Ionizing radiation is widely utilized in a variety of fields, e.g. medical diagnostics and therapy, sterilization of medical devices, radiation processing of foods and some materials, electric power plants, and several kinds of analyses as well as researches and developments.  It is necessary to evaluate accurately the quantity of radiation in order to utilize radiations efficiently and to protect ourselves from excess irradiation to human bodies.  We are studying precise measurement techniques of ionizing radiation, establishing several standards and disseminating them.

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Dosimetry :  Standardization of ionizing radiation like X-rays and g-rays has been established and the dissemination of the standards is carried out.  The technique of this establishment depends on the precise measurements of ions produced in the air upon irradiation of photon beams.  The units used are exposure, C/kg, air kerma, Gy (= J/kg), and absorbed dose of air, Gy.  Researches are being performed for standards of b-rays and soft X-rays using synchrotron radiation, together with more reliable standards of X-rays and g-rays.[Ionizing Radiation Section]

Radioactivity :   Techniques for accurate measurements of ionizing radiation like a-particle, β-ray and γ-ray have been developed and standards for these radiations have been established, maintained and disseminated in a wide range from environmental levels to therapy levels.  The units disseminated are Bq and the quantities derived from Bq, which defines the number of disintegration per one second of radio-isotopes.  Researches are carried out for provision of radioactive sources in order to transfer the primary standards. [Radioactivity & Neutron Section]

Neutron :  Techniques of measurements of a non-charged particle, neutron, have been developed and several standards have been established, maintained and disseminated for units of neutron emission rate (s^-1) and neutron fluences in wide energy ranges (m^-2).  The emission rate from radioactive sources like Cf-252 and Am-Be is realized using a manganese sulfate bath and fast neutron fluences are done through nuclear reactions of some targets irradiated with ion beams from a van de Graff accelerator or a Cockcroft-Walton type.  Researches are carried out for standards of mono-energetic neutron fluences in other energy points [Radioactivity & Neutron Section].