Space resolution of a silicon pixel detector as a function of the track angle

We measured the spatial resolution of a 300 μm thick 75 × 500 μm silicon pixel detector as a function of the track angle using a 120 GeV pion beam. We observed that 13% of tracks perpendicular to the detector give a signal on two neighboring pixels; this fraction increases to 50% at an angle of 15° w.r.t. the normal incidence direction. The average spatial resolution is 28.2 μm at 0° and 14.6 μm at 15°. The detector efficiency is not affected by the charge sharing between pixels. Our data agree with the predictions of a simple geometrical model describing the charge sharing in the region between pixels. This model can be the basis for a full simulation of the behaviour of a pixel detector.