Patent ID: 7498741
Filing Date: 2009-03-03
Classification: H01J

Abstract:
1. A photomultiplier comprising: a sealed container of which the inside is kept in a vacuum state; a photocathode, accommodated in said sealed container, for emitting photoelectrons to the inside of said sealed container in response to light having a predetermined wavelength; a dynode unit accommodated in said sealed container and including a plurality of stages of dynodes for emitting secondary electrons in response to the photoelectrons reached from said photocathode to cascade-multiply sequentially the secondary electrons; an anode, accommodated in said sealed container, for taking the secondary electrons cascade-multiplied by said dynode unit as a signal; a pair of insulating support members for holding unitedly said dynode unit and said anode in a state grasping said dynode unit and said anode; a focusing electrode arranged between said photocathode and said dynode unit and having a through hole through which the photoelectrons from said photocathode pass, said focusing electrode for correcting an orbit of each photoelectron from said photocathode; and an accelerating electrode, arranged between said focusing electrode and said dynode unit, and having a through hole through which the photoelectrons reached from said photocathode via said focusing electrode pass, said accelerating electrode for accelerating the photoelectrons reached from said photocathode via said focusing electrode, wherein said accelerating electrode has: a lower electrode that is held by said pair of insulating support members in a state for said pair of insulating support members to grasp unitedly it together with said dynode unit and said anode; and an upper electrode having one or more slit grooves pinching a part of said pair of insulating support members and being attached to said lower electrode in a state for said slit grooves to pinch a part of said pair of insulating support members.