| 摘要 |
PURPOSE:To detect 1 cm dose equivalent at high accuracy by arranging first collecting electrodes comprising a material whose effective atomic number is lower than 8 and second collecting electrodes comprising metal in ionization chambers wherein the inner wall which transmit radiation of 10 keB or more is provided. CONSTITUTION:The thickness of the case 1 is selected at a degree so that gamma rays of 10 keV or more can be transmitted. A secondary-electron- shielding inner wall 3 provided at the inner surface of the case 1 has the thickness at a degree so that the secondary electrons from the case 1 can be shielded. The inner wall 3 is formed with a material whose effective atomic number is low. Conductor layers 31 comprising conductive paint whose effective atomic number is low are formed on the surface of first collecting electrodes 20 and 20 which are arranged in ionization chambers 11 and 15. Second collecting electrodes 21, 21...21 comprising metal are arranged in ionization chambers 10, 12, 13, 14 and 16. Under the state wherein said ionization chambers are attached to a dammy body made of macromolecular material for calibrating 1 cm dose equivalent, the gamma rays are projected.
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