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 in vestigated with neutron scattering. For basic structural studies and t he determination of bulk moduli, a simple attenuation correction is su fficient in most cases. For more detailed or precise structural studie s, such as obtaining realistic temperature factors at high pressures, a much more accurate evaluation of the attenuation correction is requi red. The incident and diffracted neutron beams travel through the anvi ls, sample, and the gasket, and so the correction has to take into acc ount both the variation of the attenuation of each material with neutr on energy and the differing pathlengths through a variety of materials taken by each ray. A program is currently being developed which can c arry out the attenuation corrections for any shape definable by a coll ection of quadric surfaces. This geometric flexibility also allows us to carry out design improvements on the geometry and shielding of the anvils.