| 摘要 |
PURPOSE:To enable accurate measurement in wide range of energy region with ease and weighted by providing an ion chamber part charged with gas ionized by the incidence of neutron, an electric source, and a neutron filter. CONSTITUTION:A neutron equivalent dosimeter is loaded on a human body 26. If thermal neutrons 100-1 are irradiated from a neutron filter 14 side, these thermal neutrons 100-1 are absorbed by the filter 14. Thermal neutrons 100-2 pass through the path hole 14a of the filter 14 and slit directly in an ion chamber part 10. The incidence rate of thermal neutrons into the ion chamber part 10 is controlled by controlling the opening area of the path hole 14a. On the other hand, the medium and fast neutrons 200 radiated from the filter 14 side pass through the filter 14 and ion chamber 10 and reach the human body 26. Since the medium and fast neutrons 200 have reaction cross section area for 10B of 1/1000 that of thermal neutrons, they are scattered in the human body 26 and moderated to be thermal neutrons, and so the thermal neutrons 300 scattered in the back go into the ion chamber 10. Therefore, in the ion chamber 10, neutrons 100-2 passing through the path hole 14a and the thermal neutrons 300 scattered in the back are detected.
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