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makesensi: create detector response map

The "makesensi" program can measure the detector response map using a fluorescent sample.

Usage

The program is invoked by the command line:

  makesensi [options] [make]

Without the "make" argument, the program interprets existing images "ffdark.kcd" and "flatfield.kcd". With "make" argument, these two images are first created. Based on the actual performance of the machine, an appropriate integration time is calculated. For a 65mm KappaCCD on a sealed tube this will normally amount to 2x3 hours.

When the program is run with the "make" argument, it will give instructions on sample mounting and alignment. It will then check the sample, and go on with the measurement if all is OK.

The Fluorescent samples: Left on each picture the Fe sample for calibrating Cu radiation sensitivity, at the right the Y2O3 sample for calibrating Mo and Ag radiation sensitivity.

The Fluorescent sample in place. To check the alignment start the "makesensi make" procedure, and when the program asks to mount the sample, look along the beamstop blade into the collimator. Exactly half of the collimator hole should be visible.

If the program is not happy with the results of the preliminary scans, it will abort with a message "Sample is too far from the detector" or "Sample is too close to the detector". In such a case, restart the program, and move the sample a little bit on the goniometer head towards or away from the detector depending on the message. Iterate this until the program is happy about the sample alignment. The criterion is that there should be less than 0.5% difference in intensity between the left and right sides of the detector ("Ratio of ratios" should be between 0.997 and 1.003).

The program chooses the exposure time per frame and the number of frames based on a few test exposures it makes at the start. These values can be overwritten by the command line options "repeat=n" and "frametime=f" (n is the number of times the image should be measured, and f should be the exposure time per frame in seconds).

The final output is produced in the form of a KCD file: responsMO.kcd for a MoKa machine, and responsCU.kcd for a CuKa machine. This file should be copied to the calibration directory (usually /usr/local/calibration/<detid>)

If the output file responsXX.kcd exists and is more recent than the existing ffdark.kcd and flatfield.kcd, the calculations are skipped. The "force" option exists to force a recalculation in such a case.

If the additional option "transmission" is given on the command line, two transmission flood-field measurements will also be performed for backward compatibility.

If the optional argument "askstop" is given on the command line, the program will ask for confirmation before giving up if it thinks the sample is not properly positioned.

For non-standard samples, there is another option "misalign". This represents the phi-misalignment of the fluorescent platelet. Do not use this option for standard samples, as these can be better aligned by hand; this option was designed for experimental samples used in the factory at some point.

Notes

It should not be necessary to re-measure the detector sensitivity once it has been established, unless a new (improved) calibration procedure is established.
A proper detector alignment is essential for calibration. "dx" must be accurately set before measuring the fluorescent sample. Make sure to run caldx, caltheta, and makedetalign before even thinking about running "makesensi".
Do not run the fluorescent sample in open beam mode. The fluorescent sample when irradiated radiates in all directions, so you can not assume a safe position with the radiation safety enclosure open. Furthermore, the alignment of the sample requires you to take a dangerous position in front of the primary beam, so it must be impossible to open the shutter during that step.

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Next: spoton: Follow a reflection over the detector