Abstract:
The present invention provides a method for manufacturing radiation detectors such as Geiger-Müller detectors. The method includes pre-forming a frit ring via extrusion or stamping. The preformed frit ring is placed in the aperture of a metal cathode body along with a radiation transparent window made of mica. The window is slightly larger than the perimeter of the aperture, thereby forming an overlap area. The frit ring is placed between the cathode and window within this overlap area. The assembled components are then fired at an appropriate temperature to cause fusion of the frit with the metal cathode and window to form a gas-tight seal.
Abstract:
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.
Abstract:
For simultaneously measuring the radioactivity of multiple samples arranged in a predetermined array of x rows and y columns, a fixed array of radiation counters arranged in the same array of x rows and y columns so that one of the counters is aligned with each of the multiple samples. Each of the counters has a pair of spaced electrodes; an electrical voltage source connected to the electrodes of all the counters for applying the same voltage across the electrodes of each of the radiation counters in the array; and sensing means connected to the electrodes of each of the radiation counters for independently detecting pulses of electrical current produced by ionization of the gas between the respective pairs of electrodes of each of the radiation counters. For measuring low-energy radiation, the radiation counters are windowless, a flow of ionizable gas is supplied to the counters, and the same flow rate of the ionizable gas is maintained through each of the radiation counters in the array. Preferably the radiation counters are formed in a metal plate that provides shielding to minimize "cross talk" between adjacent samples.
Abstract:
An improved Geiger Müller tube comprises an enclosed container having at least one metal wall forming a cathode, said metal wall comprising a layer of platinum, a metal anode spaced from said cathode, and means to apply a voltage between said anode and said cathode, said enclosed container being filled with a gas mixture comprising a noble gas and a halogen comprising chlorine, bromine or a mixture thereofto a pressure of less than 0.2 atmospheres, characterised in that said platinum comprises a surface layer of platinum tetrachlorideand/or platinum tetrabromidehaving a thickness of at least 10 nm.
Abstract:
A detector probe, for detecting ionising radiation and which is suitable for use in a nucleonic instrument usable in locations having a high ambient temperature, comprises an array of radiation detectors mounted on a support and a heat pipe for cooling the detector probe. The invention further comprises a nucleonic instrument incorporating such a detector probe.
Abstract:
A substantially stable, substantially portable open window gas flow Geiger-Mueller type detector which is capable of monitoring ionizing radiation is described as well as a method for monitoring ionizing radiation.