Ralph Marks Moon Jr, a world leader in the use of neutron-scattering techniques to investigate the properties of materials, died of cancer on 1 June 2004 at his home in Oak Ridge, Tennessee.
Ralph was born in Bombay, India, on 11 October 1929. His family returned to the US in 1931 and settled in Kansas City, Missouri, where Ralph received his early education in the public schools. He attended the University of Kansas in Lawrence and earned his BA (1950) and MA (1952), both in physics.
Ralph subsequently spent two years at the US Naval Ordnance Test Station in China Lake, California, doing research on the physical properties of rocket propellants. He left that position in 1954 to enter military service and served three years in the US Navy as a guided-missile officer. In 1958, he entered graduate school at MIT, where he also worked as a staff associate at the Lincoln Laboratory. He carried out his thesis research, which involved using neutron scattering to determine the magnetic-moment distribution in hexagonal cobalt, under the direction of Clifford Shull, who would later receive the Nobel Prize in Physics (see Shull’s obituary in Physics Today, October 2001, page 86). Ralph earned his PhD in physics from MIT in 1963. He joined the staff of the Oak Ridge National Laboratory (ORNL) in 1963.
From the beginning of his career, Ralph was an outstanding scientist who maintained exceptionally high standards in the quality of his work. He did not like to do anything superficially; he wanted to understand a problem completely, plan the best course of action, and carry it to a successful conclusion. Although primarily an experimentalist, he had a very good understanding of solid-state theory, and his combination of skills produced excellent research.
Most of Ralph’s scientific contributions involved the applications of neutron-scattering techniques to magnetic materials, and his work added to the overall understanding of magnetism. His precise measurements, by polarized neutron scattering, of magnetic form factors established a new standard for that type of research and provided valuable information on the outer atomic electrons responsible for interesting chemical and physical properties of materials.
Ralph’s research was driven by his interest in discovering new techniques. His most important and ingenious work was the development, in 1969, of the neutron-polarization analysis technique, in collaboration with Tormod Riste, a visiting scientist from Kjeller, Norway, and Wallace Koehler of ORNL. This technique permits the accurate separation of magnetic scattering from nuclear scattering, and it is used in neutron centers worldwide to study many different classes of materials.
Some of Ralph’s most important contributions to science, however, came from management responsibilities that he was willing to accept. He became head of the neutron scattering program in ORNL’s solid-state division (now the condensed matter sciences division) in 1985, acting division director in 1992, and associate division director in 1993. Under his leadership, scientists from other organizations and ORNL established several collaborative programs in neutron scattering. One of the most significant, involving a collaboration between scientists from the US and Japan, was initiated under the US–Japan Agreement on Cooperation in Research and Development in Science and Technology that was signed in 1980. The neutron scattering program began in 1981 and continues today as a highly successful model for international research cooperation. After his retirement in 1994, Ralph continued to work at ORNL as a consultant and helped with upgrades of research instruments at the High Flux Isotope Reactor.
Ralph made widely recognized contributions to the scientific community as a leader on several important national committees, panels, and workshops. Many of those activities were associated with his interest in and hard work promoting a new high-intensity neutron source for the US. That effort, begun in the 1970s, laid the foundation for the approval of the Spallation Neutron Source now under construction at ORNL.
In addition to his extraordinary technical competence, Ralph possessed an unusual combination of integrity, honesty, and talent for calm analysis that earned him respect and admiration among his peers. He was an exceptionally nice person, and he had many friends in universities and research centers throughout the world. All of his friends miss him very much.
