[continues from 4.5]
The term epsilon is made of two terms corresponding to the
two regions of the detector: the
drift region where the bulk of the conversion of X-rays
into electrons occur, and the scintillation region,
where residual conversion of some X-rays may occur.
In both cases the energy dependency is modelled through the Xe
absorption cross section (computed from atomic coefficients hardcoded
in the programs).
The calibration parameters of the drift region in the cell are currently
the same for all three MECS units.
The values of these parameters for all three
MECS units are stored in file
cell.coeff
and are:
- the depth of the drift region : ==> mm
- the Xe density (at 273 °K) : /poseidon/lucio/xas/calib/sax/mecs/cell.coeff g/cm3
Fig. 4.6.1-I : absorption efficiency in the drift region
(click on figure to expand Y scale)