Patent ID: 7564043

Claim:
An MCP unit comprising: a micro-channel plate, for releasing secondary electrons internally multiplied in response to incidence of charged particles, arranged on a plane that intersects a predetermined reference axis, said micro-channel plate having an incident surface upon which the charged particles are incident, and an exit surface that opposes the incident surface and emits the secondary electrons; a first electrode being in contact with the incident surface of said micro-channel plate, said first electrode being set to a predetermined potential; a second electrode being in contact with the exit surface of said micro-channel plate, said second electrode being set higher in potential than said first electrode; an anode arranged in a position where the secondary electrons released from the exit surface of said micro-channel plate reach, in a state to intersect the reference axis, said anode being set higher in potential than said second electrode; and an acceleration electrode arranged between said micro-channel plate and said anode such that a shortest distance to said anode is longer than a shortest distance to the exit surface of said micro-channel plate, said acceleration electrode being set higher in potential than said second electrode and having a plurality of openings which permit passing of the secondary electrons migrating from the exit surface of said micro-channel plate toward said anode.