Multichannel detector-collimator for powder diffraction measurements at energy scanning x-ray absorption spectroscopy synchrotron radiation beamlines for high-pressure and high-temperature applications

We describe a modular detector system suitable to intercept the diffracted x-ray radiation (Debye-Scherrer rings) in a transmission geometry setup at monochromatic tunable synchrotron radiation beamlines. The detector consists of several independent channels composed of a motorized front slit and a rear detector slit system which can be mounted in either a vertical or a horizontal configuration. The detectors are placed at fixed scattering angles 2theta and the diffraction scan is performed by tuning the monochromator energy. The availability of a multidetector system allows one to cover a wide range of scattering vectors with limited range energy scans. The photon sensitive elements are based on CdZnTe solid state detectors which are used at ambient temperature for high efficiency photon counting in the 10-60 keV range. In alternative, conventional NaI(Tl) scintillation detectors can be integrated in the setup. The system can be mounted in a high-resolution configuration and typical widths in the range DeltaE/Esimilar or equal to10(-3) have been obtained for Bragg peaks. In these conditions the sensitivity to changes in the lattice spacing is better than 10(-4). This detector system fully complements the experimental devices usually available at x-ray absorption spectroscopy beamlines and the short range structural information obtained using the x-ray absorption fine structure technique. Typical applications include high-pressure and high-temperature investigations of condensed matter. (C) 2003 American Institute of Physics.