| 摘要 |
<p>831,545. Ionisation counters. ATOMIC ENERGY OF CANADA Ltd. April 1, 1957 [April 20, 1956], No. 10580/57. Class 39(1). [Also in Group XL(b)] The radiation detector tube comprises two counters of the Geiger Mueller type and 9 and 10, Figs. 2 and 3, are the anode and cathode of the first detector, 12 and 11 the anode and cathode of the second detector, the two cathodes being electrically joined externally. The tube is demountable to allow the material to be investigated to be deposited on the inner surface of the tube forming the cathode 10. This cathode consists of a tube of aluminium some 0À0008 inch thick and forms an alpha particle filter. After assembly the ionising gas is introduced at the valve 14. In operation the first detector is subjected to all the radiation produced by the particles emitted from the material under test but because of its operation on the proportional part of its characteristic it responds only to the alpha radiation. Because of the action of the alpha particle screen the second detector is subjected to beta radiation only. The detector tube forms part of radiation counter which measures the radiation from long lived alpha particle emitters, e.g. radium in the presence of radiation from short lived alpha particle emitters, e.g. the decay products of radar, in which the emission of an alpha particle is preceded by the emission of a beta particle. The circuit operation is described in Group XL(b).</p> |
