Radiation damage effects CCD detectors Marcel Dobber (KNMI) Quintus Kleipool (KNMI)
Radiation damage effects CCD detectors OMI on NASA’s EOS-Aura (launched 15 July 2004) 2 CCD detectors CCD EEV 55 576 rows and 780 columns additional read-out register with 814 columns GOMOS on ESA’s ENVISAT (launched 1 March 2002) 4 CCD detectors CCD EEV 2610 with 2*143 rows and 1353 columns OSIRIS on ODIN (launched 20 February 2001) CCD EEV model CCD 26 1353 x 286 elements
CCD detectors GOMOS OMI
OMI aluminium shielding 10 kg additional aluminium shielding average thickness 29 mm no additional shielding for GOMOS and OSIRIS
Trapped proton radiation damage Damage caused by high energetic protons (> 10 MeV) trapped in the magnetic field of the earth.
Analysis Estimate number of hit pixels by: counting permanent spikes with permanently increased dark current. works well if unbinned dark spectra are available (OMI and OSIRIS), not for GOMOS. calculate normalised time-difference histograms works well for both unbinned (OMI, OSIRIS) and binned cases (OMI, GOMOS).
Analysis OMI histogram time difference
OMI, binning factor 7, histogram time difference.
OMI count unbinned hot pixels.
Analysis GOMOS histogram time difference.
OSIRIS count unbinned hot pixels.
OSIRIS histogram time difference method.
Conclusions sofar Different time periods vs solar cycle. OMI on-ground testing almost 100% damaged, hence > Shielding high- and low-energetic protons vs secondaries (neutrons). Counted hot pixels, assessment of impact on hot pixels (increase dark current, RTS, etc.) is much more difficult.