|p=175}} Neddermeyer was said to have been much embittered by this episode.{{sfn|Rhodes|1986|p=547}} In Oppenheimer's August 1944 reorganization of the Los Alamos Laboratory, Neddermeyer's group was renamed X-1, with [[Norris Bradbury]] as group leader.{{sfn|Hoddeson|Henriksen|Meade|Westfall|1993|pp=240-247}} The implosion method championed by Neddermeyer was used in the first atom bomb exploded (in the [[Trinity test]]), the [[Fat Man]] bomb dropped on [[Nagasaki, Nagasaki|Nagasaki]], and almost all modern nuclear weapons.{{sfn|Hoddeson|Henriksen|Meade|Westfall|1993|pp=411-414}} Kistiakowsky later insisted that "the real invention should be given full credit to [Seth] Neddermeyer" (sic).<ref>{{cite web |url=http://manhattanprojectvoices.org/oral-histories/george-kistiakowskys-interview |title=George Kistiakowsky's Interview |work=[[Voices of the Manhattan Project]]|access-date=December 30, 2015 }}</ref>

==Later years==
In 1946, after World War II ended, Neddermeyer left Los Alamos to become an [[associate professor]] at the  [[University of Washington]], where he would spend the rest of his career. In due course he became a full professor.<ref name="acap">{{cite web |url=https://www.aip.org/history/acap/biographies/bio.jsp?neddermeyers |title=Seth Neddermeyer |publisher=Array of Contemporary American Physicists |access-date=December 30, 2015 |url-status=dead |archive-url=https://web.archive.org/web/20160201140900/https://www.aip.org/history/acap/biographies/bio.jsp?neddermeyers |archive-date=February 1, 2016 |df=mdy-all }}</ref> He resumed his studies of cosmic rays using a cloud chamber and a new device that he invented to measure the speed of charged particles known as a "chronotron". He was particularly interested in the properties of the muon, and conducted experiments with muons at [[SLAC]]. He participated in the [[DUMAND Project]], for which he helped design large-scale underwater [[neutrino]] detectors.<ref name="Physics Today"/> Neddermeyer became interested in [[parapsychology]], insisting, in spite of the skepticism of many colleagues, that it warranted proper scientific investigation.<ref name="Physics Today"/><ref name="Oral"/> He retired in 1973, becoming a [[professor emeritus]],<ref name="acap"/> but he continued his research activities for as long as his health permitted. He was afflicted with [[Parkinson's disease]].<ref name="obit"/>

In 1982, he was presented with the [[United States Department of Energy|Department of Energy]]'s [[Enrico Fermi award]]. His citation read:{{blockquote|For participating in the discovery of the positron, for his share in the discovery of the muon, the first of the subatomic particles; for his invention of the implosion technique for assembling nuclear explosives; and for his ingenuity, foresight, and perseverance in finding solutions for what at first seemed to be unsolvable engineering difficulties.<ref>{{cite web |title=Seth Neddermeyer, 1982 |publisher=-U.S. DOE Office of Science (SC) |url=http://science.energy.gov/fermi/award-laureates/1980s/neddermeyer/ |access-date=December 30, 2015 }}</ref> }}

In later life, Neddermeyer was sometimes troubled by the nuclear weapons he had helped to invent.<ref name="Physics Today"/> He told an interviewer in 1983:{{blockquote|I get so overwhelmed by a feeling of terrible guilt when I think about the history of the bomb. I'm terribly worried now about the current world situation. What the hell can we do about it?<ref name="obit">{{cite news |newspaper=[[The Washington Post]] |date=February 2, 1988 |title=Seth Neddermeyer, 80, dies |url=https://www.washingtonpost.com/archive/local/1988/02/02/seth-neddermeyer-80-dies/95e11307-e574-487d-bebc-6e6bbc2dfb7e/ |access-date=December 30, 2015 }}</ref> }}

Neddermeyer died in [[Seattle]] on  January 29, 1988,<ref name="Physics Today" />  from complications of Parkinson's disease.<ref>{{cite news|title=A-bomb scientist dies at age 80|url=https://www.newspapers.com/clip/912541/abomb_scientist_dies_at_age_80/?|access-date=August 24, 2014|work=The San Bernardino County Sun|date=February 1, 1988|page=6|via=[[Newspapers.com]]}} {{Open access}}</ref>

==In popular culture==
Neddermeyer is portrayed by [[Colin Bennett (actor)|Colin Bennett]] in the 1980 BBC series ''[[Oppenheimer (TV series)|Oppenheimer]]'', by Joe D'Angerio in ''[[Fat Man and Little Boy (film)|Fat Man and Little Boy]]'', and by [[Devon Bostick]] in the [[Christopher Nolan]]-directed film ''[[Oppenheimer (film)|Oppenheimer]]'' (2023).<ref>{{Cite web |last=Grobar |first=Matt |date=March 16, 2022 |title=Devon Bostick Joins Universal's ''Oppenheimer''; Sony's George Foreman Biopic Adds Deion Smith |url=https://deadline.com/2022/03/devon-bostick-joins-oppenheimer-sonys-george-foreman-biopic-adds-deion-smith-1234980250/ |access-date=March 16, 2022 |website=[[Deadline Hollywood]]}}</ref>

==Notes==
{{reflist|30em}}

==References==
*{{cite book |last1=Hoddeson |first1=Lillian|authorlink=Lillian Hoddeson |first2=Paul W. |last2=Henriksen |first3=Roger A. |last3=Meade |first4=Catherine L. |last4=Westfall |author4-link= Catherine Westfall |title=Critical Assembly: A Technical History of Los Alamos During the Oppenheimer Years, 1943–1945 |location=New York |publisher=Cambridge University Press |year=1993 |isbn=0-521-44132-3 |oclc=26764320 |url-access=registration |url=https://archive.org/details/criticalassembly0000unse }}
*{{cite book |last=Rhodes |first=Richard |authorlink=Richard Rhodes |title=The Making of the Atomic Bomb |year=1986 |publisher=Simon & Schuster |location=London |isbn=0-671-44133-7|title-link=The Making of the Atomic Bomb }}
* {{cite book |last=Serber |first=Robert |authorlink=Robert Serber |title=The Los Alamos Primer: The First Lectures on How to Build an Atomic Bomb |publisher=University of California Press |year=1942 |isbn=0-520-07576-5 }}

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{{DEFAULTSORT:Neddermeyer, Seth}}
[[Category:1907 births]]
[[Category:1988 deaths]]
[[Category:20th-century American physicists]]
[[Category:Manhattan Project people]]
[[Category:Stanford University alumni]]
[[Category:California Institute of Technology alumni]]
[[Category:University of Washington faculty]]
[[Category:Enrico Fermi Award recipients]]
[[Category:Neurological disease deaths in Washington (state)]]
[[Category:Deaths from Parkinson's disease in the United States]]
[[Category:People from Richmond, Michigan]]
[[Category:Fellows of the American Physical Society]]
[[Category:Nuclear weapons scientists and engineers]]