Charles Critchfield | |
|---|---|
 Critchfield'sLos Alamos ID badge photo | |
| Born | June 7, 1910 Shreve, Ohio, US |
| Died | February 12, 1994 (aged 83) |
| Education | George Washington University(BS,MS,PhD) |
| Known for | Nuclear weapons Manhattan Project Balloon technology |
| Scientific career | |
| Fields | Mathematical Physics |
| Institutions | Institute for Advanced Study Harvard University Carnegie Institution Los Alamos National Laboratory University of Minnesota |
| Doctoral advisor | Edward Teller |
Charles Louis Critchfield (June 7, 1910 – February 12, 1994) was an Americanmathematical physicist. A graduate ofGeorge Washington University, where he earned his PhD in physics under the direction ofEdward Teller in 1939, he conducted research inballistics at theInstitute for Advanced Study inPrinceton and theBallistic Research Laboratory at theAberdeen Proving Ground, and received three patents for improvedsabot designs.
In 1943, Teller andRobert Oppenheimer persuaded Critchfield to come to theManhattan Project'sLos Alamos National Laboratory, where he joined the Ordnance Division underCaptainWilliam Parsons on thegun-type fission weapons,Little Boy andThin Man. After it was discovered that the Thin Man design would not work, he was transferred toRobert Bacher's Gadget Division as the leader of the Initiator group, which was responsible for the design and testing of the"Urchin" neutron initiator that provided the burst of neutrons that kick-started the nuclear detonation of theFat Man weapon.
After the war he became a professor at theUniversity of Minnesota, and then vice president for research at theConvair division ofGeneral Dynamics, where he worked on theAtlas family of rockets. In 1961,J. Carson Mark andNorris Bradbury offered him a position at Los Alamos, which he held until he retired in 1977.
Charles Louis Critchfield was born inShreve, Ohio, on June 7, 1910, and grew up in Washington, D.C.[1][2] He received hisB.S. (1934) andM.A. (1936) degrees in mathematics fromGeorge Washington University, where he also earned aPhD in Physics (1939) under the direction ofEdward Teller.[3]
During Critchfield's graduate studies, Teller's colleagueGeorge Gamow[4] introduced him toHans Bethe, with whom he wrote a paper in 1938, which analyzed thenuclear fusion ofprotons intodeuterons.[5] The next year, Bethe showed that this process is a key link in theproton-proton chain reaction and theCNO cycle, which are the major ways that nuclear energy is released in thesolar core and in massive stars.[6] In 1967, Bethe was awarded theNobel Prize for this work onstellar nucleosynthesis.[7]
After he graduated, Critchfield taught optics for a year at theUniversity of Rochester at the invitation ofVictor Weisskopf.[3] In 1940, he was awarded aNational Research Council fellowship, and went to work underEugene Wigner at theInstitute for Advanced Study inPrinceton.[8] At this time, Robert Kent had just recruitedJohn von Neumann to the advisory board of theBallistic Research Laboratory at theAberdeen Proving Ground. Critchfield joined von Neumann and Wigner there on several visits.[9][10]
In 1942, after a brief stay atHarvard University, Critchfield went to theCarnegie Institution of Washington, where he continued his ballistic studies, which resulted in three patents for improvedsabot designs.[11] Because of his experience withballistics, Teller andRobert Oppenheimer persuaded Critchfield to come to theManhattan Project'sLos Alamos National Laboratory in 1943,[12] where he joined the Ordnance Division underCaptainWilliam Parsons.[10] As leader of the target, projectile, and source group, he worked on thegun-type fission weapons,Little Boy andThin Man.[13]
In April 1944, the Manhattan Project experienced a crisis whenEmilio Segrè discovered thatplutonium made innuclear reactors would not work in Thin Man.[13] In response, Oppenheimer completely reorganized the laboratory to focus on development of animplosion-type nuclear weapon in August. He reassigned Critchfield to a new Gadget Division underRobert Bacher, as the leader of the Initiator group.[14] This group was responsible for the design and testing of the"Urchin" neutron initiator, which provided a burst of neutrons that kick-started the nuclear detonation of theFat Man weapon.[15]
Critchfield left Los Alamos in 1946 and returned to George Washington University, but soon left to join Wigner at theOak Ridge National Laboratory.[3][16] In 1947 he became an assistant professor at theUniversity of Minnesota, where he participated, withEdward P. Ney andJohn R. Winckler, in a classified project to improve balloon technology.[17] Here, with Leland S. Bohl, he invented and patented the natural shape balloon,[18] and participated, with Ney and his student Sophie Oleksa, in an early search for primary cosmic ray electrons.[19]
In 1955, after advancing to full professor at Minnesota, Critchfield became vice president for research at theConvair division ofGeneral Dynamics.[20] Here, he worked on theAtlas family of rockets, which began as a series ofICBMs and evolved into launch vehicles forProject Mercury andmany other space missions. He also created the Convair Scientific Research Laboratory whose staff were expected to serve as consultants for the company's engineering divisions and to carry out basic scientific research. In 1957, Critchfield's student William C. Erickson joined the staff, and created the Clark Lake Radio Observatory.[21] In 1963, this facility, where observations focused on long wavelength radio waves, was transferred to theUniversity of Maryland, where Erickson had become a professor. Although the original observatory has been abandoned, similar research continues at the much largerLong Wavelength Array in centralNew Mexico.[22]
In early November 1959, PresidentDwight D. Eisenhower'sSecretary of DefenseNeil H. McElroy selected Critchfield to be head of theDefense Advanced Research Projects Agency. McElroy hoped that Critchfield would be able to fix the nation's troubled missile program, but Critchfield was reluctant to serve at the director's $19,000 salary. McElroy then offered to let Critchfield serve without pay, with the government paying only his expenses of $15 per day, while allowing Critchfield to continue to draw his Convair salary of around $40,000. Critchfield accepted this offer, but ran into a storm of political and media criticism over the conflict of interest involved in heading an agency that did $4 million worth of business with Convair each year. Critchfield then withdrew his name from consideration.[23][24]
In 1961, Critchfield accepted a professorship at theUniversity of Wisconsin, but before he moved to Madison, his friends at Los Alamos,J. Carson Mark andNorris Bradbury offered him a position there that he took instead.[20] He held this position until he retired in 1977, but he continued his association with the laboratory until his death after a long battle with cancer on February 12, 1994. His obituary inPhysics Today was written by Carson Mark,Louis Rosen, Edward Teller, and Roger Meade.[3]
Charles Critchfield is buried next to his wife, Jean, in Guaje Pines Cemetery in Los Alamos County, New Mexico.[25]
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