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Pedestal Scans and Charge Injection

(from Conny on Jan. 24 2024)

As you mentioned, this detector only has one gain mode, which is an outranging mode. However, the idea is to create two additional “fixed gain modes” currently referred to as soft fixed modes. These modes are created by changing the switching point of the auto-ranging mode. So for the SL, the switching point is moved below the baseline and we are always switched, and for SH the switching point is all the way up the dynamic range, so the detector never switches.  As such, unlike the current generation of epix detectors which moves between gain modes by changing the tr_bit and the pixel config matrix value (ePixM do not contain registers that change the functionality of the pixels),  the soft gain modes will be moved into by changing the following registers:

Here the CompTH_ePixM register defines the location of the switching point. The values of these registers are subject to change as we start to characterize the detector and might change a bit when we optimize the performance. So, for a pedestal script, we would likely want to cycle through these settings and collect ~2000 frames in each cycle to determine their relative pedestal maps (AHL, SH,SM).

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