Mo

D-line Notes: MedOptics Dectector

Detlef Smilgies, CHESS

INDEX

start-up

cabling

shut-down

tricks & traps


calibration

About once a year the MedOptics detector should be recalibrated. This involves the following corrections:
In both cases the MacCHESS x-ray generator needs to be set up in the D1 hutch (Bill Miller).

The flat field correction accounts for variation in detector sensitivity, which arise over time and usage, as the fluorescent screen and the CCD chip age. Typically 4 images with an average intensity of about 10,000 counts average should be merged after background subtraction. Using the TVX program of the Gruner group the images can be processed to yield the new flatfield image of the detector. See TVX manual, pages 20-21.

For the distortion correction a hole mask pattern of 1 mm spacing is imaged onto the detector. Again, TVX can be used to evaluate the intensity pattern and generate the new correction files that will be used for the dark and corr commands.

If binning other than 1x1 is to be used, the same steps for flatfield and distortion have to be repeated. Typically 2x2 and 4x4 binning are the most useful, for increasing read-out spead and/or providing more averaging and higher S/N for diffuse scatterers, where the full resolution is not needed.

The current correction files are kept in directory ... on the station computer and a dated back-up should be made of each set.

set-up of the x-ray generator

The x-ray generator is set up by Bill Miller. The set-up will be insprected by the Safety Group - most important thing is that the x-ray generator does not poit towards the hutch door. Bill will provide training to the x-ray generator operator. SOP's are listed in the blue folder.