Page History

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Selection of algorithm of particular type is controlled by the parameters in file for common_mode calibration type.

#1 - common mode peak finding algorithm

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Valid for: CsPad and CsPad2x2

This algorithm is similar to one developed by Andy Salnikov and implemented in cspad_mod.CsPadCalib;

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• par[4] - number of segments for common mode evaluation
• par[5] - segment size (number of pixels for common mode evaluation)

• par[6] - stride (step for jump to the next pixel)

  For example:

  Code Block
  1 50 50 100 8192 128 1

#2 - MEAN algorithm

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Not valid for

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: CsPad and CsPad2x2

It was developed by Philip Hart for test purpose;

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• par[0] - algorithm #
• par[1] - maximal threshold on intensity to evaluate mean for low intensities
• par[2] - maximal allowed common mode correction

• par[3] - length of consecutive pixel array for common mode evaluation
  For example, for pnCCD one can evaluate common-mode for one came chip (128 channels).

  Control file:   /reg/d/psdm/amo/<exp-name>/calib/PNCCD::CalibV1/Camp.0:pnCCD.0/calib/PNCCD::CalibV1/Camp.0:pnCCD.0/common_mode/0-end.data

  Code Block
  2 1000 1000 128

• The algorithm loops over the data and evaluates consecutive arrays of specified length (which might represent for example a row of pixels in a readout chip) and finds the mean value for values below a threshold, ignoring masked pixels.  It corrects all the data if the calculated common mode is less than the maximal allowed correction.  The median algorithm is more stable in many cases and is recommended.

#3 - MEDIAN algorithm

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Not valid for: CsPad and CsPad2x2

It was developed by Philip Hart as a replacement for the mean (#2) algorithm;

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Parameters are the same as in #2.  The algorithm is as above, except that it calculates the median, or the average of the two median points if there are an even number passing the selection criteria.

Code Block
3 100 100 128

#4 - MEDIAN algorithm - detector dependent

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Not valid for

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: CsPad and CsPad2x2

It is pretty similar to one developed by Matthew Weaver that is implemented in ami/event/FrameCalib

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Other parameters are not used.

#5 - Unbond pixels common mode correction

Only valid for

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: CsPad and

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CsPad2x2

In latest version of CSPAD (including 2x2) detectors a group of pixels is not bound to relevant electronic channels. Signal from these channels can be used to evaluate common mode variation of the sensor. Typical common_mode  control parameters:

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