The American physicist James Rainwater (1917–1986) earned the Nobel Prize in Physics in 1975 for his work on the structure of atomic nuclei. Although Rainwater's work was theoretical, his knowledge of atomic physics was developed in the realm of practical applications: as a graduate student at Columbia University during World War II, he worked on the so-called Manhattan Project that produced the atomic bomb.
James Rainwater came of age at a time when the work of talented scientists would define world history. Given the first name Leo by his parents, Leo J. and Edna Teague Rainwater, Rainwater was born in the small ranching and lumbering town of Council, Idaho, on December 9, 1917. His parents moved there so his father could find work as a civil engineer, but he ultimately opened a small general store. In late 1918 the deadly influenza epidemic of that year came to Council, killing Leo Rainwater and almost killing his infant son. After the child recovered, he moved with his mother to Hanford, California. She eventually remarried, and Rainwater attended schools in Hanford, excelling in scientific subjects.
Rainwater entered Columbia's physics program at an extraordinary time: Leading European theoretical physicists Edward Teller (1908–2003) and Enrico Fermi (1901–1954), had fled fascism in Europe and were now on Columbia's faculty. Rainwater studied with both men during his first two years at Columbia, earning an M.A. degree in 1941 and absorbing the cutting-edge work in atomic physics that would lead directly to the development of the atomic bomb during World War II under the code name “the Manhattan Project.” The cyclotron particle accelerator that made possible the study of the behavior of atomic particles was a new invention at the time, and Rainwater and two other graduate students, W.W. Havens, Jr., and C.S. Wu, joined faculty supervisor John Dunning in deriving a technique called pulsed neutron spectroscopy—the examination of the behavior of neutrons as an atom is broken up—in order to draw conclusions about the structure of other components of the atom. Because it involved the national defense of a nation at war, Rainwater's work was classified as secret. As a result, his degree was delayed until 1946, when this research was declassified.
After receiving his degree, Rainwater stayed on at Columbia University as an instructor. He spent his entire career there, rising to the post of associate professor of physics during the late 1940s and full professor in 1952. He was director of the university's Nevis Laboratories from 1951 to 1954 and again from 1957 to 1961; a central feature of the lab was an improved particle accelerator—called a synchrocyclotron—which construction Rainwater was directly involved. Meanwhile, in 1942 Rainwater had married Barnard University graduate Louise Smith. The couple would raise three sons, James, Robert, and William, as well as a daughter, Elizabeth Ann, who died of childhood leukemia at age nine.
As part of his job at Columbia, Rainwater supervised several talented graduate students during the late 1940s and early 1950s. The work for which he became best known grew out of conversations with such students, as well as with a visiting Danish professor, Aage Bohr, the son of famed theoretical physicist Niels Bohr. Rainwater oversaw a key graduate seminar in advanced atomic physics, and the research conducted by this group, particularly by Rainwater himself, achieved several major breakthroughs in understanding the structure of the atom. A particular piece of luck was that Rainwater and Bohr shared an office during the 1949–1950 academic year.
At the time, scientists were beginning to explore in detail the structure of the atomic nucleus, the dense collection of protons and neutrons at the center of an atom. In fact, protons and neurons had only recently been discovered, in 1932. It was known that the nucleus existed and exerted electric forces on the protons and neutrons that composed it, but its exact configuration remained a matter of speculation. Did the nucleus, as Niels Bohr suggested, shift shape like a drop of liquid? Or was it composed, as Maria Goepert Meyer and Hans D. Jensen argued, of concentric shells in which protons and neutrons, like electrons farther out, circled the nucleus in orbits? The latter was the dominant view, but experiments in the 1940s showed that the electrical charge exerted by the nucleus was not spherical in form, but some other as yet undetermined shape.
In 1949, after attending a lecture summarizing the differences between and the inadequacy of the existing models, Rainwater hit on a key idea: centrifugal forces of objects moving within the nucleus might deform the supposed sphere into an ellipsoid, a shape essentially like that of a football. Publishing his hypothesis in a 1950 paper, he continued to discuss it with Aage Bohr, who, back in Denmark, worked with fellow Dane Ben Mottelson to devise new experiments leading to a comprehensive theory of the structure of the nucleus. Their conclusion combined the shell model with Niels Bohr's drop-of-liquid model, asserting that if the outer shell of the nucleus did not have a full set of nucleons (subatomic particles in the nucleus), the nucleus would take on the football shape. If the outer shell had all the nucleons possible, however, the nucleus would be spherical.
Rainwater was devoted to his work and tended to avoid social interactions and athletic activities. On hearing that a departmental holiday party had been canceled, he was reported by Fitch as commenting, “Good. Now if only [fellow faculty member] Quimby would cancel his New Year's Eve party, we could get a lot of work done.” Rainwater was described as modest about his own accomplishments and interested in deeper questions rather than hot academic topics. In Fitch's words, “Hot items in the marketplace of physics were not for him. He was too reflective for that. He had to understand things at too deep a level. He eschewed the superficial, he disdained the dilettante. It was not obvious disdain. He simply observed and walked away. He was not given to small talk.”
Building on his groundbreaking discoveries, Rainwater continued to study subatomic particles and produced several more pieces of important research. He was interested in the new subatomic particles that could be studied through the use of Columbia's new synchrocyclotron, especially the muon, discovered in 1936 by Rainwater's mentor Carl Anderson at Caltech. The muon is a fast-decaying particle that exerted a force that helped bind the atomic nucleus together. His work showed that the size of protons had been overestimated up to that time, and he discovered new aspects of the behavior of neutrons.
Rainwater's model for the shape and structure of the nucleus was not universally accepted, and in his lecture given when he won the Nobel Prize he made a point of saying that other physicist had not recognized the importance of his work at first. By the 1970s, however, its fundamental status had become clear. Rainwater continued to work with the synchrocyclotron through the late 1950s and 1960s, producing several more important discoveries and supervising the work of Fitch and several other intellectually innovative graduate students. He continued to work with the cyclotron until it was taken out of use in 1978, and thereafter returned to full-time teaching.
Rainwater received several other significant honors in addition to the Nobel Prize: he won the Ernest Orlando Lawrence Award of the Atomic Energy Commission in 1963, was admitted to the National Academy of Sciences in 1968, and was awarded an honorary membership in the Swedish Academy of Sciences, which grants the Nobel Prize, in 1982. His health declined in later years, but he insisted on continuing to teach. In early 1985, after leaving the hall where he had just completed a lecture, Rainwater collapsed. A student successfully administered cardiopulmonary resuscitation, but his poor health forced him to retire. Rainwater died on May 31, 1986, in Yonkers, New York.
New York Times, June 3, 1986.
Physics Today, October 1986, p. 140.
American Institute of Physics website, http://history.aip.org/ (November 29, 2016), “James Rainwater.”
National Academy of Sciences website, http://www.nasonline.org/ (November 29, 2016), “James Rainwater, 1917–1986.”
Nobel Prize website, http://www.nobelprize.org/ (November 29, 2016), “James Rainwater.”.❑