Abstract: A channel electron multiplier is described having a tubular wall coated w a secondary-electron emitting material and including an electric field for accelerating the electrons, the electric field comprising a plurality of low-resistive conductive rings each alternating with a high-resistive insulating ring. The thickness of the low-resistive rings is many times larger than that of the high-resistive rings, being in the order of tens of microns for the low-resistive rings and at least one order of magnitude lower for the high-resistive rings; and the diameter of the channel tubular walls is also many times larger than the thickness of the high-resistive rings. Both single-channel and multiple-channel electron multipliers are described. A very important advantage, particularly in making multiple-channel multipliers, is the simplicity of the procedure that may be used in constructing such multipliers. Other operational advantages are described.

Abstract: A gamma-ray camera is described including a collimator receiving and collimating the gamma rays, a converter matrix converting the gamma rays to electrons, an electron-image multiplier receiving the electrons and producing a multiplied electron output, and means for reading out the output of the electron-image multiplier.A converter matrix is described for converting gamma-rays to electrons comprising a metal plate emitting electrons upon being impinged by gamma-photons, the metal plate having a face formed with a plurality of spaced parallel surfaces which extend substantially parallel to the direction of the gamma-rays. Also described is a converter matrix of scintillation crystals, one face of each crystal including a photo-sensitive coating, the opposite face of each crystal being clear, the remaining faces of each crystal being coated with a light-reflecting coating.