SNS upgrade accelerates neutron research, boosts data quality

During its 20 years of operations, SNS has become the world-leading user facility for neutron scattering experiments to investigate the structure and dynamics of materials. The completed proton power upgrade ensures SNS will remain the world's most powerful proton accelerator to support future discoveries in materials and the life sciences.

Many experiments and analyses are faster

Instead of needing days or weeks of beam time to collect data, some scientists can now complete the same number of measurements in just 1 to 12 hours. ORNL's data reduction system also makes it easier to analyze the results of the experiments, so researchers can publish their papers or complete their master's theses and doctoral dissertations sooner.

The experimental data is better

Instead of having to settle for static "snapshots" of the materials they are studying, researchers can now take the time to rotate their samples within the beam to produce slow-motion "movies" that for the first time capture details of many atomic- and molecular-scale activities within the materials, including phase transitions as a material changes from one physical state to another. They can also do this with higher sensitivity in a wider range of sample environments, including extreme temperatures, pressures and magnetic fields.

Sample sizes can be much smaller

In the past, sample sizes for accurate experiments needed to be relatively large compared to other diagnostic techniques, such as X-ray diffraction. It was not uncommon for it to take weeks or months to grow a sample into a sufficiently large crystal to use in experiments - if a large crystal could be grown at all. Now some samples used for neutron experiments at SNS can be as small as those used in X-ray diffraction (100 x 200 microns, or just at the edge of human vision capability), but with the added benefit that neutrons can identify hydrogen atoms and measure their quantities, which X-rays cannot do with much accuracy.

Experiments can include more kinds of materials

The capability of using much smaller sample sizes and obtaining improved data also enables researchers to use neutrons to study a wider range of new and exotic materials.

ORNL's Christina Hoffmann, an instrument scientist for TOPAZ, a high-resolution single-crystal diffractometer at SNS, said, "We are now able to study samples of new and exciting materials that were previously too small to use in our experiments. This enables insight into materials behavior to pave the way for many new and important discoveries and new applications, such as in the mineral, chemical, medical, industrial and national security fields."

More "mail-in" experiments are possible

Depending on the instrument, shorter experiment times can mean more time for SNS instrument scientists to assist external users who are able to mail in their samples. "We've already been able to expand our mail-in capabilities to nine instruments here at SNS," said Matthew Stone, one of the scientists responsible for the SEQUOIA instrument, a fine-resolution Fermi chopper spectrometer. "The increased proton power has really made a big difference in our ability to respond to scientific proposals in general."

Eventually the linac will also power the planned Second Target Station to provide the world's brightest "cold" neutrons. STS will complement the FTS by filling gaps in materials research that require the combined use of intense, cold (longer wavelength) neutrons and instruments that are optimized for exploring more complex materials.

The STS, along with the FTS and ORNL's High Flux Isotope Reactor (HFIR), the world's most powerful reactor-based neutron source, will together help ensure the U.S. maintains its global leadership in the neutron sciences.

SNS and HFIR are DOE Office of Science user facilities.

UT-Battelle manages ORNL for the Department of Energy's Office of Science, the single largest supporter of basic research in the physical sciences in the United States. The Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science.
- Paul Boisvert