Patent ID: 7838810
Filing Date: 2010-11-23
Classification: H01J

Abstract:
1. A photomultiplier tube comprising: a vacuum vessel having a faceplate constituting one end and a stem constituting another end; a photocathode that converts incident light incident through the faceplate to electrons; an electron multiplying section that multiplies the electrons emitted from the photocathode; an electron detecting section that transmits output signals in response to electrons from the electron multiplying section, wherein the photocathode, the electron multiplying section, and the electron detecting section are provided within the vacuum vessel, characterized in that the stem is made from an insulating material and having a first surface opposing the electron multiplying section and a second surface opposing the first surface; the stem is provided with an air discharging tube that has an outer side tube and an inner side tube provided coaxially, the outer side tube having a first thickness, the inner side tube having a second thickness thinner than the first thickness; and an outer circumferential surface of the outer side tube is hermetically joined with the stem, the outer side tube having a first outer end facing inside of the vacuum vessel, the inner side tube having a first inner end facing inside of the vacuum vessel, the first outer end and the first inner end being connected.