A detector of a high-energy photon, the detector including a photodetector and a detection medium that is intended to absorb a high-energy photon while generating ionization electrons and photons along a luminous phenomenon, the electrons and photons being detected by the photodetector. The detection medium is formed of molecules, having a heavy atom with an atomic number greater than or equal to 72, such that the detection medium is liquid under the operating conditions of the detector. The detector also includes a device for diverting the ionization electrons that are generated by the absorbed photon and moreover includes a collector that collects charges in order to determine the time for diverting the electrons to the charge-collector on the basis of a triggering time that corresponds to the detection of the luminous phenomenon by the photodetector.