Low capacity, photodiode radiation detector and photographic apparatus comprising such a detector

The invention concerns a radiation detector with a photodiode. The detector functions by converting the incident radiation into free charges carrying the signal picked up by the electrodes of the photodiode. The applications of such detectors are very diverse according to the nature of the radiation they have to detect, X or γ radiation in medical work for straight radiology, computer assisted tomography, scintiscanning, etc. or flow of ionizing particles in the nuclear field. In every case, a scintillator receives the incident radiation and changes it into a photonic radiation which acts on a photodiode applied against the scintillator, the signal of the photodiode serves as measurement to the incident radiation. For this measurement, particularly for noise reasons, a low photodiode capacity is sought. According to the invention, the reduction in capacity sought is achieved by using a photodiode split into a network of small unit photodiodes, formed in the same substrate applied against the scintillator and each having a reduced capacity owing to these dimensions. The electrodes of the photodiodes pick up the free charges moving in the substrate by lateral collection. This network is distributed on the substrate within the perimeter limiting the incident photonic radiation