Charles Critchfield Charles Louis Critchfield ( June 7 , 1910 – February 12 , 1994 ) was an American mathematical physicist . A graduate of George Washington University , where he earned his PhD in Physics under the direction of Edward Teller in 1939 , he conducted research in ballistics at the Institute for Advanced Study in Princeton and the Ballistic Research Laboratory at the Aberdeen Proving Ground , and received three patents for improved sabot designs . In 1943 , Teller and Robert Oppenheimer persuaded Critchfield to come to the Manhattan Project ' s Los Alamos National Laboratory , where he joined the Ordnance Division under Captain William Parsons on the gun - type fission weapon s , Little Boy and Thin Man . After it was discovered that the Thin Man design would not work , he was transferred to Robert 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 the Fat Man weapon . After the war he became a professor at the University of Minnesota , and then vice president for research at the Convair division of General Dynamics , where he worked on the Atlas family of rockets . In 1961 , J . Carson Mark and Norris Bradbury offered him a position at Los Alamos , which he held until he retired in 1977 . Early life . Charles Louis Critchfield was born in Shreve , Ohio , on June 7 , 1910 , and grew up in Washington , D . C . He received his B . S . ( 1934 ) and Master ( 1936 ) degrees in Mathematics from George Washington University , where he also earned a PhD in Physics ( 1939 ) under the direction of Edward Teller . During Critchfield ' s graduate studies , Teller ' s colleague George Gamow introduced him to Hans Bethe , with whom he wrote a paper in 1938 , which analyzed the nuclear fusion of protons into deuterons . The next year , Bethe showed that this process is a key link in the proton - proton chain reaction and the CNO cycle , which are the major ways that nuclear energy is released in the solar core and in massive stars . In 1967 , Bethe was awarded the Nobel Prize for this work on stellar nucleosynthesis . World War II . After he graduated , Critchfield taught optics for a year at the University of Rochester at the invitation of Victor Weisskopf . In 1940 , he was awarded a National Research Council fellowship , and went to work under Eugene Wigner at the Institute for Advanced Study in Princeton . At this time , Robert Kent had just recruited John von Neumann to the advisory board of the Ballistic Research Laboratory at the Aberdeen Proving Ground . Critchfield joined von Neumann and Wigner there on several visits . In 1942 , after a brief stay at Harvard University , Critchfield went to the Carnegie Institution of Washington , where he continued his ballistic studies , which resulted in three patents for improved sabot designs . Because of his experience with ballistics , Teller and Robert Oppenheimer persuaded Critchfield to come to the Manhattan Project ' s Los Alamos National Laboratory in 1943 , where he joined the Ordnance Division under Captain William Parsons . As leader of the target , projectile , and source group , he worked on the gun - type fission weapon s , Little Boy and Thin Man . In April 1944 , the Manhattan Project experienced a crisis when Emilio Segrè discovered that plutonium made in nuclear reactors would not work in Thin Man . In response , Oppenheimer completely reorganized the laboratory to focus on development of an implosion - type nuclear weapon in August . He reassigned Critchfield to a new Gadget Division under Robert Bacher , as the leader of the Initiator group . 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 the Fat Man weapon . Postwar . Critchfield left Los Alamos in 1946 and returned to George Washington University , but soon left to join Wigner at the Oak Ridge National Laboratory . In 1947 he became an assistant professor at the University of Minnesota , where he participated , with Edward P . Ney and John R . Winckler , in a classified project to improve balloon technology . Here , with Leland S . Bohl , he invented and patented the natural shape balloon , and participated , with Ney and his student Sophie Oleksa , in an early search for primary cosmic ray electrons . In 1955 , after advancing to full professor at Minnesota , Critchfield became vice president for research at the Convair division of General Dynamics . Here , he worked on the Atlas family of rockets , which began as a series of ICBMs and evolved into launch vehicles for Project Mercury and many 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 . In 1963 , this facility , where observations focused on long wavelength radio waves , was transferred to the University of Maryland , where Erickson had become a professor . Although the original observatory has been abandoned , similar research continues at the much larger Long Wavelength Array in central New Mexico . Later life . In early November 1959 , President Dwight D . Eisenhower ' s Secretary of Defense Neil H . McElroy selected Critchfield to be head of the Defense Advanced Research Projects Agency . McElroy hoped that Critchfield would be able to fix the nation ' s trouble 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 . In 1961 , Critchfield accepted a professorship at the University of Wisconsin , but before he moved to Madison , his friends at Los Alamos , J . Carson Mark and Norris Bradbury offered him a position there that he took instead . 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 in Physics Today was written by Carson Mark , Louis Rosen , Edward Teller , and Roger Meade . Charles Critchfield is buried next to his wife , Jean , in Guaje Pines Cemetery in Los Alamos County , New Mexico .