A radioisotope neutron source and its application for dosimetry

A various kinds of radioactive neutron sources have been developed since neutron had been first discovered. The reactions which are mainly taken advantage for generating neutrons as radioactive neutron source are (α,n) reaction, (γ,n) reaction and nuclear fission reaction. Only ²⁴¹Am-Be and ²⁵²Cf neutron sources are now available due to reliable reproducibility of neutron emission, long half-lives and less disturbing gamma ray emission. Both are designated as a 'reference neutron source' by ISO 8529 series describing principle of establishment of neutron calibration field. Total neutron emission rate from neutron source must be well defined in terms of sophisticated method by national metrological laboratory. In order to serve a reliable neutron calibration field produced by a RI neutron source, correction factor for anisotropic emission from cylindrical-shaped neutron source must be experimentally determined for neutron fluence rate at a point of test in the calibration laboratory. (author)