| 摘要 |
A particle and photon detector includes a body having a beam-incident surface (8) capable of releasing secondary electrons in numbers proportional to the number of particles incident on the surface, and a plurality of secondary electron multiplier channels (4) whose inlet openings are disposed in the beam-incident surface, therewith to amplify the number of secondary electrons. A center channel (2) extends from the beam-incident surface (8) through the detector body and enables a beam of particles or photons to pass through the body. The inlet openings of the secondary electron multipliers are conveniently disposed in the beam-incident surface in a ring around the center channel for receiving secondary electrons. The method applied in the detection of charged particles, such as ions and electrons, in a beam that contains charged and charge-free particles comprises the steps of subjecting the charged particles to the effect of an electric field so as to collect the charged particles in an outer tubular layer or beam which surrounds the residual beam of charge-free particles, such as to form two mutually, coaxial beams, wherein the outer tubular particle beam is captured by a plurality of secondary electron multipliers and wherein signals delivered by the electron multipliers are read-off. |
