- Arthur Jeffrey Dempster
Infobox_Scientist
name = Arthur Jeffrey Dempster
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birth_date = August 14, 1886
birth_place = Toronto, Canada
death_date = 1950
death_place = Stuart, Florida
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nationality = Canadian-American
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field = physicist
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alma_mater = B.S.University of Toronto
M.S.University of Toronto
Ph.D.University of Chicago
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known_for = Developed the first modern mass spectrometer, discovered 235U (used inatomic bomb s)
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footnotes =Arthur Jeffrey Dempster (
August 14 1886 -March 11 1950 ) was a Canadian-Americanphysicist best known for his work inmass spectrometry and his discovery of theuranium isotope 235U.Biography
Dempster was born in
Toronto ,Canada . He received his bachelor's andmaster's degree s at theUniversity of Toronto in 1909 and 1910, respectively. He travelled to study inGermany , and then left at the outset ofWorld War I for theUnited States ; there he received his Ph.D. in physics at theUniversity of Chicago . Dempster then joined thephysics faculty there in 1916, teaching and researching until his death in 1950, interrupted only duringWorld War II , when he worked on the secretManhattan Project to develop the world's firstnuclear weapon s. From 1943 to 1946, he was chief physicist of the University of Chicago'sMetallurgical Laboratory or "Met Lab" (this lab was integrally related to the Manhattan Project: it was founded to study the materials necessary for the manufacture of atomic bombs), and in 1946 took a position as a division director at theArgonne National Laboratory . Dempster died in 1950 inStuart, Florida .Research
In 1918, Dempster developed the first modern mass spectrometer, a scientific apparatus allowing physicists to identify compounds by the mass of elements in a sample, and determine the isotopic composition of elements in a sample. [ cite journal|title=A New Method of Positive Ray Analysis |journal=Phys. Rev.|date=April 1918|first=A. J.|last=Dempster|coauthors=|volume=11|issue=4|pages=316–325|doi= 10.1103/PhysRev.11.316|url=http://link.aps.org/abstract/PR/v11/p316|format=PDF|accessdate=2007-11-24 ] Dempster's mass spectrometer was over 100 times more accurate than previous versions, and established the basic theory and design of mass spectrometers that is still used to this day. Dempster's research over his career centered around the mass spectrometer and its applications, leading in 1935 to his discovery of the uranium isotope 235U. This isotope's ability to cause a rapidly expanding fission
nuclear chain reaction allowed the development of theatom bomb andnuclear power . Dempster was also well known as an authority onpositive ray s.References
* [http://libserv.aip.org:81/ipac20/ipac.jsp?uri=full=3100001~!542~!0&profile=icos "AIP International Catalog of Sources"] . Retrieved June 17, 2005.
*Armstrong, David; Burke, Monte; "et al." Forbes.com (December 23, 2002). [http://www.forbes.com/forbes/2002/1223/124_print.html "85 Innovations 1917-1938"] .
*Encyclopædia Britannica (2005). [http://www.britannica.com/eb/article?tocId=9029915 "Dempster, Arthur Jeffrey"] . Retrieved June 17, 2005.
* [http://www.todayinsci.com/8/8_14.htm "Today in Science History"] . Retrieved June 17, 2005.Persondata
NAME= Dempster, Arthur Jeffrey
ALTERNATIVE NAMES=
SHORT DESCRIPTION= Canadian-American physicist
DATE OF BIRTH= August 14, 1886
PLACE OF BIRTH= Toronto, Canada
DATE OF DEATH= 1950
PLACE OF DEATH= Stuart, Florida
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