高温超電導SQUIDのガンマ線照射試験 : センサ・計測

概要

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Gamma-ray irradiation tests of High-Tc SQUIDs were carried out to examine their workability in nuclear reactor environments. The SQUIDs were made of a HoBa_2Cu_3O_<7-x> superconductive thin film on SrTiO_3 substrates. Some were encapsulated in separate cases of glass-fiber-rein-forced epoxy resin. Gamma-ray irradiation was performed with a Co-60 gamma-ray source. Irradiation dose rates were (8.1 to 12.2) x 10^3 Gy/h (i.e., (1.0 to 1.5) x 10^6 R/h), and the maximum absorption dose was about 10.4 MGy. During and after irradiation, noises of SQUIDs were measured with a power spectrum analyzer. Changes in modulation voltage were also investigated. No gamma-ray induced noise was observed during irradiation. The noise level and modulation voltage did not change until a total irradiation dose of about 3 MGy, and after that it decreased slightly. We concluded that the tested high-Tc SQUIDs are very resistant to gamma-ray irradiation, and thus the application of high-Tc SQUIDs in inspection of reactor components seems promising.
社団法人日本磁気学会の論文
2002-04-01