title: Development of the fast neutron standard using a Be({alpha},n) reaction at the National Metrology Institute of Japan.
abstract: This paper describes the 8-MeV neutron field where the neutrons are generated in the (9)Be(alpha,n)(12)C reaction by bombardment of a beryllium target with a 2.4-MeV (4)He(+) beam from a Van de Graaff accelerator. The neutron field is being prepared for a new national standard on neutron fluence in Japan. Absolute measurement of the neutron fluence was taken using a proton recoil neutron detector, consisting of a silicon surface barrier detector with a polyethylene radiator. Neutron spectra were measured using a newly developed recoil proton spectrometer and a liquid organic scintillation detector. The gamma rays existing in the field were also characterised using a liquid organic scintillation detector. The ambient dose equivalents of the gamma rays were estimated to be <100 microSv at the neutron fluence of 10(7) neutrons cm(-2).
authors.affiliation: National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan. tetu-shimoyama@aist.go.jp
authors.forename: T
authors.initials: T
authors.lastname: Shimoyama
authors.forename: H
authors.initials: H
authors.lastname: Harano
authors.forename: T
authors.initials: T
authors.lastname: Matsumoto
authors.forename: K
authors.initials: K
authors.lastname: Moriyama
authors.forename: T
authors.initials: T
authors.lastname: Hata
authors.forename: K
authors.initials: K
authors.lastname: Kudo
authors.forename: T
authors.initials: T
authors.lastname: Koyamada
authors.forename: A
authors.initials: A
authors.lastname: Uritani
mesh_terms: D001608:Beryllium / Q000737:chemistry* / Q000528:radiation effects*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007564:Japan; D009502:Neutrons; D010315:Particle Accelerators / Q000295:instrumentation* / Q000592:standards*; D011829:Radiation Dosage; D011874:Radiometry / Q000295:instrumentation* / Q000592:standards*; D012015:Reference Standards
chemical_list: D001608:Beryllium