The SNS is attracting research beyond conventional physics.
One of the Spallation Neutron Source's most far-reaching contributions is its ability to bridge research disciplines and to uncover new perspectives on inquiries conducted across the breadth of the scientific spectrum. The real value of the SNS extends beyond providing physicists with an unmatched ability to peer into the structure of materials. Of even greater consequence, the SNS enables scientists from fields as diverse as chemistry, biology and geology to investigate materials, tissues, and processes in ways that might never have been contemplated had the scope of research been limited to conventional physics.
"Many laboratory programs—whether fundamental science, applied science, or working with industry—rely on neutrons to gather data about the materials they use," says Michelle Buchanan, ORNL's Associate Laboratory Director for Physical Sciences. "At Oak Ridge, because we have historic ties with neutron science, a lot of people at the laboratory in a variety of fields are ‘fluent' in neutrons."
Buchannan points to two Energy Frontier Research Centers (EFRCs) recently established at ORNL that will further strengthen the synergy between neutron science and these allied fields. "The SNS is pushing several areas of inquiry," Buchanan says. "One is the study of materials under extreme conditions, such as high radiation, strain and stress, temperature, and pressure. Another is investigating interfaces. Both of the EFRCs fall under these umbrellas, so the synergy among disciplines is there as well."
One of the EFRCs, the Center for Fluid Interface Reactions, Structures and Transport, brings together a multidisciplinary research team of laboratories and universities to concentrate on issues related to energy storage and related material properties. The center will have access to the neutron scattering capabilities of the SNS to look at interfacial phenomena, such as how liquids interact with surfaces. Buchanan observes that, "While most people think of a fluid-solid interface as two distinct phases, there are actually incredibly rich chemical and physical processes going on between them."
Understanding how fluids and solid materials interface at a subatomic level will be critical to achieving breakthroughs in key energy technologies, such as improved batteries, solar panels and fuel cells. The new perspectives would also have implications for other energy-related research, such as carbon dioxide sequestration, catalysis and the development of corrosion-resistant materials.
"For example," Buchanan says, "scientists don't understand exactly what makes a battery fail. The liquid-solid interface in batteries is incredibly complex—and with every charge and discharge of a battery, the interface changes. By understanding the changes that happen at that interface, batteries could be designed to be safer and last longer."
ORNL's second EFRC, the Center for Defect Physics in Structural Materials, is also closely aligned with the SNS. This center will bring together researchers from ORNL, six universities and Lawrence Livermore National Laboratory to develop techniques for detecting and correcting microscopic defects in materials and thus develop new materials with unprecedented strength and durability.
A large portion of the center's research will use high-resolution instruments at the SNS to locate and characterize flaws in materials, to determine how they evolve into clusters of defects that eventually become cracks and ultimately lead to failure.
"Whether researchers are working with small solar cells or enormous reactor vessels," Buchanan says, "the goal is the ability to understand these defects and to control them. Knowing what causes a material to fail is critical to preventing future failures. In the case of nuclear reactor vessels, this knowledge can make the difference between vessels with a 30- or 40-year lifetime and vessels with a lifetime of 80 to 100 years."
In scientific terms, research synergy is not a one-way street. The same disciplines that benefit from the analytical abilities of the SNS also exert pressure on the facility to expand its capabilities, sometimes in unexpected directions. "As the SNS instruments are established," Buchanan says, "our scientists sometimes find that they need new capabilities to accommodate a broader range of research than was envisioned when the instruments were originally designed."
One illustration of this influence is a project in which materials science researchers are working with SNS staff to develop new optics that will enable the SNS to focus neutrons beams on smaller areas. This process will enable them to see minute battery components or biological samples in much greater detail than previously possible.
Similarly, polymer scientists are interested in developing experimental chambers that would enable the study of polymers that self-assemble to make unique structures. Buchanan believes understanding how such assembly occurs would be fascinating to scientists. "Because the neutron beam at the SNS is pulsed, instruments can provide time-lapse views of the interactions among these polymers. This would allow us to get a view of how self-assembly happens, rather than just seeing ‘before and after' snapshots of the process."
Buchanan credits much of the interdisciplinary appeal of the SNS to the laboratory's concerted effort to reach across research programs and initiate collaboration with neutron scientists. As evidence of the success of this approach, Buchanan notes that one of the first papers published as a result of research conducted at the SNS was led by geochemists. "Now it's not unusual to see papers on neutron scattering authored by people who are not neutron experts."
While the wide applicability of the SNS as a research tool has been a revelation to some, the potential was apparent at the facility's inception. "I remember the first announcement of plans to build the SNS," Buchanan recalls. "Former ORNL Associate Director Bill Appleton surprised a number of people when he said the SNS would be a critical tool for chemistry." She recalls everyone knew the machine would be applicable to all sorts of applied and fundamental materials science research, but few considered the range of areas that would be supported by the SNS.
"Ten years ago, almost no one thought that chemists would be involved in neutron science. Now I am amazed by the things we can do with neutrons that give us insights into molecular interactions, dynamics and structure. In chemistry and a number of other fields, we are just beginning to see what may be possible."
Buchanan emphasizes that the key to the synergistic relationship between the SNS and research programs across the laboratory is communication and cooperation. "Our problems motivate the folks at the SNS to look for solutions," she says, "and in turn their innovations encourage us to use techniques that we would not have thought about otherwise. We're pushing each other, and the result is new approaches to research."
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