Particle Physics Group,Department of Physics, Graduate School of Science, Kobe University

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Research topics

Development of high-sensitive radon detection techniques

Radon (or Rn-222) is a radioactive noble gas with 3.8 days half-life. Rn-222 even exists in normal outdoor air, and its typical concentration is 1-10 Bq/m3 (Becquerel per cubic meter). The radon concentration may become higher in the underground caverns. For example, in Kamioka underground observatory, the radon concentration reaches at about 1000Bq/m3. There are many daughter nucleus of Rn-222. For example, beta decay of Bi-214 has 3.27 MeV maximum energy . So, if radon contaminate in a detector, it will become a background source in MeV energy region in the detector. In the underground site, significant amount of the cosmic ray could be reduced. But, since radon concentration may become high, the monitoring and protection against radon will be necessary. Such technique is a common important topic in low-energy physics experiments in the world. In recent years, the exchange of information and technology are actively done among researchers in the world.

Our group has developed a real-time Rn-222 detector which has a sensitivity of mBq/m3 level in pure water and in the air. We have been applied the detector to search for the possible radon source in the Super-Kamiokande experiment. This radon detector and/or similar detector based on the detector have been used by several domestic and international research groups in the low-energy physics experimental projects.

Currently, we are developing a detection technique to measure residual radon in purified noble gases. So far, we have developed the technique to measure micro Bq/m3 level radon in purified argon gas. We are going to develop a precise radon monitoring and reduction techniques in purified xenon gas.

Publications, conference talks

  • “気体アルゴン中ラドンの吸着脱離実験と極低レベルラドン濃度測定方法の開発”, RADIOISOTOPES,59 (2010) 29-36,池田一得、外間智規、田阪茂樹、竹内康雄
  • "Development of Super-high Sensitivity Radon Detector for the Super-Kamiokande Detector" Nucl. Instr. and Meth. A497 (2003) 414-428 C.Mitsuda, T.Kajita, K.Miyano, S.Moriyama, M.Nakahata, Y.Takeuchi, and S.Tasaka
  • "Radon reduction and monitoring in Super-Kamiokande" Radon background in rare-event experiments workshop, Sudbury, June 14, 2000
  • "Radon background in the Super-Kamiokande" Poster presentation at NEUTRINO'98, Takayama, June, 1998
  • "Measurement of radon concentrations at Super-Kamiokande" Phys. Lett. B452 (1999) 418-424 The Super-Kamiokande Collaboration, Y.Takeuchi et al.
  • "Development of high sensitivity radon detectors" Nucl. Instr. and Meth. A421 (1999) 334-341 Y.Takeuchi, K.Okumura, T.Kajita, S.Tasaka, H.Hori, M.Nemoto and H.Okazawa
  • "スーパーカミオカンデでのラドン測定" 日本物理学会1998年秋の分科会(秋田大学)、1998年10月
  • "Super-Kamiokandeでの太陽ニュートリノ観測とラドン測定" 極低放射能バックグラウンド環境下における科学とその展望ワークショップ (大阪大学核物理研究センター)、1998年3月
  • "Development and calibration of a high sensitive radon detector in air" Poster presentation at The 7th Tohwa University International Symposium, October 1997 M.Nemoto, S.Tasaka, H.Hori, K.Okumura, T.Kajita, Y.Takeuchi, and H.Okazawa



  • Yasuo Takeuchi

Related researches


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  • Kobe University
  • Graduate School of Science, Kobe University
  • Physics Department,Graduate School of Science, Kobe University