Desert Neutrons

Neutron scattering technology

4 March 2016

Professor Xun Li Wang is the Chair Professor and Head of the Department of Physics and Materials Science at the City University of Hong Kong, where he leads and promotes research on neutron scattering technology and material sciences. Prior to joining the City University of Hong Kong, Wang was the Group Leader and Distinguished Research Staff of the Neutron Scattering Science Division at the Oak Ridge National Laboratory in the United States, where he conducted research on kinetic control of microstructures and deformation behaviours at thermo-mechanical extremes.

Neutron scattering is a technique used by physicists and material scientists to study the mechanical and structural properties of matter. Conceptually, neutron scattering is similar to X-Ray diffraction in that researchers study the material of interest by emitting a stream of radiation at the object and evaluating its characteristics through the diffraction pattern of the radiation. However, neutron scattering has a few advantages over X-Ray. First, neutrons are highly penetrating because they do not interact with the material easily. In addition, it functions similarly at a wide temperature range and is not affected by magnetic fields. Therefore, researchers can use neutron scattering to study material properties in situ, that is, in a condition comparable to the material’s native environment, such as studying the structural properties of rocks under high pressure, a condition similar to that of the Earth’s inner crust; or the behaviour of a new metal alloy at extremely high temperatures inside a furnace, the condition that such material will be used in aerospace. Because of its importance and broad applicability, the pioneers of neutron scattering, Dr Clifford Shull and Dr Bertram Brockhouse, were awarded the Nobel Prize in Physics in 1994.

Critical to Neutron Scattering research is access to a high power neutron source, which requires state-of-the-art technology and long-term government investment to build one. Wang is one of the pioneers in this field, having spent 10 years building and overseeing the powder diffraction and neutron imaging instruments at both the Spallation Neutron Source and the High Flux Isotope Reactor, two premier neutron sources in the world, and spent 7 years leading the Neutron Scattering Science Division at the Oak Ridge National Laboratory in the United States.

More recently, neutron scattering research has proliferated in the Asia Pacific region, with heavy investments in powerful neutron sources in Japan, Korea, Australia, and China. Wang is particularly involved in the development of the China Spallation Neutron Source in Dongguan, Guangdong Province, in particular to help resolve technical issues and train technical staff to operate the facility.

Apart from research, Wang has also been played a critical role in educating and promoting neutron scattering technology in Hong Kong. With the support from Croucher Foundation, Wang has organised an annual summer school on neutron scattering since 2014, attracting some of the best students in the field from Hong Kong, China, India, Australia, and the United States. “It is a rare opportunity for the students to interact day-in, day-out with some of the best scientists in the world for 3 whole days, and the students have benefited tremendously.” Wang said. Riding on the success of the summer school, Wang decided to apply for funding to hold the world-renowned Gordon Conference in Hong Kong, the first in the neutron scattering community. Both the summer school and Gordon Conference have helped promoted neutron scattering to students and researchers in the Asia Pacific regions and encouraged collaborations between local researchers and leading scholars from around the world.

With the availability of new facilities and resources, Wang predicts that neutron scattering is going to be an important tool for material sciences, and at least one of the breakthroughs to come within the next 30 years will be traced back to discoveries made using neutron scattering. Given the heavy investment from the Chinese Government in this field, it is likely that such breakthrough will happen in China. “The question is how the research community in Hong Kong can take advantage of this unique opportunity.” Wang said. “By locating the facility in Dongguan, the government clearly wants to transform the Guangdong region from being a low-cost producer to a high-tech manufacturer. The entire region is going to benefit from this push, but how about Hong Kong?”

Professor Xun Li Wang is the Chair Professor and Head of the Department of Physics and Materials Science at the City University of Hong Kong and Adjunct Professor of the Department of Material Science and Engineering at the University of Tennessee. Wang has received numerous awards and honours in neutron scattering research, including the Fellow in the American Physical Society and the Outstanding Oversea Scholars from the Chinese Academy of Sciences. He obtained his Bachelor in Physics at the Peking University and PhD in Solid State Physics at the Iowa State University.

For more information on the Neutron Scattering summer course, please click here.