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F.3 Gain Saturation Correction (GSC)

At large charge input (high energy photons as well as high count rate) some saturation of the gain is arising in the PSPC. The fall-off in the signal amplification as a function of event amplitude has been modeled using spectral calibration data (cf. Eq. (F.6)) . At present the rate gain effect is not taken into account.

The offset values tex2html_wrap_inline18401 for tex2html_wrap_inline18403 135, 146, and 103 are tex2html_wrap_inline18405 89.2, 96.1, and 69.1, respectively. Below these values thresholds gain saturation is negligible.

According to Chap. 3 the rate gain effect can be understood in terms of pseudo-continuous presence of a substantial electron cloud causing a reduction in the electronic field. Measurements at the PANTER test facility have shown a drop of the gain of 1% at E = 1.487keV and 2% at E = 3keV for an X-ray count rate of 500s tex2html_wrap_inline18411 . Further investigations were planned.

Figure F.3 shows the PHA channel difference between the non-linearity and gain saturation correction.

Figure F.3: Difference between the channels after gain saturation correction ( tex2html_wrap_inline18413 ) and after non-linearity correction ( tex2html_wrap_inline18415 ) as function of tex2html_wrap_inline18417 according to Eq. (F.6). The correction effect is shown for three typical gain values ( tex2html_wrap_inline18419 , 135, 146).



SASS source code: package PSPC, bubble CT, subroutine CGS

SASS files: none

Figure F.4: The temporal gain correction factor tex2html_wrap_inline18429 according to Eq.(F.7) as function of the gain (expressed in terms of the Al K tex2html_wrap_inline18431 line bin tex2html_wrap_inline18433 ). It is tex2html_wrap_inline18435 , tex2html_wrap_inline18437 , and tex2html_wrap_inline18439 .

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