The MAMA detector begins to experience nonlinearity (photon impact rate not equal to photon count rate) at global (across the entire detector) count rates of 200,000 counts/second. The nonlinearity reaches 10% at 360,000 counts/second and can be corrected for in post-observation data processing at the price of a loss of photometric reliability. Additionally, the MAMA detector plus processing software are not able to count reliably at rates exceeding 285,000 counts/second. For this reason, and to protect the detectors, observations beyond this rate are not allowed (see Section 4.6).
The MAMA detector remains linear to better than 1% up to ~22 counts/second/pixel. At higher rates, it experiences local (at a given pixel) nonlinearity. The nonlinearity effect is image dependent-that is, the nonlinearity observed at a given pixel depends on the photon rate affecting neighboring pixels. This property makes it impossible to correct reliably for the local nonlinearity in post-observation data processing. In addition, MAMA detectors are subject to damage at high local count rates (see Section 4.6).
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