George Wells Farwell, who spent almost all of his professional life at the University of Washington, died in Seattle on 11 April 2003. His major physics contributions were in studies of spontaneous fission of plutonium, alpha particle scattering, time-reversal invariance, and applications of accelerator mass spectrometry.
Farwell was born in Seattle on 15 February 1920. He received a bachelor’s degree in physics from Harvard University in 1941 and went on to graduate studies at Berkeley, where he joined the group headed by Emilio Segrè. After the start of World War II, he moved with Segrè to Los Alamos, where he and other Segrè graduate students (including Owen Chamberlain and Clyde Wiegand) carried out the measurements that established the high rate of spontaneous fission in plutonium-240. That finding motivated the development of the implosion method for plutonium bombs. Chamberlain, Farwell, and Segrè are recognized as the codiscoverers of 240Pu.
After leaving Los Alamos, Farwell continued his graduate studies at the University of Chicago and completed his PhD thesis in 1948 under the direction of Enrico Fermi. The thesis, on spontaneous fission in plutonium, was based largely on the Los Alamos work. He then joined the faculty of the University of Washington, where a nuclear physics program was being started and initially was centered around the construction of a 60-inch cyclotron. Farwell took special responsibility for the development of the magnet system that provided external particle beams.
In one of the first uses of those beams, Farwell and his students studied the elastic scattering of helium-4 nuclei from a broad range of medium and heavy nuclei. As in Ernest Rutherford’s classic experiment on the lightest nuclei, Farwell and his group deduced the values of the nuclear radii from the way that the angular distributions dropped below the expectations for pure Coulomb scattering. Using a strong-absorption model developed by his colleague John S. Blair, Farwell was able to determine the values of effective nuclear radii to a few percent. Those precise values confirmed that the radii tracked linearly with the one-third power of the atomic mass. However, the precision revealed significant departures from that relation for certain nuclei; those departures were ultimately explained by consequences of nuclear shell structure.
Somewhat later, Farwell and physics department colleagues undertook a study of time-reversal invariance in strong interactions, in which they measured angular distributions to the ground state for the inverse reactions 12C(α, d)14N and 14N(d,α)12C. They found that the two distributions were identical to within experimental uncertainties. That finding indicated that the time-reversal noninvariant fraction of the strong-interaction Hamiltonian was probably less than 3%. In 1959, when their results were published in Physical Review Letters, that was the most precise limit.
For nearly 20 years, starting in 1959, Farwell directed part or all of his professional efforts to university administrative activities, including service as the university’s assistant vice president (1965–67) and as vice president for research (1967–76). He played an important part in facilitating the expansion of scientific research programs. He took a particular interest in programs related to marine sciences and served in 1967 as acting director of the university’s newly established Center for Marine Research.
In 1977, Farwell once again became a full-time member of the physics department. He and his long-time colleague Fred H. Schmidt started up a program in accelerator mass spectrometry. A number of their studies, done in collaboration with colleagues from other departments, focused on transport of carbon in nature. One study measured the finescale variations of the 14C concentration in Galapagos Island coral that reflect similar variations in the local waters. The changes in the island’s coral arise from seasonal changes in the admixed fraction of water from the deep ocean, where the carbon is thousands of years old. A similar finegrained study exploited the spike in the 14C content of the atmosphere that resulted from the 1962–63 nuclear bomb tests. Farwell and his colleagues found a several-month lag of the 14C concentration in the rings in Sitka spruce trees compared with that in the atmosphere. Their finding suggested either a slow processing of the atmospheric carbon that went into forming the Sitka cellulose or the incorporation of earlier stored carbon. The bomb-test spike was also useful in a study of 14C concentrations in the Amazon River; that study determined carbon retention times in bordering plants and soil.
Farwell spent the 1960–61 year at the Bohr Institute in Copenhagen as an NSF senior postdoctoral fellow. Later, in addition to his activities at Washington, he served as a trustee of the Universities Space Research Association (1969–76). On occasion, Farwell undertook brief investigations of matters outside his main fields of professional interest. For example, he studied the persistence of memory of musical tones. He also had the special pleasure of collaborating with his son, Lawrence Farwell (a neuroscientist), on a study of consciousness and with his daughter, Jacqueline Farwell (a neurologist), on a study of brain tumor survival rates.
Seattle is surrounded by mountains and water, and George, who was a skilled climber, skier, and boatsman, enthusiastically took advantage of their accessibility. He was actively interested in the broader community and served as a trustee of the Pacific Science Center and as a director of the King Broadcasting Co in Seattle.
Farwell had a wide spectrum of interests, abilities, and contributions. With his death, his colleagues and many in the larger community have lost a valued friend.
