| 摘要 |
969, 861. Measuring radiation. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. Sept. 4, 1962 [Sept. 6, 1961], No. 32029/61. Heading G1A. [Also in Division H3] The concentration of uranium-235, uranium 238 and plutonium-239 in the atmosphere are determined by an alpha particle detector in the form of a reversed biased surface barrier or PN junction semi-conductor device SSD whose output is applied through an amplifier to a plurality of pulse height selectors 1, 2, 3 each arranged to produce an output in response to pulses falling within a predetermined range corresponding to the alpha particle energies of the elements to be monitered, a switching means S1 S2, S3 being provided to permit a desired selector to be connected to a scaler. The switching means may comprise push buttons or a switch mechanism for connecting the selectors to the scaler in sequence. A variable range channel may be provided for monitoring alpha activity of isotopes other than those referred to above. The output of the scaler may be recorded by an electro-mechanical register having print wheels for giving a printed tape output. Detailed circuits for the pulse height selectors are described (see Division H3). Reference is made to the use of germanium or silicon diffused with lithium for the semi-conductor detector.
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