SIDEBAR: Getting every last detail

By Gary Goettling

By enabling Georgia Tech researchers to investigate the structure and behavior of materials in astonishing new detail, the Spallation Neutron Source (SNS) under construction at Oak Ridge, Tenn., holds the potential to do for science and engineering what the Hubble Space Telescope has done to advance astronomy.

The $1.4 billion, federally funded SNS is a partnership between the U.S. Department of Energy and its six national laboratories. The facility will be located on a 110-acre site within the Oak Ridge National Laboratory complex. Scheduled for completion in 2006, SNS's 30 to 40 experimental areas will accommodate up to 2,000 projects a year from scientists in academia, government laboratories and industry. The SNS will provide the most powerful pulsed neutron sources in the world and give scientists detailed snapshots of the structure of even the smallest samples of physical and biological materials at macromolecular through subatomic levels.

"The Spallation Neutron Source is going to become one of the world's premiere facilities for science research, and Oak Ridge is looking to Georgia Tech to be one of the institutions that will drive its use," says Dr. Wayne Clough, president of the Georgia Institute of Technologywith the SNS.neen named Georgia. Tech is one of six universities recently appointed to manage the focused research programs at Oak Ridge National Laboratory.

Dr. Gary B. Schuster, dean of the College of Sciences, notes that the SNS's practical applications will be matched by its potential to make new discoveries into the nature of condensed matter. As the most powerful instrument of its kind ever built, SNS-assisted research is likely to have a far-reaching impact no one can foresee.

"Science progresses as a consequence of the availability of tools," Schuster says. "Tools make experiments possible, and experiments make it possible to address ever-more sophisticated questions. Sometimes the answers to these sophisticated questions lead to unexpected results."

Serving as Georgia Tech's point man in the new research-management side of its relationship with Oak Ridge is Dr. Charles L. Liotta, vice provost for research, dean of graduate students and Regents' professor of chemistry and biochemistry.

"For our research faculty to have access to the Spallation Neutron Source could be a tremendous jump for Georgia Tech scientists and engineers in their research," he says. "The Spallation Neutron Source allows new questions to be addressed about the structure of materials and the structure of complicated materials. The answers to these questions will have a great impact in the areas of biotechnology, telecommunications and environmental technology."

In short, the SNS is a facility where objects are bombarded with pulses of neutrons. The pattern of diffraction or scattering by the neutrons as they pass through the object provides researchers with considerable information. Neutrons can reveal microscopic details about the underlying structure and dynamics of a sample. They are useful for probing the positions of atoms in both liquids and solids, and offer great sensitivity to magnetism. The technique is non-destructive, even to complex, delicate, polymeric or biological materials.

By analyzing the ways in which neutrons are diffused through an object, "you can deduce lots of things about how materials are going to behave under real-world conditions and make predictions that will help you improve products in some cases," says Dr. Angus Wilkinson, an associate professor of chemistry and biochemistry who has been named Georgia Tech's liaison with the SNS.

For years, neutron scattering has played a key role in the development of an astonishing array of products ranging from compact discs and magnetic information-storage devices to shatterproof windshield glass, bullet-proof vests, plastic automobile bumpers and medical isotopes that have led to life-saving treatments and diagnostic techniques for cancer. Neutron research also helps scientists improve materials used in high-temperature superconductors, powerful lightweight magnets, aluminum bridge decks and stronger, lighter plastic products.

The SNS is a versatile tool likely to affect a range of science and engineering research at Georgia Tech, Wilkinson predicts.

"I think we're going to see an impact in structural biology, materials science both in ceramics and metals, chemical engineering, textiles and polymer science," he says.

An accelerated source produces neutrons through spallation, which means neutrons are knocked out of a heavy metal target. The process begins with negatively charged hydrogen ions—one proton orbited by two electrons—injected into a linear accelerator. The high-energy ions pass through a foil that strips off the two electrons, and the remaining protons accumulate inside a ring. The protons are released from the ring in pulses that strike a heavy metal target. (The SNS will use mercury.) Corresponding pulses of neutrons are ejected from the target, slowed down in a moderator and guided through beam lines to areas containing the samples and neutron detectors.

The SNS will produce a neutron beam 10 times the intensity of the present top-of-the-line facility, a spallation source located near Oxford, England, known as ISIS.

Among Georgia Tech's advantages, Wilkinson says, is the proximity of Atlanta to Oak Ridge. A four-hour drive puts the SNS within easy reach of faculty and graduate students, and convenient access also means more collaborative work can be done there.

"It's hard to maintain a good working relationship when you rarely meet the people you're working with," Wilkinson observes. "Here we should be able to communicate better and plan better what we're going to do and cooperate more readily with the people who are at the facility."

For more information: Dr. Angus Wilkinson, School of Chemistry and Biochemistry, Georgia Tech, Atlanta, GA 30332-0400. Tel: 404-894-4036. Email: angus.wilkinson@chemistry.gatech.edu.

Source: Georgia Tech