title: Thermal neutron calibration channel at LNMRI/IRD.
abstract: The Brazilian Metrology Laboratory of Ionizing Radiations (LNMRI) standard thermal neutron flux facility was designed to provide uniform neutron fluence for calibration of small neutron detectors and individual dosemeters. This fluence is obtained by neutron moderation from four (241)Am-Be sources, each with 596 GBq, in a facility built with blocks of graphite/paraffin compound and high-purity carbon graphite. This study was carried out in two steps. In the first step, simulations using the MCNPX code on different geometric arrangements of moderator materials and neutron sources were performed. The quality of the resulting neutron fluence in terms of spectrum, cadmium ratio and gamma-neutron ratio was evaluated. In the second step, the system was assembled based on the results obtained on the simulations, and new measurements are being made. These measurements will validate the system, and other intercomparisons will ensure traceability to the International System of Units.
authors.affiliation: Universidade Federal do Rio de Janeiro, COPPE/UFRJ, Av. Horácio Macedo, 2030, Bloco G/Sala 206, Centro de Tecnologia, Cidade Universitária, Ilha do Fundão, CEP: 21941-914, Rio de Janeiro, RJ, Brazil Fundação Técnico Educacional Souza Marques, FTESM, Av. Ernani Cardoso, 335, Cascadura, CEP: 21310-310, Rio de Janeiro, RJ, Brazil achillesbr@gmail.com karla@ird.gov.br.
authors.forename: A
authors.initials: A
authors.lastname: Astuto
authors.affiliation: Universidade Federal do Rio de Janeiro, COPPE/UFRJ, Av. Horácio Macedo, 2030, Bloco G/Sala 206, Centro de Tecnologia, Cidade Universitária, Ilha do Fundão, CEP: 21941-914, Rio de Janeiro, RJ, Brazil.
authors.forename: A P
authors.initials: AP
authors.lastname: Salgado
authors.affiliation: Fundação Técnico Educacional Souza Marques, FTESM, Av. Ernani Cardoso, 335, Cascadura, CEP: 21310-310, Rio de Janeiro, RJ, Brazil.
authors.forename: S P
authors.initials: SP
authors.lastname: Leite
authors.affiliation: Laboratório Nacional de Metrologia das Radiações Ionizantes LNMRI/IRD, Av. Salvador Allende, s/n, Barra da Tijuca, CEP: 22783-127, Rio de Janeiro, RJ, Brazil.
authors.forename: K C S
authors.initials: KC
authors.lastname: Patrão
authors.affiliation: Laboratório Nacional de Metrologia das Radiações Ionizantes LNMRI/IRD, Av. Salvador Allende, s/n, Barra da Tijuca, CEP: 22783-127, Rio de Janeiro, RJ, Brazil.
authors.forename: E S
authors.initials: ES
authors.lastname: Fonseca
authors.affiliation: Fundação Técnico Educacional Souza Marques, FTESM, Av. Ernani Cardoso, 335, Cascadura, CEP: 21310-310, Rio de Janeiro, RJ, Brazil Laboratório Nacional de Metrologia das Radiações Ionizantes LNMRI/IRD, Av. Salvador Allende, s/n, Barra da Tijuca, CEP: 22783-127, Rio de Janeiro, RJ, Brazil.
authors.forename: W W
authors.initials: WW
authors.lastname: Pereira
authors.affiliation: Universidade Federal do Rio de Janeiro, COPPE/UFRJ, Av. Horácio Macedo, 2030, Bloco G/Sala 206, Centro de Tecnologia, Cidade Universitária, Ilha do Fundão, CEP: 21941-914, Rio de Janeiro, RJ, Brazil.
authors.forename: R T
authors.initials: RT
authors.lastname: Lopes
mesh_terms: D000576:Americium; D001608:Beryllium; D001938:Brazil; D002138:Calibration; D002244:Carbon / Q000737:chemistry; D003198:Computer Simulation; D004867:Equipment Design; D006108:Graphite / Q000737:chemistry; D009010:Monte Carlo Method; D009502:Neutrons; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods*; D011839:Radiation, Ionizing; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods*
chemical_list: D002244:Carbon; D006108:Graphite; D001608:Beryllium; D000576:Americium