Editing Ernest Lawrence (section)

=== Radiation Laboratory ===
After the outbreak of [[World War II]] in Europe, Lawrence became drawn into military projects. He helped recruit staff for the [[MIT Radiation Laboratory]], where American physicists developed the [[cavity magnetron]] invented by [[Mark Oliphant]]'s team in Britain. The name of the new laboratory was deliberately copied from Lawrence's laboratory in Berkeley for security reasons. He also became involved in recruiting staff for underwater sound laboratories to develop techniques for detecting German submarines. Meanwhile, work continued at Berkeley with cyclotrons. In December 1940, [[Glenn T. Seaborg]] and [[Emilio Segrè]] used the {{convert|60|in|cm|adj=on}} cyclotron to bombard [[uranium-238]] with [[deuterons]] producing a new element, [[neptunium-238]], which decayed by [[beta emission]] to form [[plutonium-238]]. One of its isotopes, [[plutonium-239]], could undergo nuclear fission, which provided another way to make an [[atomic bomb]].{{sfn|Alvarez|1970|p=274}}{{sfn|Childs|1968|pp=306–308}}<ref>{{Cite conference|title=The Plutonium Story |first=Glenn T. |last=Seaborg |conference=Actinides-1981 conference |location=Pacific Grove, California |date=September 10, 1981 |publisher=Lawrence Berkeley Laboratory, University of California |id=LBL-13492, DE82 004551 |osti=5808140}}</ref>

Lawrence offered Segrè a job as a research assistant—a relatively lowly position for someone who had discovered an element—for US$300 a month for six months. However, when Lawrence learned that Segrè was legally trapped in California, he reduced Segrè's salary further to US$116 a month.{{sfn|Segrè|1993|pp=147–148}} When the regents of the University of California wanted to terminate Segrè's employment owing to his foreign nationality, Lawrence managed to retain Segrè by hiring him as a part-time lecturer paid by the Rockefeller Foundation. Similar arrangements were made to retain his doctoral students [[Chien-Shiung Wu]] (a Chinese national) and [[Kenneth Ross MacKenzie]] (a Canadian national) when they graduated.{{sfn|Heilbron|Seidel|1989|pp=521–522}}

[[File:Diagram of uranium isotope separation in the calutron.png|thumb|right|Schematic diagram of uranium isotope separation in a [[calutron]]|alt=Another weird diagram. This one shows atoms being deflected by a magnet]]
In September 1941, Oliphant met with Lawrence and Oppenheimer at Berkeley, where they showed him the site for the new {{convert|184|in|m|adj=on}} cyclotron. Oliphant, in turn, took the Americans to task for not following up the recommendations of the British [[MAUD Committee]], which advocated a program to develop an [[atomic bomb]].{{sfn|Herken|2002|pp=38–41}} Lawrence had already thought about the problem of separating the fissile isotope [[uranium-235]] from [[uranium-238]], a process known today as [[uranium enrichment]]. Separating uranium isotopes was difficult because the two isotopes have very nearly identical chemical properties, and could only be separated gradually using their small mass differences. Separating isotopes with a [[mass spectrometer]] was a technique Oliphant had pioneered with [[lithium]] in 1934.<ref name="Electromagnetic separation">{{cite journal|first1=M. L. E. |last1=Oliphant |first2=E. S. |last2=Shire |first3=B. M. |last3=Crowther  |journal=Proceedings of the Royal Society A |title=Separation of the Isotopes of Lithium and Some Nuclear Transformations Observed with them |date=October 15, 1934 |volume=146 |issue=859 |pages=922–929 |doi=10.1098/rspa.1934.0197 |bibcode=1934RSPSA.146..922O |doi-access=free}}</ref>

Lawrence began converting his old 37-inch cyclotron into a giant mass spectrometer.{{sfn|Hewlett|Anderson|1962|pp=43–44}} On his recommendation, the director of the [[Manhattan Project]], [[Brigadier General (United States)|Brigadier General]] [[Leslie R. Groves Jr.]], appointed Oppenheimer as head of its [[Los Alamos Laboratory]] in [[New Mexico]]. While the Radiation laboratory developed the electromagnetic uranium enrichment process, the Los Alamos Laboratory designed and constructed the atomic bombs. Like the Radiation Laboratory, it was run by the University of California.{{sfn|Childs|1968|pp=337–339}}

Electromagnetic isotope separation used devices known as [[calutron]]s, a hybrid of two laboratory instruments, the mass spectrometer and cyclotron. The name was derived from "California university cyclotrons".{{sfn|Jones|1985|pp=117–119}} In November 1943, Lawrence's team at Berkeley was bolstered by 29 British scientists, including Oliphant.{{sfn|Childs|1968|p=347}}{{sfn|Jones|1985|p=124}}

In the electromagnetic process, a magnetic field deflected charged particles according to mass.{{sfn|Childs|1968|p=312}} The process was neither scientifically elegant nor industrially efficient.{{sfn|Fine|Remington|1972|p=684}} Compared with a [[gaseous diffusion]] plant or a [[nuclear reactor]], an electromagnetic separation plant would consume more scarce materials, require more manpower to operate, and cost more to build. Nonetheless, the process was approved because it was based on proven technology and therefore represented less risk. Moreover, it could be built in stages, and would rapidly reach industrial capacity.{{sfn|Jones|1985|pp=117–119}}