GB1333850A - Drift monitoring apparatus for ionisation chambers - Google Patents

Abstract

1333850 Monitoring drift in ionization chambers COMMISSARIAT A L'ENERGIE ATOMIQUE 19 April 1971 [26 March 1970] 25300/71 Heading G1A To check for any drift in a measuring ionization chamber 2 there is provided in parallel therewith a reference chamber 1 incorporating a radio-active source of long half-life and low penetration, a switching device 4 being arranged between the monitor and an electro-meter assembly 3. By connecting the two chambers in parallel - upper switch position - the insulation of the measuring electrodes 7 and the electro-meter assembly, whose output is presented on a recorder 6, can be tested simultaneously. In the lower switch position the chamber 2 can be used for measuring purposes. The two chambers may be linked to have a common atmosphere Fig. 2 (not shown) or may share a common housing Fig. 3 (not shown). In these embodiments the radio-active source is arranged so that its radiation cannot emerge from the HT electrode of the monitor and hence introduce background noise into the measuring chamber. The radio-active source in the monitor may be provided by covering its HT electrode (II) with a C14 #-emitter (12) Fig. 5 (not shown). Alternatively, the #-source may be an electrolytic deposit (26) of Am241 on a stainless steel support Fig. 7 (not shown).