CRYOSTAT FOR SYNCHROTRON POWDER DIFFRACTION WITH SAMPLE ROTATION AND CONTROLLED GAS ATMOSPHERE IN THE SAMPLE CHAMBER

The cryostat for 8 < T < 300 K presented here, based on a closed-cycle cryogenic engine, optimizes the powder-grain statistics of the sample by the use of a cold sample spinner working within an open helium-gas atmosphere for thermal contact. The compact design of the cooling stage adapted to the Bragg-Brentano-type diffraction geometry provides for a large open interval, 0 < 2THETA < 180-degrees, of diffraction angles. A wide variety of sample holders allows measurements with plane powder samples and thin films at low temperatures under variable orientation.