Dynamic switching of a detector switch matrix

A charged particle detector includes an array of sensing elements that may be selectively grouped with each other by a switch matrix. The sensing elements may be grouped in a shape and location that corresponds to an expected shape and location of beam spot to be detected. During a detection process, the grouping of sensing elements may be updated in real time. Updating may include both adding peripheral sensing elements to the group, as well as removing peripheral sensing elements from the group. A sensing element may be added if it is determined to be receiving sufficient irradiation from the beam spot. A sensing element may be removed if it is determined to not be receiving sufficient irradiation from the beam spot. The determination may be made by a thresholding circuit located within each sensing element.