V.V. Kudryashyov, Dr. Sci. (Eng.), Prof., Lead Researcher, kudr_ipkon@mail.ru IPKON RAN, Moscow, Russia
Analytical relationship is established between the fraction of radiation from the circular source incident on the circular and annular detectors with the dimensions of the source, the radiation receiver, and the distance between them. Obtained dependences quite well describe the nature of the established links. They can be used to calculate the parameters of radiometric units of the instruments and allow solving other problems of interaction between the sources and radiation receivers, for example, to propose the methods of identifying the intensity and the dimensions of the radiation source. The calculation is based on the dead time value of the detector. Knowing the dead time of the detector, it is possible to calculate the maximum permissible intensity of the radiation incident on the detector, and at the selected geometric parameters of the detector to calculate the radiation intensity of the source, i.e., without conducting the experiment it is possible to determine detector parameters. The methods are required at the development and verification of the radionuclide sources. The considered radiometric scheme was used at the development of two types of detectors for dust deposition continuous control. Both use the direct absorption of beta particles by dust deposited on the thin collector-substrate. In case of the first option of the detector there are movable parts that move the collector to the radiometric unit and to the position for dust deposition. Another type of detector is very simple — it does not have any moving elements. The radiometric unit is combined with the dust collector. It is convenient for placing on the surface where dust is deposited, and for installing it with respect to the direction of the dust flux. The disadvantage of the detector is the openness of the source. However it is shielded by a seat from the side facing away from the working surface.
In the sensors it is proposed to use the radionuclide carbon-14, which belongs to the lowest group of radiation hazard for the person «G». At the same time, the radiation intensity of the source (1·104 s–1) is thousandfold greater than the radiation background from the dust of coals of different mine deposits.
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