Page History

...

Tile center coordinates are defined as an average over 4 corners. Tilt angles are projected angles of the tile sides on relevant planes. Each angle is evaluated as an averaged angle for 2 sides.

Origin of the detector local frame is arbitrary. There are few preferable options for choosing coordinate frame origin:For example, for CSPAD with moving quads it is convenient to define

• 2x1 sensors' center coordinates in the quad use the same coordinate system as in optical measurements,
• apply minimal offset (translation) to optical frame in order to make all coordinates positive (see left plot below),
• use averaged coordinate of all tiles (see right plot below),
• use user-defined translation, for example set origin in the evaluated quad origins' coordinates with respect to the point of beam crossing with the detector plane. , as shown on plots:
       Image Added                Image Added

               Image Removed                               Image Removed 

Pixel coordinates reconstruction

Pixel coordinate reconstruction in the detector frame uses

• tile ideal geometry,
• tile center positions,
• tile N·90 rotation and tilt angles.

Then, each Each geometry object pixel coordinate xj are transformed to the parent frame pixel coordinate Xi applying rotations and translations as
         Xi=Rij·xj + Pi,

...

Pixel coordinates in the detector should be accessed by a the method like

              xarr, yarr, zarr = get_pixel_coords().

For example, Python interface for CSPAD

...