2026-03-15T05:48:51Z https://kanazawa-u.repo.nii.ac.jp/oai

oai:kanazawa-u.repo.nii.ac.jp:00064325 2024-06-25T06:36:47Z 1979:1982:1983:4286

金沢城鉛瓦と低バックグラウンドγ線測定 Lead Roof Tiles from Kanazawa Castle and Low-background γ-spectrometry INOUE, Mutsuo 60283090 井上, 睦夫 金沢城 鉛瓦 鉛-210 γ線測定 Kanazawa Castle lead tile 210Pb γ-spectrometry The use of lead in the roof tiles in the construction of Kanazawa Castle was a unique feature among the castles of Japan. This was done for the purposes of creating a more beautiful appearance, for the storage of surplus lead, for material for bullets in wartime, for reducing the weight of the roof, and so forth. The roof tiles bestow a quaint and whitish appearance to the castle as a result of the passing of time. The castle site was used as the main campus for Kanazawa University following its use as an army base until the end of World War II. When the university moved its campus to another location, the area was converted into a castle park with a beautifully restored castle. The used and depleted 210Pb (half-life, 22.3 years) lead tiles from the castle buildings have been found to serve as important shield materials for Ge detectors used in γ-spectrometry. The Low Level Radioactivity Laboratory at Kanazawa University prepared hand-made shields using castle lead that was discarded during the demolition of the castle buildings. In co-operation with the Ogoya Underground Laboratory (270-meter-thick water equivalent), these lead shields reduced the counting rates of Ge detectors notably to ~1/100 of ground levels, which corresponded to an improvement of ~1/10 of the detection limit for low-level radionuclides. In a period of twenty-eight years since 1995, significant research has been conducted using Ge detectors to study geochemistry and radioactive contamination. One notable example included measuring the oceanwide diffusion of low-level radiocesium, which escaped from the Fukushima Dai-ichi Nuclear Power Plant following its flooding during the March 2011 earthquake and tsunami disaster in the Tohoku region of northeastern Japan. 2023-03-17 金沢大学環日本海域環境研究センター Institute of Nature and Environmental Technology Kanazawa University 2023-03-17 2023-06-30 jpn departmental bulletin paper VoR https://doi.org/10.24517/00070552 http://hdl.handle.net/2297/00070552 https://kanazawa-u.repo.nii.ac.jp/records/64325 10.24517/00070552 AA11430153 1347-7889 日本海域研究 Japan sea research 54 61 68 https://kanazawa-u.repo.nii.ac.jp/record/64325/files/AA11430153-54-61-68.pdf application/pdf 1.4 MB 2023-06-30