 Main Research Themes |
| 1. Development standardization and dissemination of dosimetry : Based on the traceability system of the Measurement Law, JCSS, standards of X-rays and γ-rays are supplied into accredited oraganizations. Standardization is performed more precisely and then international comparison with BIPM or a national institute of metrology in developped countries is carried out for requirement of the Mutual Recognition Arrangement based on the Meter Convention. Cylindrical graphite chambers are utilized for realization of the exposure standards on Co-60 and Cs-137 γ-rays. Parallel plates free air chambers combined with several sets of filter plates are used for the standards on X-rays in the energy region from 8keV to 200 keV. |
| 2. Absolute measurements of mono-energetic X-rays from synchrotron radiation
: Synchrotron radiation from the electron storage ring at AIST is monochromatized with a double quasi-crystal consisting of synthetic multi-layered structures, which have been fabricated from a light element and a heavy element using a helicon sputtering technique. One aim is to compare the fluence standard with the exposure in the keV energy region, and another is to develop qualified standards of X-rays in higher energy regions by the extention of the present technique. |
| 3. Standardization of some ionizing radiation used in advanced research
fields : Photon fluence of sub-keV energy is measured on an absolute scale using monochromtized synchrotron radiation and a multi-electrode ion chamber. The ion chamber is supplied with a rare gas, and then a factor (γ-value ) related to multiple photoionization is utilized for realization of the absolute fluence rate (m-2s-1). The related physical quantities like W-value and photoabsorption cross-section are precisely determined as well as clarification of mechanisms of multiple ionization of rare gas atoms. X-rays from the conventional X-ray tubes are utilized for precise standardizations of air kerma and exposure beyond energy regions having the established standards. |