An improved apparatus for demonstrating the presence of supernormal radioactive radiation

摘要

661,814. Detecting radio-activity. GRAFFUNDER, W. H. July 14, 1949 [July 14, 1948; Feb. 1, 1949 and May 14, 1949], Nos. 18626/49; 18627/49, 18628/49. Class 40 (iii). A warning is operated when radio-activity in a particular region exceeds a mean adjustable level. Voltage pulses from an A.C. fed Geiger- Muller counter or ionization chamber may be used to charge a condenser in parallel with a leakage resistance so that if the condenser voltage exceeds an adjustable mean value a thyratron is triggered to operate a relay. A further relay may discharge the condenser so that the condenser is recharged if the radiation level does not fall and the apparatus gives periodic warnings. To lengthen the counter output pulses they may be applied to an A.C. fed thyratron before being integrated in the condenser, the thyratron firing at each pulse and remaining conductive until its plate voltage passes below zero. If an ionization chamber is used the chamber may be operated at a high potential but connected only intermittently to the amplifying circuit. The ionization chamber may be provided with a cover to retain radioactive dust, this cover being permeable to X-rays. It may for example be made of " Cellophane " (Registered Trade Mark) sheets or leaves, possibly supported by wire gauze.