Probing past and future materials with neutrons
Box 2 | The development of neutron beam science
In 2002 the Bragg Institute was set up to foster links between academic and commercial research organisations within Australia and overseas. Researchers apply their expertise in the use of neutron beams to a wide range of fields including plastics, minerals, engineering, pharmaceuticals, electronics and biology.
The Institute was named in honour of the father and son team of William and Lawrence Bragg. They were awarded Australia's first Nobel Prize in Physics in 1915 for their work on the analysis of crystal structure using X-ray diffraction. This involves firing X-rays through the crystal lattice of a material. The atoms in the lattice cause the X-rays to scatter and by measuring the pattern of the emerging X-rays – the diffraction pattern – it's possible to calculate the arrangement of the atoms in the material. The Braggs first used X-ray diffraction patterns to determine the crystal structure of common salt, sodium chloride.
Of course, neutron diffraction wasn't available in 1915. Indeed, neutrons hadn't even been discovered. That didn't happen until 1932 when British physicist James Chadwick proved the existence of sub atomic particles found in the nucleus of the atom that were devoid of any electrical charge – neutrons. This discovery earned Chadwick a Nobel Prize in 1935.
The value of this new particle in probing the nature of matter didn't become clear until after 1945 with the development of nuclear reactors and the availability of usable amounts of neutrons, one of the products of nuclear fission. In 1946 the first neutron diffraction experiments were carried out and the field of neutron scattering developed over the following decades.
In recent years neutrons have been used increasingly to study the structure and movement of molecules in solids and fluids. Neutron scattering techniques are used in such widely differing areas as the study of the new ceramic superconductors, catalytic exhaust cleaning, elastic properties of polymers and virus structure.
Boxes
Box 1. Analysing the old and new
Box 3. Access for all
Related sites
The Nobel prize in physics 1915
(Nobelprize.org, Sweden)
The Nobel prize in physics 1935: Presentation speech
(Nobelprize.org, Sweden)
Bragg scattering (Israel Institute of Technology, Department of Physics)
Posted March 2007.