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Optical measurement

Optical measurement is maintained by Chris Kenney. Detector or its quad is installed on microscope table and 3-d coordinates of all 2x1 sensor corners are measured with precision about 8um (RMS) in x-y plane. All corners in the measurement are numerated in arbitrary order. It is expected that numeration order should be the same for different measurements. This procedure depends on CSPAD construction;

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The official place for CSPad alignment parameters is
/reg/d/psdm/<INSTRUMENT>/<experiment>/calib/CsPad::Calib<VERSION>/<CSPad-name>/<type>/<run-range>.data
The file name consists of the run range followed by the .data, for example, 0-end.data, 11-end.data, 47-52.data, etc.

All CSPAD geometry alignment parameters are splitted split for 9 types:

• center - x, y, z center position of each 2x1 for all quadrants. Comes from optical measurement.
• center_corr - additional manual correction to the center parameter. Can be applied if the optical measurement has (non-)obvious problems.
• marg_gap_shift - margins, gaps, and shifts between quads, as explained below. Comes from image-based tuning.
• offset - x, y, z coordinates for 4 quads. Fairly-reasonable assigned before tuning of the offset_corr and marg_gap_shift parameters.
• offset_corr - additional correction to the offset. Comes from image-based tuning.
• quad_rotation - 4 quad rotation in n*90 degree. Comes from basic geometry.
• quad_tilt - 4 quad tilt in fractional degree. Has never been used. In latest optical measurement is accounted through the global 2x1 coordinate measurement in the detector.
• rotation - 8 2x1-rotation angle for 4 quads in n*90 degree. Comes from basic geometry.
• tilt- 8 2x1-tilt angle for 4 quads in fractional degree. Comes from optical measurement.

All coordinates are defined in size of pixel, which is 109.92 x 109.92um (and 274.80 x 109.92um for two rows between two of 2x1 ASICs.) The quadrant size is pre-defined as 850x850. The marginesmargins, shifts and gaps are defined for these quads. The offset and offset_corr are defined for low-left angle of the rotated by n*90 degree quad. Size of entire CSPad image does not matter for this alignment.

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