State primary standard of units of absorbed dose, absorbed dose rate, ambient and individual dose equivalents, rates of ambient and individual dose equivalents of neutron radiation GET 117-2023

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The issues related to ensuring the uniformity of measurements and traceability of measurement results obtained using clinical dosimeters in neutron radiation therapy are considered in relation to the State Primary Standard of units of absorbed dose, absorbed dose rate, ambient and individual dose equivalents, ambient and individual dose equivalent rates of neutron radiation GET 117-2023. The methods and means of reproduction and transmission of units of ambient and individual equivalents of neutron radiation dose and their powers are described. Reproduction of these units of quantities is carried out on the basis of the reconstructed energy distribution of neutrons in the energy range of 0.001–20 MeV. Requirements for the measurement error of these units of quantities are presented, in particular, the relative expanded uncertainty of measuring the absorbed dose and the absorbed dose rate of neutron radiation should not exceed 3 % with a coverage factor of 2. The work describes the composition and physical principles of operation of the State Primary Standard. The standard includes new technical means: hardware and methodological complexes for reproduction, methods and means of measurement, a neutron radiation verification unit with an automated positioning system for neutron radiation sources UKPN-1MDA, a system for filling chambers with gases. The authors present a description of the methods for reproducing units of quantities and their functional dependence. The results of the study of the metrological characteristics of GET 117-2023 are presented. The metrological characteristics of the updated standard correspond to modern domestic and international standards for accuracy and reproduction ranges. The uniformity of measurements of clinical dosimeters required for neutron radiation therapy has been ensured. GET 117-2023 plays a key role in the system of metrological support for dosimetric measurements of neutron radiation in such areas as healthcare, ecology, nuclear energy, industry, defense and security, science, as well as in a number of other areas.