Measurements of Depth Doses by Thermal Neutron and of Neutron Energy Spectra Using Passive Neutron Dosimeter with Spherical Polyethylene Moderator

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  • OGAWA Yoshihiro
    Department of Informatics, School of Science and Engineering, Kinki University

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Other Title
  • 球形ポリエチレン減速材付き中性子線量計を用いた熱中性子深部線量ならびに中性子エネルギースペクトル測定

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Description

To obtain findings about external exposure of neutrons, passive neutron dosimeter with spherical polyethylene moderator having a diameter of 30 cm, in which inserted thermoluminescent elements, as a gammaray detector and gold foils as a neutron detector, was produce. With the neutron dosimeter, measurements of depth doses by thermal neutron and neutron energy spectrum in reactor radiation field at Kinki University Reactor, UTR-KINKI, were carried out.<BR>For measurement of depth doses by thermal neutron, neutron-induced gamma-ray in the (n, γ) reaction with hydrogen was directly measured with BeO thermoluminescent detector and emitted proton in the (n, p) reaction with nitrogen was calculated by using depth thermal neutron flux measured with gold foil activation. As a results, absorbed dose index (DI) for themal neutron incident upon neutron dosimeter was found to be evaluated as DI=1.1 Ds. Where Ds is absorbed dose on surface of neutron dosimeter.<BR>For measurement of neutron energy spectrum, the response matrix of gold foil detectors inside neutorn dosimeter from 10-9 MeV to 20 MeV was made and neutron energy spectrum was estimated with adjustment method using the response matrix and the depth distribution of reading values. As a result, adjusted neutron energy spectrum in reactor radiation field at UTR-KINKI was reproduced for that consisting of 1/E neutron and fission neutron at a good accuracy.<BR>From the results obtained, the present passive neutron dosimeter with spherical polyethylene moderator was found to be useful as a neutron spectrometer and it is shown that accurate neutron doses can be evaluated using adjusted neutron energy spectrum.

Journal

  • RADIOISOTOPES

    RADIOISOTOPES 55 (1), 1-12, 2006

    Japan Radioisotope Association

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