Geiger-Muller tubes their manufacture and systems comprising them

摘要

A Geiger-Muller tube designed for use in an environment (for example, mounted on a rock drill) where subjected to mechanical shock and vibration has a tensioned anode wire (1) secured between first and second mounts (11,21) and (12,22) at opposite ends of the tube envelope. The wire tension is adjusted to a high value with a screwible-adjustment means (22,23,24) which is locked (*25) in the adjusted position, so that the natural frequency of vibration of the tensioned wire 1 does not resonate with (and may be much higher than) the frequencies to which the tube is subjected in use. The wire frequency is typically in excess of 400Hz and even 500Hz. The adjustment means (22,23,24) may be included in the mount (12,22) via which the envelope is evacuated and back-filled with the ionizible gas, and a gas-tight seal (30) can be provided around this part of the mount (12,22), for example by sealing off the gas pump tube. However the adjustment means may be designed into another part of the tube, for example using telescopic parts of the envelope whose sliding junction is made gas tight with a flexible seal.