Parameter of Neutron Calibration Field in Viet Nam

This paper presents the technical parameters of neutron calibration fields available in Viet Nam for calibrations of neutron measuring meters (i.e., neutron ambient dose equivalent/rate meters and/or neutron personal dose equivalent/rate meters - referred to neutron meters). The mentioned technical parameters of neutron calibration fields, in this work, consist of physical quantity (i.e., the integrated neutron fluence rate over a neutron spectrum, ϕ); operational dosimetric quantities (i.e., ambient dose equivalent rate,˙H∗(10)); and radiation quantities (i.e., fluence-spectrum-averaged energies, E; fluence-to-ambient dose equivalent conversion coefficient, h∗). The technical parameters of neutron reference fields were reported for different radiation beam qualities (i.e., for direct neutron component from a neutron reference fields of a bare 241Am-Be, complied with the ISO-8529 series criteria; and for total neutron component from simulated workplace neutron reference fields of a 241Am-Be source moderated by different polyethylene spheres and from a neutron reference field of a bare 239Pu-Be source, complied with the ISO-12789 series criteria). The technical parameters of the SO-8529 neutron reference field of the bare 241Am-Be source were theoretically calculated based on the total neutron source strength and presented for direct neutron component. In addition, the technical parameters of the ISO-12789 simulated workplace neutron reference fields of the 241 Am-Be source moderated by different polyethylene spheres as well as of the 239Pu-Be source were characterized using the Bonner sphere spectrometer system accompanying with the FRUIT neutron spectrum unfolding code for the total neutron component. The technical parameters as well as their standard combined uncertainties of neutron fields were also presented in conjunction with different distances from the sources’ centers.