Principle of the system is based on use collimated X-ray beam by thin lead slit, which can be sent on to detector at a sharp angle. Pointing such beam to particular detector position we can determine the depth of interaction for each pixel along the beam path. Shifting the detector along the axis perpendicular to the plane of the beam (hitting other columns) we can obtain a 3D map of the detector response.
Precise positioning of the slit and detector is essential. The system has seven degrees of freedom: detector position, rotation and tilt, slit position and width and global shift and rotation of the whole platform (with respect to the X-ray tube). The slit collimator consists of pair of flat lead plates with total thickness of 14 mm. The slit width is controlled by motorized stage with precision of 1 µm.
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