GB732685A - Improvements in or relating to radiation detectors - Google Patents

Abstract

732,685. Geiger counters. UNITED KING- DOM ATOMIC ENERGY AUTHORITY. June 22, 1953 [June 24, 1952; June 24, 1952], Nos. 15838/52 and 15839/52. Class 39 (1). (Also in Group XXIII] A radiation counter, primarily intended for the detection of neutrons comprises a cylindrical metal can 1 having a circumferential groove 2, or alternatively a series of dimples, near the base 3. A brass ring 4 holding a disc 5 of polymerized poly-tetra fluorethylene insulating material is held against the side of the groove 2 by a circlip 6 which is sprung into a groove 7 in the wall of the can 1. The mouth of the can 1 has a cover 11 supporting a collar 12 to which is sealed a glass bulb 14. An anode wire 8 is sealed at one end in the head 10 of a glass tube 9 supported by the disc 5 and at the other end is spot welded to a nickel wire 15 sealed through the bulb 14. The wire 15 terminates in a coaxial type plug 16 fixed by means of screws to a metal tube 17 which is sealed to the cover 11. The counter has a filling of boron-tri-fluoride and the inner wall of the can 1 may have a coating of a solid fluoride such as sodium fluoride made adherent by vacuum vaporization capable of absorbing hydrofluoric acid whilst being inert to the gaseous fluoride filling. The tube 17 may be filled with a plugging compound comprising a paste-like mixture of moisture and gas-free powdered high-quality insulating material and a resin-free low vapour pressure hydrocarbon grease or oil or silicone oil, as described in Specification 731,060, [Group V]. A special tool (see Group XXIII) may be used to introduce the anode assembly into the envelope and to clip the circlip 6 in position in the groove 7.