FIELD: physics.
SUBSTANCE: radiation detector includes an array of detector pixels (22) each including an array of detector cells (50, 50', 50"). Each detector cell includes a photodiode (52) based in the breakdown region and digital circuitry (54, 54', 54") connected to the photodiode and configured to output a first digital value in a quiescent state and a second digital value responsive to photon detection by the photodiode. Digital triggering circuitry (60, 60', 60", 84) is configured to output a trigger signal indicative of the beginning of integration time period in response to a selected number of one or more of the detector cells switching from the first digital value to the second digital value. Readout digital circuitry (66, 82) accumulates a count of a number of transitions of detector cells of the array of detector cells from the first digital state to the second digital state over the integration time period.
EFFECT: high resolution of the detector.
41 cl, 13 dwg
