High-Pressure Neutron Diffraction

Neutron diffraction is the only technique able to ``see'' hydrogen and other important light elements. It is the ideal method to study a wide range of important and common materials like ice and ammonia. Knowledge of the positions of the atoms in systems like these when they are compressed helps our understanding of topics as diverse as the behaviour of proteins and the origins of the magnetic fields of planets like Uranus and Neptune.

 Crambin – a protein 

Uranus – a gas giant planet


Until 1990, neutron diffraction was limited to pressures below 30,000 atmospheres. This was a very low pressure when compared to other structural techniques like x-ray diffraction  and light-scattering  which at that time were achieving pressures in excess of 1 million atmospheres. Over the past ten years a collaboration between the Edinburgh group and the group at Physique des Milieux Condensés, Université Pierre et Marie Curie in Paris has increased the pressure range for neutron diffraction by a factor of ten with the development of a novel large volume pressure cell — The Paris Edinburgh cell.

Paris Edinburgh cell

The Paris-Edinburgh cell

The cell is designed for use at the United Kingdom's pulsed neutron source, the ISIS facility, at the Rutherford Appleton Laboratory near Oxford. A recent grant to the University of Edinburgh from the Engineering and Physical Sciences Research Council has enabled the construction of a dedicated set-up for high pressure, HiPr on the PEARL beamline.

HiPr – the high-pressure diffractometer on the PEARL beamline

Our science programme includes studies of fundamental  ices like ice, ammonia, methane and hydrogen sulphide; hydrogen-bonded solids like sodium , potassium  and cobalt hydroxides; novel electronic materials like boron carbide. Most recently we  have started a programme of study of molecular mixtures including studies of  ammonia and methane hydrates.

Our group consists of Richard Nelmes, John Lovedayand Malcolm Guthrie from Edinburgh who are all based at Rutherford Appleton Laboratory and Michel Besson, Stefan Klotz and Gerard Hamel in Paris.
Edinburgh People
Richard Nelmes
John Loveday

Paris People
Stefan Klotz
Gerard Hamel