75 years of science and technology
Ernest O. Wollan came to Oak Ridge from the University of Chicago as part of the top-secret Manhattan Project, but he had other ideas on what he could do with the world’s first operating nuclear reactor.
“I would like to attempt to measure the diffraction of neutrons by single crystals,” he wrote in a memo on May 25, 1944.
Wollan suspected neutron scattering might be useful for research, similar to X-ray diffraction. He was joined in 1946 by a young scientist named Clifford Shull, and the two used ORNL’s Graphite Reactor to lay the groundwork for the fundamental principles of elastic neutron scattering.
The ORNL team was the first to measure neutron Laue patterns—regularly spaced spots—in single crystals. They opened a new understanding of magnetic materials and the magnetic properties of neutrons, and they developed some of the first powder diffraction analytical techniques to study them.
Neutron scattering research at ORNL continued, particularly at the Oak Ridge Research Reactor and later at the High Flux Isotope Reactor. But by the late 1980s the United States trailed in neutron science. Because of neutron science’s role in the development of advanced materials, this was of economic concern.
Two events turned the tide: Shull shared the Nobel Prize for his early ORNL work in neutron scattering in 1994, and shortly thereafter, DOE announced plans to build a new neutron source at ORNL, a solution less costly than a new nuclear reactor.
At a design power of 1.4 megawatts, the Spallation Neutron Source, combined with the refurbished HFIR, reclaimed preeminence in neutron scattering research for ORNL, where neutron analysis was initially conceived in a now-yellowed wartime memo.
