Kenneth Bainbridge | |
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| Born | Kenneth Tompkins Bainbridge (1904-07-27)July 27, 1904 Cooperstown, New York, U.S. |
| Died | July 14, 1996(1996-07-14) (aged 91) Lexington, Massachusetts, U.S. |
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| Scientific career | |
| Fields | Physics |
| Institutions | Harvard University |
| Doctoral advisor | Henry DeWolf Smyth |
| Doctoral students | Edward Mills Purcell |
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Kenneth Tompkins Bainbridge (July 27, 1904 – July 14, 1996) was an American physicist atHarvard University who worked oncyclotron research. His accurate measurements of mass differences between nuclear isotopes allowed him to confirmAlbert Einstein'smass–energy equivalence concept.[1] He was the Director of theManhattan Project'sTrinity nuclear test, which took place July 16, 1945. Bainbridge described the Trinity explosion as a "foul and awesome display".[2] He remarked toJ. Robert Oppenheimer immediately after the test, "Now we are all sons of bitches."[2] This marked the beginning of his dedication to ending the testing of nuclear weapons and to efforts to maintain civilian control of future developments in that field.
Kenneth Tompkins Bainbridge was born inCooperstown, New York, on July 27, 1904.[3] He had one older brother and one younger brother.[4] He was educated atHorace Mann School in New York. While at high school he developed an interest inham radio which inspired him to enterMassachusetts Institute of Technology (MIT) in 1921 to studyelectrical engineering. In five years he earned bothBachelor of Science (S.B.) andMaster of Science (S.M.) degrees. During the summer breaks he worked atGeneral Electric's laboratories inLynn, Massachusetts andSchenectady, New York. While there he obtained three patents related tophotoelectric tubes.[3][5][6][7]
Bainbridge's work at General Electric made him aware of how interested he was inphysics. Upon graduating from MIT in 1926, he enrolled atPrinceton University, whereKarl T. Compton, a consultant to General Electric, was on the faculty.[8] While at Princeton, Bainbridge created his firstmass spectrograph, came up with methods for identifying elements, and started studyingnuclei.[4] In 1929, he was awarded a Ph.D. in his new field, writing his thesis on "A search forelement 87 by analysis of positive rays" under the supervision ofHenry DeWolf Smyth.[9]
Bainbridge enjoyed a series of prestigious fellowships after graduation. He was awarded aNational Research Council, and then aBartol Research Foundation fellowship. At the time theFranklin Institute's Bartol Research Foundation was located on theSwarthmore College campus in Pennsylvania, and was directed byW. F. G. Swann, an English physicist with an interest innuclear physics.[10] Bainbridge spent four years (1929-1933) at the Franklin Institute’s Bartol laboratories and during his time there Bainbridge learned how to take subtle and difficult mass measurements.[4] Bainbridge married Margaret ("Peg") Pitkin, a member of the Swarthmore teaching faculty, in September 1931.[10] They had a son, Martin Keeler, and two daughters, Joan and Margaret Tomkins.[11][12]
In 1932, Bainbridge developed amass spectrometer with a resolving power of 600 and a relative precision of one part in 10,000.[13] He used this instrument to verifyAlbert Einstein'smass–energy equivalence, E = mc2.[14] Since Bainbridge was the first to successfully test Einstein’s theory of the equivalence of mass and energy, he was awarded the Louis Edward Levy Medal.[4]Francis William Aston wrote that:
By establishing accurate comparisons of the masses of the light particles concerned in nuclear disintegrations, particularly that of7Li, discovered by Cockcroft and Walton, he achieved a noteworthy triumph in the experimental proof of the fundamental theory of Einstein of the equivalence of mass and energy.[15]
In 1933, Bainbridge was awarded a prestigiousGuggenheim Fellowship, which he used to travel to England and work atErnest Rutherford'sCavendish Laboratory atCambridge University. While there he continued his work developing the mass spectrograph, and became friends with the British physicistJohn Cockcroft.[10] Also, during Bainbridge’s time in Cambridge, he produced very advanced mass spectrographs and ended up becoming a leading expert in the field of mass spectroscopy. It was at Cambridge when Bainbridge first began to work withnuclear chain reactions.[4]
When his Guggenheim fellowship expired in September 1934, he returned to the United States, where he accepted an associate professorship atHarvard University. He started by building a new mass spectrograph that he had designed with at the Cavendish Laboratory. Working withJ. Curry Street, he commenced work on acyclotron.[10] They had a design for a 37-inch (940 mm) cyclotron provided byErnest Lawrence, but decided to build a 42-inch (1,100 mm) cyclotron instead.[16]
Bainbridge was elected a Fellow of theAmerican Academy of Arts and Sciences in 1937.[17] His interest in mass spectroscopy led naturally to an interest in the relative abundance ofisotopes. The discovery ofnuclear fission inuranium-235 led to an interest in separating this isotope. He proposed using aHolweck pump to produce the vacuum necessary for this work, and enlistedGeorge B. Kistiakowsky andE. Bright Wilson to help. There was little interest in their work because research was being carried out elsewhere.[18] Bainbridge ended up bringing his Holweck pump to government authorities in Washington D.C., however the government authorities claimed that scientists working for the government were already working on a process of isotope separation and that he should discontinue his work using the Holweck pump forisotope separation.[4] In 1943, their cyclotron was requisitioned byEdwin McMillan for use by the U. S. Army. It was packed up and carted off toLos Alamos, New Mexico.[10][16]
In September 1940, withWorld War II raging in Europe, the BritishTizard Mission brought a number of new technologies to the United States, including acavity magnetron, a high-powered device that generatesmicrowaves using the interaction of a stream ofelectrons with amagnetic field. This device, which promised to revolutionizeradar, demolished any thoughts the Americans had entertained about their technological leadership.Alfred Lee Loomis of theNational Defense Research Committee established theRadiation Laboratory at theMassachusetts Institute of Technology (MIT) to develop this radar technology.[19] In October, Bainbridge became one of the first scientists to be recruited for the Radiation Laboratory by Ernest Lawrence.[20]
Bainbridge spent two and a half years at MIT’s Radiation laboratory working on radar development.[4] The scientists divided up the work between them; Bainbridge drewpulse modulators.[21] Working with the Navy, he helped develop high-powered radars for warships.[11] Then, from March 1941 to May 1941, Bainbridge was sent to England to discuss radar development with the English. While he was in England, he was able to see firsthand the various radar equipment that the British had installed being used in combat. Bainbridge also met with British scientists and learned about the British’s efforts in developing an atomic bomb. When Bainbridge returned to the United States, he reported about the British's plans to build an atomic bomb. Bainbridge then continued to work on the development of radar technology at MIT.
Bainbridge eventually became the lead of a division of the lab that was responsible for ship-borne interception control radar, ground systems search and warning class radar, ground-based fire control radar, microwave early warning radar, search and fighter control radar, and fire control radar. Many of these radar technologies would find their way ontoaircraft carriers fighting the Japanese in the Pacific as the war went on.[4]
In May 1943, Bainbridge joinedRobert Oppenheimer's Project Y at Los Alamos.[16] He initially led E-2, the instrumentation group, which developed X-ray instrumentation for examining explosions.[22] In March 1944, he became head of a new group, E-9, which was charged with conducting the first nuclear test. In Oppenheimer's sweeping reorganization of the Los Alamos laboratory in August 1944, the E-9 Group became X-2.[23] He also worked on developing designs for the uraniumLittle Boy design dropped onHiroshima and the plutoniumFat Man design used onNagasaki. Additionally, Bainbridge also helped in the development of methods to determine the trajectories of the atomic bombs.[4]
In March 1945, Bainbridge was given the position of director of the Trinity Test.[4] Bainbridge was tasked with finding a site that was flat in order to be able to take accurate measurements of the explosion. The site also had to be unnoticeable for security reasons, but decently close toLos Alamos.[24] Bainbridge ended up finding a site that was approximately 200 miles away from Los Alamos, located in the Alamogordo Gunnery Range. Bainbridge along with his assistant director, John Williams who was also a physicist planned and oversaw the construction of the needed facilities at the test site. The facilities consisted of observation bunkers, hundreds of miles of wiring, miles of paved roads, as well as housing.[25] Additionally, Bainbridge played a role in the development of bomb detonator equipment and setting up equipment for measuring the yield of the explosion.[4] On July 16, 1945, Bainbridge and his colleagues conducted theTrinity nuclear test.[2] To his relief, the explosion of the firstatomic bomb went off without such drama, in what he later described as "a foul and awesome display".[2][26][27] He turned to Oppenheimer and said, "Now we are all sons of bitches."[2] After the conclusion of the Trinity test Bainbridge co-wrote the official account of the Trinity test that was given to the United States government.[4]
Bainbridge was relieved that the Trinity test had been a success, relating in a 1975Bulletin of the Atomic Scientists article, "I had a feeling of exhilaration that the 'gadget' had gone off properly followed by one of deep relief. I wouldn't have to go to the tower to see what had gone wrong."[2]
For his work on theManhattan Project, Bainbridge received two letters of commendation from the project's director,Major GeneralLeslie R. Groves, Jr. He also received aPresidential Certificate of Merit for his work at the MIT Radiation Laboratory.[28]
Bainbridge returned to Harvard after the war, and initiated the construction of a 96-inch (2,400 mm) synchro-cyclotron, which has since been dismantled.[29] Also, upon arriving back at Harvard, Bainbridge created a larger mass spectrograph. Utilizing his new device, Bainbridge was able to establish the existence of theneutrino, which is a basic component ofmatter that had eluded scientists for some time.[4] From 1950 to 1954, he chaired the physics department at Harvard. During those years, he drew the ire of SenatorJoseph McCarthy for his aggressive defense of his colleagues in academia. As chairman, he was responsible for the renovation of the old Jefferson Physical Laboratory, and he established the Morris Loeb Lectures in Physics. He also devoted a good deal of his time to improving the laboratory facilities for graduate students.[30] During Bainbridge’s remaining years at Harvard, he continued to work towards finding new mechanisms to obtain precise yields ofatomic masses.[4]
Throughout the 1950s, Bainbridge remained an outspoken proponent of civilian control ofnuclear power and the abandonment ofnuclear testing. In 1950 he was one of twelve prominent scientists who petitionedPresidentHarry S. Truman to declare that the United States would never be the first to use thehydrogen bomb.[11] Bainbridge retired from Harvard in 1975.[30]
Bainbridge's wife Margaret died suddenly in January 1967 from a blood clot in a broken wrist. He married Helen Brinkley King, an editor atWilliam Morrow in New York City, in October 1969.[31] She died in February 1989. A scholarship was established atSarah Lawrence College in her memory.[32] He died at his home inLexington, Massachusetts, on July 14, 1996. He was survived by his daughters from his first marriage, Joan Bainbridge Safford and Margaret Bainbridge Robinson.[11] He was buried in the Abel's Hill Cemetery onMartha's Vineyard, in a plot with his first wife Margaret and his son Martin.[31] His papers are in the Harvard University Archives.[33]
In the 2023 filmOppenheimer, he is portrayed byJosh Peck.[34]
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