User_Manual-PILATUS-V1_2.doc 37/57
Vtrm scan
Set all trimbits to high and increase Vtrm until all pixels are counting less than
half of the value at trim=0; generally almost all pixels will be off at this point.
Keep this value.
Trimbit scan
With these values, record images for every trim setting from 0 to 63. The
result is a calibration curve for every single pixel. The trimbits are set to the
value of the inflection point of this curve.
10.2 Calibrating the detector manually
As every detector is calibrated at least with 3 different energy levels
before it leaves the factory, normally there is usually no need to create new
trim files.
But in case you require a different setting at a special energy, you can trim the
detector yourself.
The detector is irradiated with uniform x-ray illumination with a defined energy,
the calibration is done and the result is stored in a trim file. For different
energy levels and preamplifier setting, different trim files have to be created.
Once a trim file is created, it can be loaded for the appropriate x-ray energy to
achieve a uniform measurement.
All the glossaries and subroutines are in the directory:
config/trim_gls
To simplify the calibration, the script p2_trim_det.gl guides you
through the whole calibration process for 1 energy.
Depending on the flux of the x-ray source this calibration may take
several hours.
The first step is to create a good pixel mask for the use in the statistical
comparisons. In the tvx window type get “trim_gls/p2_make_mask.gl”.
Then to create a trim file for a detector module you should run the following
command in the TVX window: get “trim_gls/p2_trim_det.gl” (the quotation
marks are required).
You will be prompted to enter a name for the directory in which the trim files
will be stored; this should be a directory that does not already exist. A format
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