Accelerator-based Neutron Fluence Standard of the National Metrology Institute of Japan

摘要

We report the present status of the national standard on accelerator-based fast neutron fluences in Japan.Monoenergetic neutron fluence standards have been established at 144 keV, 565 keV, 5.0 MeV and 8.0 MeV by using aVan de Graaff accelerator and at 2.5 MeV and 14.8 MeV by using a Cockcroft Walton accelerator. These standards areprepared to measure the detection efficiency and the energy response of neutron sensitive devices, such as personaldosimeters and survey meters. Neutron production and absolute fluence measurement for these energies are described.We are developing a new standard in the energy region of a few tens of keV, which is also introduced here as well as ourfuture plans.