A Diamond Anvil Cell Facility at the Advanced Photon Source. Guoyin Shen, Thomas Duffy^*, Mark Rivers, Peter Eng, Stephen Sutton, and Yanbin Wang Consortium for Advanced Radiation Sources, The Univ of Chicago, Chicago, IL 60637, ^*Department of Geosciences, Princeton University, Princeton, NJ 08544

Ultrahigh pressures and temperatures in the diamond anvil cell are achieved at the expense of reducing sample volume. Characterization capa-bility with high spatial resolution is most fundamental for probing microscopic samples at high pressure and temperature and for minimizing the effect of gradients. Measurements using X-ray techniques require the highest possible X-ray brilliance, and it is thus evident that high brilliance synchrotron radiation sources such as the Advanced Photon Source (APS, a new third generation synchrotron) are ideal for ultrafine and sensitive X-ray measurements. The diamond anvil cell (DAC) program is an important part of high pressure experimental programs at GSECARS. The scientific goal of the program is to study properties of materials across the entire pressure-temperature spectrum of the terrestrial planets by a variety of high pressure experiments, including single crystal and polycrystalline X-ray diffraction, deviatoric strain measurements, diffraction at simultaneous high pressures and high temperatures, high resolution X-ray diffraction, hydrothermal reaction measurements, measurements of liquid and glass structures, and X-ray Raman and inelastic scattering. Technically, the goal is to significantly extend the range (e.g. pressure and temperature) of feasible high pressure experiments. At the same time, there is a major effort to improve the accuracy of the experimentally determined quantities.

An energy dispersive diffractometer for diamond cell experiments has been constructed. In addition to the two circle diffractometer, a multi-axis diffractometer is available for DAC diffraction. To accommodate the restricted scattering geometry imposed by diamond anvil cells, this diffractometer has two additional degrees of freedom compared to a classic Kappa diffractometer. The geometry is referred to as 2+2+Kappa. Laser heating of diamond-cell samples provides the means of creating static high P-T conditions. A double sided laser heating system is being developed with the X-ray diffractometer.