He 集積法による中性子照射量測定のための He 絶対量測定装置

Abstract

In the helium accumulation method for neutron dosimetry, it is applied that the number of helium atoms produced through (n,xα) reaction is proportional to neutron fluence in fast neutron irradiation fields. Besides, activities measuring in the activation method saturate to the value depending on their half-lives. A helium atom measurement, system for detecting of helium atoms accumulated in neutron-irradiated samples has been constructed and tested. The samples are vaporized in a furnace to release helium contained in them. The number of helium atoms is measured with a quadrupole mass spectrometer calibrated by a standard helium gas supply which is consist of a known-volume vessel, a pressure gauge and a thermometer. It has been proposed in this work that helium-ion implanted aluminum disks are applied to calibrate the helium atom measurement system. This method has succeeded to obtain results agreed with the standard helium gas supply system.