Six-circle diffractometer with atmosphere- and temperature-controlled sample stage and area and line detectors for use in the G2 experimental station at CHESS

A new diffractometer system was designed and built for the G2 experimental station at the Cornell High Energy Synchrotron Source (CHESS). A six-circle kappa goniometer, which provides better access to reciprocal space compared to Eulerian cradles, was chosen primarily to perform large angle Bragg diffraction on samples with preferred crystallographic orientations, and can access both horizontal and vertical diffraction planes. A new atmosphere- and temperature-controlled sample stage was designed for thin film thermomechanical experiments. The stage can be operated in ultrahigh vacuum and uses a Be dome x-ray window to provide access to all scattering vectors above a sample's horizon. A novel design minimizes sample displacements during thermal cycling to less than 160 mu m over 900 degrees C and the stage is motorized for easy height adjustments, which can be used to compensate for displacements from thermal expansion. A new area detector was built and a new line detector was purchased. Both detectors cover a large region in reciprocal space, providing the ability to measure time-resolved phenomena. A detailed description of the design and technical characteristics is given. Some capabilities of the diffractometer system are illustrated by a strain analysis on a thin metal film and characterization of organic thin films with grazing incidence diffraction. The G2 experimental station, as part of CHESS, is a national user facility and is available to external users by application.