Abstract: 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.

Abstract: A channel secondary electron multiplier has a mechanically sturdy body made of metal or ceramic material. The body forms an internal multiplier channel having a curved, e.g. helical main portion and a funnel shaped entrance end. A resistive layer forming a secondary electron emissive surface is provided on the inner wall of said channel inclusive that entrance end. The secondary electron emissive resistive layer in said funnel shaped entrance end has the form of a spiral-shaped band or stripe having a width which is preferably at least approximately equal to the circumferential dimension of the main portion of said channel. The body has a thermal coefficient of expansion which is at least 15% larger than the thermal coefficient of expansion of said layer, to maintain said layer under compression.