Edwin McMillan

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Edwin McMillan
Berkeley Radiation Laboratory
ThesisDeflection of a Beam of HCI Molecules in a Non-Homogeneous Electric Field (1933)
Doctoral advisorEdward Condon

Edwin Mattison McMillan (September 18, 1907 – September 7, 1991) was an American physicist credited with being the first to produce a

Glenn Seaborg
.

A graduate of

implosion-type nuclear weapon
.

McMillan co-invented the synchrotron with Vladimir Veksler, and after the war he returned to the Berkeley Radiation Laboratory to build them. He was appointed associate director of the Radiation Laboratory in 1954 and promoted to deputy director in 1958. He became director upon the death of lab founder Ernest Lawrence later that year, and remained director until his retirement in 1973.

Early life

McMillan was born in Redondo Beach, California, on September 18, 1907, the son of Edwin Harbaugh McMillan and his wife Anna Marie McMillan née Mattison.[1] He had a younger sister, Catherine Helen, whose son John Clauser (that is, McMillan's nephew) won the Nobel Prize in Physics in 2022.

McMillan's father was a physician, as was his father's twin brother, and three of his mother's brothers. On October 18, 1908, the family moved to Pasadena, California, where he attended McKinley Elementary School from 1913 to 1918, Grant School from 1918 to 1920, and then Pasadena High School, from which he graduated in 1924.[2]

California Institute of Technology (Caltech) was only a mile from his home, and he attended some public lectures there.[3] He entered Caltech in 1924. He did a research project with Linus Pauling as an undergraduate and received his Bachelor of Science degree in 1928 and his Master of Science degree in 1929,[1] writing an unpublished thesis on "An improved method for the determination of the radium content of rocks".[4] He then took his Doctor of Philosophy from Princeton University in 1933, writing his thesis on the "Deflection of a Beam of HCI Molecules in a Non-Homogeneous Electric Field" under the supervision of Edward Condon.[5][6]

Lawrence Berkeley Laboratory

McMillan (left) with Ernest Lawrence (right)

In 1932, McMillan was awarded a

Berkeley Radiation Laboratory, which Lawrence had founded the year before.[7] McMillan's initial work there involved attempting to measure the magnetic moment of the proton, but Otto Stern and Immanuel Estermann were able to carry out these measurements first.[2][8]

The main focus of the Radiation laboratory at this time was the development of the

hygroscopic calcium chloride. Radioactivity was found concentrated in it, proving that it was in the oxygen. This was followed by an investigation of the absorption of gamma rays produced by bombarding fluorine with protons.[8]

In 1935, McMillan, Lawrence and Robert Thornton carried out cyclotron experiments with deuteron beams that produced a series of unexpected results. Deuterons fused with a target

Robert Oppenheimer and his graduate student Melba Phillips developed the Oppenheimer–Phillips process to explain the phenomenon.[9] McMillan became an assistant professor in 1936, and an associate professor in 1941.[1] With Samuel Ruben, he also discovered the isotope beryllium-10 in 1940.[6] This was both interesting and difficult to isolate due to its extraordinarily long half-life, about 1.39 million years.[10]

Discovery of neptunium

Following the discovery of

uranium-239, which had been reported by Hahn and Strassmann. McMillan suspected that the other was an isotope of a new, undiscovered element, with an atomic number of 93.[11]

At the time it was believed that element 93 would have similar chemistry to rhenium, so he began working with Emilio Segrè, an expert on that element from his discovery of its homolog technetium. Both scientists began their work using the prevailing theory, but Segrè rapidly determined that McMillan's sample was not at all similar to rhenium. Instead, when he reacted it with hydrogen fluoride (HF) with a strong oxidizing agent present, it behaved like members of the rare-earth elements.[12] Since these comprise a large percentage of fission products, Segrè and McMillan decided that the half-life must have been simply another fission product, titling the article "An Unsuccessful Search for Transuranium Elements".[13]

McMillan realized that his 1939 work with Segrè had failed to test the chemical reactions of the radioactive source with sufficient rigor. In a new experiment, McMillan tried subjecting the unknown substance to HF in the presence of a

actinide series
. As a final step, McMillan and Abelson prepared a much larger sample of bombarded uranium that had a prominent 23-minute half-life from 239U and demonstrated conclusively that the unknown 2.3-day half-life increased in strength in concert with a decrease in the 23-minute activity through the following reaction:

This proved that the unknown radioactive source originated from the decay of uranium and, coupled with the previous observation that the source was different chemically from all known elements, proved beyond all doubt that a new element had been discovered. McMillan and Abelson published their results in an article entitled Radioactive Element 93 in the

Glenn Seaborg to pursue this line of research and discover the second transuranium element, plutonium. In 1951, McMillan shared the Nobel Prize in Chemistry with Seaborg "for their discoveries in the chemistry of the transuranium elements".[16]

World War II

Edwin McMillan Los Alamos badge

McMillan's abrupt departure was caused by the outbreak of

Yale Medical School.[1] Her sister Mary was Lawrence's wife.[19] The McMillans had three children: Ann Bradford, David Mattison and Stephen Walker.[1][20]

McMillan joined the Navy Radio and Sound Laboratory near San Diego in August 1941. There he worked on a device called a polyscope. The idea, which came from Lawrence, was to use sonar to build up a visual image of the surrounding water. This proved to be far more difficult that doing so with radar, because of objects in the water and variations in water temperature that caused variations in the speed of sound. The polyscope proved to be impractical, and was abandoned. He also, however, developed a sonar training device for submariners, for which he received a patent.[17][21][15]

Oppenheimer recruited McMillan to join the

John H. Manley, he drew up the specifications for the new laboratory's technical buildings.[23] He recruited personnel for the laboratory, including Richard Feynman and Robert R. Wilson, established the test area known as the Anchor Ranch, and scoured the country for technical equipment from machine tools to a cyclotron.[24]

As the laboratory took shape, McMillan became deputy head of the

implosion-type nuclear weapon. McMillan took an early interest in this, watching tests of this concept conducted by Seth Neddermeyer. The results were not encouraging. Simple explosions resulted in distorted shapes.[26] John von Neumann looked at the implosion program in September 1943, and proposed a radical solution involving explosive lenses. This would require expertise in explosives, and McMillan urged Oppenheimer to bring in George Kistiakowsky.[27]
Kistiakowsky joined the laboratory on February 16, 1944, and Parsons's E (Explosives) Division was divided in two, with McMillan as deputy for the gun and Kistiakowsky as deputy for implosion. [28]

McMillan heard disturbing news in April 1944, and drove out to Pajarito Canyon to confer with Segrè. Segrè's group had tested samples of plutonium bred in the Manhattan Project's nuclear reactors and found that it contained quantities of plutonium-240, an isotope that caused spontaneous fission, making Thin Man impractical.[29] In July 1944, Oppenheimer reorganised the laboratory to make an all-out effort on implosion. McMillan remained in charge of the gun-type weapon,[30] which would now be used only with uranium-235. This being the case, Thin Man was replaced by a new, scaled-back design called Little Boy.[31] McMillan was also involved with the implosion as the head of the G-3 Group within the G (Gadget) Division, which was responsible for obtaining measurements and timings on implosion,[32] and served as the laboratory's liaison with Project Camel, the aerial test program being carried out by Caltech. On July 16, 1945, he was present at the Trinity nuclear test, when the first implosion bomb was successfully detonated.[33]

Later life

Mark Oliphant (left) with McMillan, 1965

In June 1945, McMillan's thoughts began to return to cyclotrons. Over time they had gotten larger and larger. A 184-inch cyclotron was under construction at the Radiation Laboratory, but he realised that a more efficient use could be made of the energy used to accelerate particles. By varying the magnetic field used, the particles could be made to move in stable orbits, and higher energies achieved with the same energy input. He dubbed this the "phase stability principle", and the new design a "synchrotron".[34][35] Unknown to McMillan, the synchrotron principle had already been invented by Vladimir Veksler, who had published his proposal in 1944.[36] McMillan became aware of Veksler's paper in October 1945.[17] The two began corresponding, and eventually became friends. In 1963 they shared the Atoms for Peace Award for the invention of the synchrotron.[37] In 1964, McMillan received the Golden Plate Award of the American Academy of Achievement.[38]

The phase stability principle was tested with the old 37-inch cyclotron at Berkeley after McMillan returned to the Radiation Laboratory in September 1945. When it was found to work, the 184-inch cyclotron was similarly modified.[34][17] He became a full professor in 1946. In 1954 he was appointed associate director of the Radiation Laboratory. He was promoted to deputy director in 1958. On the death of Lawrence that year, he became director, and he stayed in that position until his retirement in 1973. The laboratory was renamed the Lawrence Radiation Laboratory in 1958. In 1970, it split into the Lawrence Berkeley Laboratory and the Lawrence Livermore Laboratory, and McMillan became director of the former.[1][37][39]

McMillan was elected to the

National Academy of Sciences in 1947, serving as its chairman from 1968 to 1971.[40] He was elected to the American Philosophical Society in 1952.[41] He served on the influential General Advisory Committee (GAC) of the Atomic Energy Commission from 1954 to 1958, and the Commission on High Energy Physics of the International Union of Pure and Applied Physics from 1960 to 1967.[42] He was elected to the American Academy of Arts and Sciences in 1962.[43] After his retirement from the faculty at Berkeley in 1974, he spent 1974–75 at CERN, where he worked on the g minus 2 experiment to measure the magnetic moment of the muon. He was awarded the National Medal of Science in 1990.[37]

McMillan suffered the first of a series of strokes in 1984.

The Smithsonian, in Washington DC.[44]

Publications

Notes

  1. ^ a b c d e f Nobel Foundation. "Edwin M. McMillan – Biographical". Retrieved July 16, 2015.
  2. ^ a b c "Edwin McMillan – Session I". American Institute of Physics. March 19, 2015. Retrieved July 16, 2015.
  3. ^ Seaborg 1993, p. 287.
  4. doi:10.7907/9G6C-HC68
    . Retrieved July 16, 2015.
  5. OCLC 77699392 – via ProQuest
    .
  6. ^ a b c Seaborg 1993, p. 288.
  7. ^ a b Lofgren, Abelson & Helmolz 1992, pp. 118–119.
  8. ^ a b Jackson & Panofsky 1996, pp. 217–218.
  9. ^ Jackson & Panofsky 1996, pp. 218–219.
  10. ^ "Chart of Nuclides: 10Be information". National Nuclear Data Center, Brookhaven National Laboratory. Archived from the original on July 12, 2017. Retrieved July 18, 2015.
  11. ^ Jackson & Panofsky 1996, pp. 221–222.
  12. ^ a b Jackson & Panofsky 1996, pp. 221–223.
  13. doi:10.1103/PhysRev.55.1104
    .
  14. doi:10.1103/PhysRev.57.1185.2
    .
  15. ^ a b Seaborg 1993, p. 289.
  16. ^ Nobel Foundation. "The Nobel Prize in Chemistry 1951". Retrieved July 16, 2015.
  17. ^ a b c d e f "Edwin McMillan – Session IIII". American Institute of Physics. March 19, 2015. Retrieved July 16, 2015.
  18. ^ Seaborg 1993, p. 291.
  19. ^ Jackson & Panofsky 1996, p. 216.
  20. ^ a b Lambert, Bruce (September 9, 1991). "Edwin McMillan, Nobel Laureate And Chemistry Pioneer, Dies at 83". The New York Times. Retrieved July 16, 2015.
  21. ^ U.S. patent 2,694,868
  22. ^ Rhodes 1986, pp. 449–451.
  23. ^ Hoddeson et al. 1993, p. 62.
  24. ^ a b Hoddeson et al. 1993, p. 84.
  25. ^ Hoddeson et al. 1993, p. 114.
  26. ^ Rhodes 1986, pp. 477–479, 541.
  27. ^ Hoddeson et al. 1993, pp. 130–133.
  28. ^ Hoddeson et al. 1993, p. 139.
  29. ^ Hoddeson et al. 1993, pp. 238–239.
  30. ^ Hoddeson et al. 1993, p. 245.
  31. ^ Hoddeson et al. 1993, pp. 256–257.
  32. ^ Hoddeson et al. 1993, pp. 272–273.
  33. ^ Jackson & Panofsky 1996, p. 225.
  34. ^ a b Jackson & Panofsky 1996, pp. 226–227.
  35. doi:10.1103/PhysRev.68.143
    .
  36. Comptes Rendus de l'Académie des Sciences de l'URSS
    . 43 (8): 329–331.
  37. ^
    Lawrence Berkeley Laboratory. Archived from the original
    (PDF) on July 23, 2015. Retrieved July 18, 2015.
  38. American Academy of Achievement
    .
  39. ^ Jackson & Panofsky 1996, p. 230.
  40. ^ "Edwin M. McMillan". www.nasonline.org. Retrieved February 6, 2023.
  41. ^ "APS Member History". search.amphilsoc.org. Retrieved February 6, 2023.
  42. ^ Seaborg 1993, pp. 290–291.
  43. ^ "Edwin Mattison McMillan". American Academy of Arts & Sciences. Retrieved February 6, 2023.
  44. ^ "Nobel Prize Medal in Chemistry for Edwin McMillan". National Museum of American History, Smithsonian Institution. Retrieved July 18, 2015.

References

External links

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