Physicist James A. Van Allen died at the age of 91 on August 9 in Iowa City. He was a long-time professor of physics and astronomy at the University of Iowa and was associated with the Carnegie Institution of Washington early in his career.

Van Allen received his Ph.D. from the University of Iowa in June 1939 and joined DTM two months later as a Carnegie Research Fellow. At the time DTM was a world-class center for nuclear physics, with Merle Tuve as its driving force. During 1939-1940 Van Allen worked with Nicholas Smith here on the photodisintegration of deuterium by gamma rays, and with Norman Ramsay on measuring neutron-proton cross sections using a proportional counter that he devised for observing recoil protons.

As Van Allen pointed out in his 1990 autobiography, “of much greater importance to my future career was my crossing of the culture gap at DTM from nuclear physics to the department’s traditional research in geomagnetism, cosmic rays, auroral physics, and ionospheric physics.” Under the influence of researchers like Scott Forbush, Harry Vestine, Sydney Chapman, and Julius Bartels, Van Allen’s interest in low-energy nuclear physics dwindled. As he put it, “I resolved to make geomagnetism, cosmic rays, and solar-terrestrial physics my fields of research.” But that transformation had to await the completion of Van Allen’s significant wartime contributions.

In the summer of 1940, he joined DTM’s national defense efforts and was appointed to a staff position in “Section T” where he worked on the development of photoelectric and radio proximity fuzes. In April 1942, with the transfer of fuze work to the Applied Physics Laboratory of Johns Hopkins University, he left Carnegie. He was associated with APL until 1950; most of his subsequent, illustrious career was spent at the University of Iowa. His 1958 discovery of zones of energetic charged particles surrounding the Earth, the “Van Allen radiation belts,” was the first major scientific advance of the Space Age and ushered in the new field of magnetospheric physics.

Related Links: New York Times Obituary and The Washington Post article