Quantitative Determination of Spatial Resolution and Linearity of Position-Sensitive LG-SiPMs at Sub-Millimeter Scale via Ricean Distribution Fitting

Position-sensitive SiPMs are useful in all light detection applications requiring a small number of readout channels while preserving the information about the incoming light’s interaction position. Focusing on a 2x2 array of LG-SiPMs covering an area of $\sim 15.5\times 15.5\mathrm{m}\mathrm{m}$ with just 6 readout channels, we proposed a quantitative method to evaluate image reconstruction performance. The method is based on a statistical approach to assess the device’s precision (spatial resolution) and accuracy (linearity) in reconstructing the light spot center of gravity. This evaluation is achieved through a Rice probability distribution function fitting. We obtained an average sensor spatial resolution’s best value of $81\pm 3\mu \mathrm{m}$ (standard deviation), which is achieved by reconstructing each position with the amplitude of the channels’ output signals. The corresponding accuracy is $231\pm 4\mu \mathrm{m}$.