The purpose of the project was to provide the users (crystallographers, chemists, physicists, mineralogists) with a 4-circle diffractometer allowing an easy, fast and precise data collection on single crystals in different sample environments. The instrument specially built for the beamline has resulted from the association of two companies each well known in their area: Newport (Microcontrol) for the goniometer part and Agilent (Oxford Diffraction) for the detector and data analysis software.
The data are measured using the oscillation method: for each image acquisition, the diffraction signal is measured while the sample is rotated at constant speed over a small angular range (typically 1°). Therefore, the requested main characteristics of this instrument are:
a 2D CCD detector permanently mounted, which can be translated (80 mm < dtx < 340 mm)
high accuracy of motions,
very small sphere of confusion to be able to study micro-crystals (Ø < 10 µm),
data acquisition/analysis software package standard and familiar to most users.
All the motors are DC motors driven with Newport XPS controllers. Let us recall that the Cylinder of Confusion (CoC) is the largest diameter of the cylinder described by the sample during the motion of the concerned rotation axis, and the Sphere of Confusion (SoC) the largest dimension of the volume described by the sample during the motion of all the axes.