Radiation detector and radiation detector array

A radiation detector comprising:

• a scintillator including a pair of end surfaces opposing each other in a first direction, a first side surface coupling the pair of end surfaces, and a second side surface coupling the pair of end surfaces and being adjacent to the first side surface;
• a first semiconductor photodetector including a first semiconductor substrate disposed to oppose the first side surface;
• a second semiconductor photodetector including a second semiconductor substrate disposed to oppose the second side surface;
• a first wiring member electrically connected to the first semiconductor photodetector;
• and
• a second wiring member electrically connected to the second semiconductor photodetector, wherein
• the scintillator has a rectangular shape when viewed in the first direction,
• a length of the scintillator in the first direction is longer than both of a length of the scintillator in a second direction orthogonal to the first side surface and a length of the scintillator in a third direction orthogonal to the second side surface,
• a length of the first side surface in the first direction is longer than a width of the first side surface in the third direction,
• a length of the second side surface in the first direction is longer than a width of the second side surface in the second direction,
• each of the first semiconductor substrate and the second semiconductor substrate includes a first portion covered with a corresponding side surface of the first side surface and the second side surface and a second portion exposed from the corresponding side surface,
• the first portion and the second portion are disposed in the first direction,
• each of the first semiconductor photodetector and the second semiconductor photodetector includes a photodetection region disposed in the first portion, and a first electrode and a second electrode disposed in the second portion,
• each of the photodetection regions includes a plurality of avalanche photodiodes arranged to operate in Geiger mode and a plurality of quenching resistors electrically connected in series with one of an anode or a cathode of a corresponding avalanche photodiode of the plurality of avalanche photodiodes,
• the plurality of quenching resistors are connected in parallel with the first electrode,
• another of the anode or the cathode of each of the plurality of avalanche photodiodes is electrically connected in parallel with the second electrode, and
• each of the first wiring member and the second wiring member includes a conductor electrically connected to the first electrode and a conductor connected to the second electrode.