[continues from 4.6.1]
The top fraction of the scintillation region contributes also to the total
efficiency; events that interact in this top region produce a
BL within the nominal thresholds. This effect can be modelled by a "fudged"
layer of Xenon, whose depth is stored in files
m{1,2,3}_scintillation.coeff
The values are:
- the depth of the M1 active scintillation region : ==> mm
- the depth of the M2 active scintillation region : ==> mm
- the depth of the M3 active scintillation region : ==> mm
- the Xe density (at 273 °K) : /poseidon/lucio/xas/calib/sax/mecs/m1_scintillation.coeff g/cm3
Fig. 4.6.2-I : absorption efficiency in the scintillation region
The overall efficiency of the gas cell is the sum of the
absorption efficiency in the
drift region and of the product of the
absorption efficiency in the scintillation region (see
figure above) times the transmission efficiency
of the drift region (complement to 1 of the relevant absorption).
Fig. 4.6.2-II : overall efficiency of the MECS gas cells