Patent ID: 7990064
Filing Date: 2011-08-02
Classification: H01J

Abstract:
1. A photomultiplier comprising: a sealed container including a hollow body section extending along a predetermined tube axis and a faceplate provided so as to intersect the tube axis said faceplate transmitting light with a predetermined wavelength; a photocathode provided inside said sealed container so as to emit photoelectrons into said sealed container in response to incidence of the light with the predetermined wavelength; a dynode unit provided inside said sealed container so as to cascade-multiply photoelectrons emitted from said photocathode said dynode unit including at least one dynode set being constituted by a plurality of dynodes that respectively have a single secondary electron emitting surface, said one dynode set including, at least, a first dynode emitting secondary electrons in response to incidence of photoelectrons, and a second dynode receiving secondary electrons from said first dynode and arranged such that the single secondary electron emitting surface of said second dynode faces that of said first dynode; and a partitioning plate comprised of a conductive material and partitioning the single secondary electron emitting surface of said second dynode into two in a longitudinal direction of said second dynode said partitioning plate extending in a direction directed from said photocathode to said dynode unit such that a tip thereof is positioned in a space between the single secondary electron emitting surfaces of said first and second dynodes; and a focusing electrode unit arranged between said photocathode and said dynode unit, wherein said partitioning plate includes a metal tab of said focusing electrode unit that extends in a direction directed from said photocathode to said dynode unit, wherein said second dynode has a slit that puts a front surface, on which its single secondary electron emitting surface is formed, in communication with a back surface that opposes the front surface, and wherein said metal tab of said focusing electrode unit extends in the direction directed from said photocathode to said dynode unit such that the tip thereof is positioned, via said slit of said second dynode, in the space between the single secondary electron emitting surfaces of said first and second dynodes.