Fixed pattern deviations in Si pixel detectors measured using the Medipix1 readout chip

Dopant fluctuations and other defects in silicon wafers can lead to systematic errors in several parameters in particle or single-photon detection. In imaging applications non-uniformities in sensors or readout give rise to fixed pattern image noise and degradation of achievable spatial resolution for a given flux. High granularity pixel detectors offer the possibility to investigate local properties of the detector material on a microscopic scale. In this paper, we study fixed pattern detection fluctuations and detector inhomogeneities using the Medipix1 readout chip. Low-frequency fixed pattern signal deviations due to dopant inhomogeneities can be separated from high-frequency deviations.