[continues from 4.3]

4.4 Calibration source parameters

The reference characteristics of the calibration sources are stored in files m{1,2,3}_calsource.coeff and are used by the gain history accumulation program. These characteristics are :

4.5 Beryllium window transmission

The term tauw is the transmission of the Be window at a given energy and position, reported in fig. 4.5-I. Its dependencies are:

Fig. 4.5-I : Transmission of a Be layer with nominal thicknesses
of the MECS entrance window (solid) and its supporting strongback (dotted).
The dashed black line is the overall transmission in a point
at x,y = (0,5) mm, i.e. on the edge of the strongback.

Namely, the transmission at one given position x,y is computed combining the transparencies of the two thicknesses twindow and tstrongback

    tauw = Z(E,x,y) exp (-mu(E)twindow) + (1-Z(E,x,y) exp (-mu(E)tstrongback) 
where Z(E,x,y) is the convolution of a 1/0 mask representing the Be entrance window with the optics PSF (i.e. the coverage fraction of the window) and its complement 1-Z is the coverage fraction of the strongback.

Additional representations (as separately numbered figures) can be obtained via the following form. Please note that the time needed to compute images can be prohibitively long (more than 10 minutes) and CPU-intensive : please reserve this option to off-peak hours.

Plot/compute ONE of the following parameters for MECS unit
Item and/or quantitySymbolSelect
Overall transmission tauw
Be window layer tauwindow or Zwindow
strongback taustrongback or Zstrongback
Be window layer, product Zwindow*tauwindow
strongback, product Zstrongback*taustrongback

select ONE type of data representation, the relevant parameter and data format
transmission tau vs E none
v(E) at given position x,y mm
v(x,y) image at E (SLOW!) keV

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