GB1273778A - Apparatus for making visible invisible radiation - Google Patents

Abstract

1,273,778. Spark chamber detectors. AGA A.B. 28 May, 1969 [30 May, 1968], No. 26909/69. Heading H1D. In apparatus for making visible invisible radiation, such as the flux density of γ-quanta or the two-dimensional distribution of #-particles, comprising a spark-chamber detector and an integrating recorder for providing an indication of the pattern of sparks, the electrode system of the spark chamber detector, Fig. 3, comprising an auxiliary electrode 30 mounted between a flat cathode 29 and anode 31 and connected directly to the cathode, is replaced by the system shown in Fig. 5, in which the auxiliary electrode 40 and anode 41 are fixed to metal rings 42 and 43 respectively and stretched along the upper and lower surfaces of an insulating support ring 44 having a thickness which gradually increases in a region around the central opening to a value equal to the required separation of the electrodes, e.g. between 0À5 and 9 mm. The said upper and lower surfaces of the ring 44 are coated with material of high conductivity to prevent sparking across the inner periphery of the ring. The metal ring 42 is separated by an insulating washer 35 from a metal supporting ring 23 and a collimator 24 on which the cathode 29 rests. Ring 23 and a ring 21 securing a window 22 are screwed to a metal cylinder 20 provided with a supply port for a gas, e.g. argon, and an insulated bush 26 for the power supply, and supporting an apertured gas distribution ring 28. The electrodes 40 and 41 may be of W gauze if the recorder is a camera. Alternatively the electrodes may be parallel wires to enable the pattern of sparks to be recorded by a digital recording circuit. In either case the wires of one electrode should not be parallel to those of the other. The cathode 29 may be of Ag or Au applied as a thin layer to a support of synthetic material. Alternatively the cathode may be mounted on a metal support, e.g. Cu, having a roughened surface.