title: Characterisation of the IRSN graphite moderated Americium-Beryllium neutron field.
abstract: The SIGMA facility was set up at IRSN to provide thermal neutrons for metrology and dosimetry purposes. SIGMA consists of six Am-Be radioactive sources located in a 1.5 x 1.5 x 1.5 m3 graphite moderator block. The neutron field at the calibration position, situated at 50 cm from the west surface of the assembly was characterised experimentally and by Monte Carlo calculations. The thermal neutron fluence was determined by the activation of gold foils; the neutron fluence energy distribution above 240 keV was measured with proton recoil spectrometers and the neutron fluence energy distribution from thermal energies to 20 MeV was measured with a Bonner spheres spectrometer. A Monte Carlo simulation of the SIGMA assembly was undertaken using the MCNP4C code, and the calculated neutron fluence energy distribution was compared with the measurements. As a whole, the experimental data and the MCNP calculation are in a good agreement.
authors.affiliation: Institut de Radioprotection et de Sûreté Nucléaire, BP 3, 13115 Saint-Paul-Lez-Durance, France. Veronique.Lacoste@irsn.fr
authors.forename: V
authors.initials: V
authors.lastname: Lacoste
authors.forename: V
authors.initials: V
authors.lastname: Gressier
authors.forename: H
authors.initials: H
authors.lastname: Muller
authors.forename: L
authors.initials: L
authors.lastname: Lebreton
mesh_terms: D000465:Algorithms; D000576:Americium / Q000032:analysis*; D001608:Beryllium / Q000032:analysis*; D001822:Body Burden; D002138:Calibration / Q000592:standards; D003198:Computer Simulation; D017076:Computer-Aided Design; D019544:Equipment Failure Analysis / Q000295:instrumentation / Q000379:methods / Q000592:standards; D005602:France; D006108:Graphite; D038622:Internationality; D015233:Models, Statistical; D009010:Monte Carlo Method; D009502:Neutrons; D009688:Nuclear Reactors; D016273:Occupational Exposure / Q000032:analysis; D017785:Photons; D011829:Radiation Dosage; D011835:Radiation Protection / Q000295:instrumentation / Q000379:methods* / Q000592:standards*; D011868:Radioisotopes / Q000032:analysis; D011874:Radiometry / Q000295:instrumentation / Q000379:methods* / Q000592:standards*; D012015:Reference Standards; D012062:Relative Biological Effectiveness; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity
chemical_list: D011868:Radioisotopes; D006108:Graphite; D001608:Beryllium; D000576:Americium