New thermal neutron calibration channel at LNMRI/IRD

8th Brazilian Congress on Metrology

Astuto, A.^1,2 ; Patrão, K.C.S.^3 ; Fonseca, E.S.^3 ; Pereira, W.W.^2,3 ; Lopes, R.T.^1

Universidade Federal Do Rio de Janeiro - COPPE/UFRJ, Centro de Tecnologia - Cidade Universitária, Av. Horácio Macedo, 2030, Bloco G/Sala 206, Ilha do Fundão, Rio de Janeiro

RJ

CEP: 21941-914, Brazil^1

Fundação Técnico Educacional Souza Marques - FTESM, Av. Ernani Cardoso, 335, Cascadura, Rio de Janeiro

RJ

CEP: 21310-310, Brazil^2

Laboratório Nacional de Metrologia das Radiações Ionizantes LNMRI/IRD, Av. Salvador Allende, s/n, Barra da Tijuca, Rio de Janeiro

RJ

CEP: 22783-127, Brazil^3

关键词: Fluences;    Front face;    MCNPX code;    Neutron fluences;    Neutron metrology;    Thermal neutrons;    Thermal-neutron flux;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/733/1/012080/pdf
DOI  :  10.1088/1742-6596/733/1/012080

来源: IOP

【 摘 要 】

A new standard thermal neutron flux unit was designed in the National Ionizing Radiation Metrology Laboratory (LNMRI) for calibration of neutron detectors. Fluence is achieved by moderation of four241Am-Be sources with 0.6 TBq each, in a facility built with graphite and paraffin blocks. The study was divided into two stages. First, simulations were performed using MCNPX code in different geometric arrangements, seeking the best performance in terms of fluence and their uncertainties. Last, the system was assembled based on the results obtained on the simulations. The simulation results indicate quasi-homogeneous fluence in the central chamber and H∗(10) at 50 cm from the front face with the polyethylene filter.