The position resolution of channels 1 and 2 are approximately 350 m, and channels 3 and 4 somewhat larger.
The wedge-and-wedge pattern of the detector can be stimulated through a set of three pads located on the rear of the quartz plate. When a signal is applied to a pad, it induces a charge on the pattern in the same way that an incoming photon would, but at a known location. During a stim test, each pad is stimulated in turn. The position resolution and linearity of the detectors are regularly measured using these electronic stims.