Seth Neddermeyer

Seth Henry Neddermeyer (16 September 1907, Richmond, Michigan - 29 January 1988, Seattle, Washington) was an American physicist who worked in the Manhattan Project. He had been Carl D. Anderson's student at Caltech. In 1937, he helped discover muons using cloud chamber measurements of cosmic rays.

Manhattan Project work

While at Los Alamos, Neddermeyer was an early advocate for development of an implosion technique for assembling a critical mass in an atomic bomb. While implosion was previously suggested by Richard Tolman as early as 1942, [Serber, Robert, The Los Alamos Primer: The First Lectures on How to Build an Atomic Bomb, pg 59, (University of California Press, 1992) ISBN 0-520-07576-5] 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. Unable to find much initial enthusiasm for the concept amongst his fellow Los Alamos scientists, Neddermeyer presented the first substantial technical analysis of implosion in late April 1943. Though many remained unimpressed, Robert Oppenheimer appointed Neddermeyer the head of a new group to test implosion. [Rhodes, Richard, The Making of the Atomic Bomb, Simon and Schuster, 1986, p. 466-67.] Neddermeyer embarked on an intensive series of experiments testing cylindrical implosions.

Nevertheless, seemingly irresolvable problems with shockwave uniformity brought progress on implosion to a crawl. At the urging of James Conant, Oppenheimer, brought in George Kistiakowsky (who had a specialized knowledge in the precision use of explosives) to help jumpstart flagging program in January 1944. [Rhodes, Richard, The Making of the Atomic Bomb, Simon and Schuster, 1986, p. 541-43.] In mid-June 1944 Kistiakowsky’s report to Oppenheimer about the dysfunctionality within the implosion team led to the ouster of Neddermeyer and his replacement by Kistiakowsky. [Rhodes, Richard, The Making of the Atomic Bomb, Simon and Schuster, 1986, p. 547.] Neddermeyer was said to have been much embittered by this event.

Accordingly, it was left to others like Kistiakowsky (who contributed a background in military ordnance and explosives), Robert Christy (who contributed the insight that a subcritical sphere of plutonium could be imploded to a critical mass), John von Neumann (who contributed the breakthrough mathematical model for using shaped charges to create a truly spherical implosion), and Edward Teller (whose knowledge of the compressibility of metals lead to the use of density change to achieve criticality rather than mere, same-density, “assembly” [Serber, Robert, The Los Alamos Primer: The First Lectures on How to Build an Atomic Bomb, pg xvi, (University of California Press, 1992) ISBN 0-520-07576-5] ), to complete the work. The implosion method championed by Neddermeyer was used in the first atom bomb exploded (Trinity test), the Fat Man bomb dropped on Nagasaki, and almost all modern weapons.

In 1982, he was awarded with the Enrico Fermi award.

Notes

External links

* [http://nobelprize.org/physics/laureates/1936/anderson-bio.html Carl D. Anderson Biography]
* [http://www.sc.doe.gov/fermi/html/Laureates/1980s/sethn.htm Neddermeyer's Enrico Fermi award]
* [http://alsos.wlu.edu/qsearch.aspx?browse=people/Neddermeyer,+Seth Entry for Seth Neddermeyer in the Alsos Digital Library for Nuclear Issues]