One embodiment provides a method, including: receiving a plurality of responses to an interaction occurring within a photon detector pixel array, wherein the photon detector pixel array comprises a plurality of pixels; identifying a subset of the plurality of pixels associated with the interaction, wherein each of the subset of the plurality of pixels corresponds to at least one of the plurality of responses; and determining, from the plurality of responses, a characteristic of the interaction, wherein the characteristic comprises at least one of: time, position, and energy of the interaction. Other aspects are described and claimed.