Gain Correction Factors

Definition

• The gain correction factor is defined for images averaged over 100 events for good pixels as
  g(i,j) = <Amplitude in ASIC> / Amplitude(i,j),
  where i and j are the pixel indexes in ASIC.
• The gain correction factor is set to "0" for bad pixels.

The gain correction factors for runs 901, 902, and low gain 903, 904, 905, and 906

with transmission 0.002, 0.005, 0.005, 0.1, 0.5, 1, respectively

Gain correction factor distribution over quad-2 pixels in different runs

Amplitude spectra with (and without) corrected gain

Run 901, trans.=0.002

• Spectrum is shown for events 1,11,21,31, and 41, respectively.
• The bad pixels are discarded from these spectra.

Spectra for all good pixels

Spectra for pixels from central region 48<iy<146 of [0-194] range (WITHOUT GAIN CORRECTION)

Spectra for pixels from two side regions iy<49 and iy>145 of [0-194] range (WITHOUT GAIN CORRECTION)

Run 902, trans.=0.005

• Spectrum is shown for events 1,11,21,31, and 41, respectively.
• The bad pixels are discarded from these spectra.

Spectra for all good pixels

Spectra for pixels from central region 48<iy<146 of [0-194] range (WITHOUT GAIN CORRECTION)

Spectra for pixels from two side regions iy<49 and iy>145 of [0-194] range (WITHOUT GAIN CORRECTION)

Run 900, trans.=0.02

• Spectrum is shown for events 1,11,21,31, and 41, respectively.
• Fit is not applied because peaks are not distinguished

Spectra WITH gain correction:

Spectra WITHOUT gain correction:

Spectra for pixels from central region 48<iy<146 of [0-194] range (WITHOUT GAIN CORRECTION)

Conclusion

• Gain factors have the RMS spread ~5-10% depending on high/low-gain mode and intensity of illumination.
• There is no significant improvements of the amplitude spectrum after the gain correction is applied.
  • Comparison of spectra of pixels from central region and side bands shows that resolution is significantly better in central region.
  • The gain correction is small comparing to the amplitude spread due to resolution, especially for side bands.
• In run 900 (with a large transmission = 0.02, nu=2) the 0-,1-,2-photon peaks are not resolved even for central band both WITH and WITHOUT gain correction.