GB741365A - Improvements in or relating to electron multipliers - Google Patents

Abstract

741,365. Discharge devices. ELECTRIC & MUSICAL INDUSTRIES, Ltd. May 7, 1953 [May 27, 1952], No. 13371/52. Class 39 (1). A single stage or multi-stage electron multiplier device includes an opaque metallic photocathode 7 arranged between an apertured dynode electrode 5 and a further electrode, which may either be one of the dynodes 8 or the collecting electrode 9, the apertured dynode electrode 5 being a metallic annulus arranged with its active surface facing the cathode 7 and through the aperture in which light can pass to the cathode and the arrangement being such that with suitable potentials applied to the electrodes, electrons are released from the cathode and are directed on to the dynode 5 to release secondary electrons which are directed past the cathode 7 on to the further electrode. A tubular flanged electrode 15 is arranged between the dynode 5 and the further electrode 8 to focus the electrons emitted by the dynode 5 on to the dynode 8. The active surface of the photo-cathode 7 may be flat, convex or concave and the cathode is supported by radial wires 7a. The electrostatic field conditions are arranged so that the electrons emitted by the cathode 7 are directed away from the aperture 6 in the dynode 5. A translucent conductive coating 17 of stannous chloride, having a contact 18 and connected by a strap 19 to the cathode 7 may be provided on the wall 2 of the device through which light passes to the cathode 7 for setting up an electric field preventing electrons from the cathode 7 from passing through the aperture in the dynode 5. The electrodes and dynodes, which are of the louvre type, are supported in insulating rods 13. With a concave cathode it is preferably arranged that a cross-over point is located between the cathode and the dynode 5. Dimensions are given.