Determination of the anisotropic emission factor for neutrons from Am-Be source

Kowatari, Munehiko; Onuma, Isamu; Tanimura, Yoshihiko   ; Kawasaki, Katsuya ; Saegusa, Jun; Yoshizawa, Michio  

The neutron standard field using Am-Be neutron source has been widely used for the routine calibration of neutron dosemeters. The neutron fluence rate at the calibration point is one of the most essential parameters. For the precise determination of the neutron fluence rate, the effect defined as an anisotropic emission from the neutron source, F(), should be taken into account. For the proper calibration of the neutron dosemeters used in the Japan Atomic Energy Agency (JAEA), the anisotropic factor F(90) from an Am-Be neutron source was experimentally determined using the precision long counter. Before the determination of the anisotropic factor of the Am-Be source with the protection case, the measured angular distribution from the X3 type Am-Be source was compared with the result obtained by other researchers and with the Monte Carlo calculation using MCNP-4C, for the verification of the method the authors adopted.