Evolution of SPI detector count rates over the mission. The SPI anticoincidence system mainly records charged-particle interactions, thus creating a veto signal for the Ge detector electronics; this avoids full processing of Ge detector signals for events that are coincident with a cosmic-ray hit. Shown are measured rates of the anticoincidence system (blue, left axis), and two different event rates in the Ge detectors (green for total, red for non-vetoed and thus either delayed background or potentially celestial triggers; right-side axes). Sporadic high rates are caused by solar flares.