Patent attributes
A photomultiplier tube, a photomultiplier tube unit, and a performance-improved radiation detector for increasing a fixing area of a side tube in a faceplate while increasing an effective sensitive area of the faceplate. In the photomultiplier tube, a side face (3c) of the faceplate (3) protrudes outward from an outer side wall (2b) of a metal side tube (2), so that a light receiving area for receiving light passing through a light receiving face (3d) of the faceplate (3) is increased. The overhanging structure of the faceplate (3) is conceived based on a glass refractive index. The overhanging structure is aimed to receive light as much as possible which has not been received before. When the metal side tube (2) is fused to the glass faceplate (3), a fusing method is adopted due to joint between glass and metal. Joint operation between the faceplate (3) and the side tube (2) is reliably ensured. Accordingly, the overhanging structure of the faceplate (3) is effective.
