BROCKHOUSE , BERTRAM NEVILLE

Brockhouse gained his PhD from the University of Toronto in 1950. He worked initially with the Atomic Energy Commission of Canada at the Chalk River Nuclear Laboratory, Ontario. In 1962 he moved to MacMaster University, Hamilton, Ontario, where he remained until his retirement in 1984.

The construction of nuclear reactors in Canada and the USA in the 1940s allowed physicists, once the war had ended, to use neutron beams to explore atomic structure. Neutrons are more effective probes than protons because they are electrically neutral and consequently do not interact with the orbiting electrons. As neutrons can behave as waves they produce diffraction patterns as a result of collisions with their target atomic nuclei. The effect is similar to that of x-ray diffraction, in which the crystal lattice acts as a diffraction grating for the particles. Neutron diffraction from crystals can be used to select beams of neutrons with the same energy. These ‘monochromatic’ beams can then be used in neutron-scattering experiments.

Brockhouse chose to study the inelastic scattering of neutrons as they bombarded atoms bound in a crystal lattice. In this procedure neutrons give up or gain energy from the atoms they collide with. Monochromatic neutron beams were directed at a crystal target and the energies of the scattered neutrons measured as they emerged. It was thus possible to determine how much energy had been gained or lost. With this data Brockhouse was able to obtain information about the vibration of atoms in the crystal and such important properties as its ability to conduct heat and electricity.

For his work on atomic structure Brockhouse shared the 1994 Nobel Prize for physics with Clifford Shull.