PURPOSE: To extend a spectral sensitivity range by dividing tube walls of each channel of a microchannel plate to the circumferential direction, forming photoelectron discharging layers different in spectral sensitivities, and inclining the plate against a radiation source to enable the selection of the photoelectron discharging layers.

CONSTITUTION: The photon discharging layers 22 of CsI and said layers 23 of RbBr are formed at one side and another side of inputting side of each channel 21 of the microchannel plate 20 respectively. A fluorescent surface 25 formed on a surface of a fiber plate 26 is allowed to correspond to an output surface of the plate 20, and the luminescence of the surface 25 is subjected to photoelectric conversion by a photoelectric conversion element 27 and outputted. Further, the plate 20 and the surface 25 are contained in a vacuum vessel 30, and the plate 20 is supported so that two angle positions are maintained against a radiation source 31.