{"id":7909,"date":"2025-04-27T13:09:21","date_gmt":"2025-04-27T04:09:21","guid":{"rendered":"https:\/\/www.envraddb.go.jp\/entesttest\/?page_id=7909"},"modified":"2026-06-11T11:38:11","modified_gmt":"2026-06-11T02:38:11","slug":"gamma","status":"publish","type":"page","link":"https:\/\/www.envraddb.go.jp\/en\/special\/tec-info\/gamma\/","title":{"rendered":"\u03b3-ray emitting nuclides"},"content":{"rendered":"
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Overview<\/h2>\r\n <\/div>\r\n
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Measurement principle for \u03b3-ray emitting nuclides(germanium semiconductor detector)<\/h3>\r\n <\/div>\r\n
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\u03b3-ray emitting nuclides are measured indirectly by detecting the high-speed\r\n electrons (secondary electrons) that are produced as a result of the interaction between the incoming \u03b3 rays\r\n (photons) and the detector. \u03b3 rays entering the detector cause various interactions (photoelectric effect,\r\n compton scattering, electron pair production, etc.) to occur. Secondary electrons are produced, and the\r\n ionization effect of these electrons creates electron-hole pairs in the germanium crystal, which act as a\r\n detector by collecting these charges and converting them into electrical signals.<\/p>\r\n <\/div>\r\n

\r\n \"Measurement\r\n <\/figure>\r\n\r\n
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The observed energy spectrum (hereinafter referred to as the \u201cspectrum\u201d)\r\n detected by a \u03b3-ray detector is primarily formed by single or multiple interactions occurring within the\r\n sensitive volume of the detector. However, it also includes contributions from other radiation\u2014such as\r\n scattered \u03b3-rays and X-rays\u2014produced by interactions in surrounding materials, including shielding.\r\n When measuring a sample's \u03b3-ray spectrum, the resulting spectrum is complex due to overlapping energy\r\n distributions produced by the interaction between the \u03b3 rays and the detector, as there are multiple \u03b3 rays\r\n of different energies present. However, only the photoelectric peak (total energy absorption peak) is\r\n analyzed.\r\n \u03b3-ray spectrometry using a germanium semiconductor detector has excellent energy resolution and can\r\n simultaneously quantify multiple nuclides without requiring chemical separation. Of the seven main\r\n nuclides*1<\/sup> in the ALPS-treated\r\n water,134<\/span>Cs,137<\/span>Cs,106<\/span>Ru,60<\/span>Co, and 125<\/span>Sb\r\n have been measured using this method.<\/p>\r\n <\/div>\r\n

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\r\n *1<\/span>Tokyo Electric Power Company Holdings, Inc. Changes to\r\n the operational structure for the release of ALPS-treated water into the ocean and selection of nuclides\r\n for measurement and assessment [Summary]. 2023.\r\n https:\/\/www.nra.go.jp\/data\/0004208F97.pdf<\/a>,(Accessed 2024-10-1)\r\n\r\n <\/p>\r\n <\/div>\r\n <\/div>\r\n\r\n\r\n

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Analysis flow<\/h2>\r\n <\/div>\r\n
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Seawater<\/p>\r\n <\/div>\r\n

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\u2190 Precise analysis of134<\/span>Cs, and\r\n 137<\/span>Cs\r\n <\/p>\r\n <\/div>\r\n

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Sample packing<\/p>\r\n