[continues from 4.10.1]

4.10.2Positional dependency

The gain of the detector is not uniform across the detector surface. This dependency is essentially due to disuniformities in the PMT and is strictly independent of energy.

Maps of the relative gain vs unlinearized position have been determined on the ground measuring the position of reference lines at different positions using a multipinhole mask. Since there is no dependency on energy, all maps have been averaged, allowing to determine the relative gain with an uncertainty of 0.3 % in the central part of the field of view (the uncertainty is higher close to the calibration sources, because of lack of close multipinhole measurements).

The relative gain maps are kept in XAS image form in (binary) files m{1,2,3}_gain.image. Access and display of such data (as separately numbered figures) is possible via the following form:

Unit :
Data :

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