ATTENUATION CORRECTIONS FOR THE PARIS-EDINBURGH CELL

The success of the Paris-Edinburgh cell in routinely reaching 10 GPa (and more recently 25 GPa during development work) means that the high-pressure physics of structures containing low-Z elements can now be investigated with neutron scattering. For basic structural studies and the determination of bulk moduli, a simple attenuation correction is sufficient in most cases. For more detailed or precise structural studies, such as obtaining realistic temperature factors at high pressures, a much more accurate evaluation of the attenuation correction is required. The incident and diffracted neutron beams travel through the anvils, sample, and the gasket, and so the correction has to take into account both the variation of the attenuation of each material with neutron energy and the differing pathlengths through a variety of materials taken by each ray. A program is currently being developed which can carry out the attenuation corrections for any shape definable by a collection of quadric surfaces. This geometric flexibility also allows us to carry out design improvements on the geometry and shielding of the anvils.