Calibration of a neutron dose rate meter in various neutron standard fields

This paper presents the calibration of a neutron dose rate meter and the evaluation of its calibration factors (CFs) in several neutron standard fields (i.e., two standard fields with bare sources of 252Cf\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{252}\hbox {Cf}$$\end{document} and 241Am-Be\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{241}\hbox {Am}{-}\hbox {Be}$$\end{document}, and five simulated workplace fields with 241Am-Be\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{241}\hbox {Am}{-}\hbox {Be}$$\end{document} moderated sources). The calibration in standard fields with bare sources was conducted by following the recommendations of the ISO 8529 standard. The measured total neutron ambient dose equivalent rates, denoted as H∗˙(10)tot\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{H^*}(10)_{\text {tot}}$$\end{document}, were analyzed to obtain direct components, denoted as H∗˙(10)dir\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{H^*}(10)_{\text {dir}}$$\end{document}, using a reduced fitting method. The CF was then calculated as the ratio between the conventional true value of the neutron ambient dose equivalent rate in a free field, denoted as H∗˙(10)FF\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{H^*}(10)_{\text {FF}}$$\end{document}, and the value of H∗˙(10)dir\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{H^*}(10)_{\text {dir}}$$\end{document}. In contrast, in the simulated workplace neutron fields, the calibration of the neutron dose rate meter was conducted by following the ISO 12789 standard. The CF was calculated as the ratio between the values of H∗˙(10)tot\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{H^*}(10)_{\text {tot}}$$\end{document} measured by a standard instrument (i.e., Bonner sphere spectrometer) and the neutron dose rate meter. The CF values were obtained in the range of 0.88–1.0. The standard uncertainties (k=1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$k = 1$$\end{document}) of the CFs were determined to be in the range of approximately 6.6–13.1%.