Calibration of X-Ray and Gamma-Ray Measuring Instruments

摘要

The calibration and irradiation of instruments that measure x-rays and gamma-raysare performed in terms of the physical quantity air-kerma. The calibrations are listed in the NIST Special Publication 250 Calibration Service Users Guide as calibrations 46010C through 46050S. The process for establishing calibration or correction factors for radiation detectors, charge sensitivity tests for high-gain electrometers, and irradiations of passive dosimeters is explained in this document. Calibrations are performed by comparing the instrument to a NIST primary standard, which include four free-air chambers for x-rays and cavity ionization chambers for cesium-137((sup 137)Cs) and cobalt-60 ((sup 60)Co) gamma rays. Details of the design and use of these standards are presented in this document, as well as, a description of the quality assurance checks, which are performed to assure the constancy of the standards and the accuracy of the calibrations and irradiations.