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Rn-reduced air - electrostatic

Rn-reduced air - electrostatic. Rn-reduced air systems on KamLAND. Masayuki Koga RCNS Tohoku Univ. KamLAND site KamLAND have many experimental rooms and huge air volume. dome area : ~300m 3 purification area : ~1000m 3

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Rn-reduced air - electrostatic

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  1. Rn-reduced air - electrostatic Rn-reduced air systems on KamLAND Masayuki Koga RCNS Tohoku Univ.

  2. KamLAND site KamLAND have many experimental rooms and huge air volume. dome area : ~300m3 purification area : ~1000m3 control room, Ge detector room, valves station , etc… Dorm area Control room KamLAND Valves station Ge detector hat Purification area for oils These areas should be keep low Rn concentration ! LRT2004 Masayuki Koga

  3. What kind of the Rn-reduced air system is better for large and sensitive detector? • Rn concentration in the mine air is too high • Spaces are limited in the mine • We need large volume Rn-reduced air supply system . • Access points to the detector should be very low Rn concentration (ex. chimney area on KamLAND) • Purge gas for inside of detector should be used noble gas (we use N2 gas) • Each rooms should be coated by the mine gard (a kind of polyurethane resin) • low cost ! => We cannot choice special method LRT2004 Masayuki Koga

  4. Environment Rn concentration in the kamioka mine Seasonal variation of Rn concentration in the mine Summer Summer : 2500 – 3500Bq/m3 Winter : 200 – 300Bq/m3 Winter @KamLAND site LRT2004 Masayuki Koga

  5. Rn-reduced air supply system ① Flesh air supply from outside of the mine 20-30Bq/m3 1000m3/h to KamLAND (30cmφ, 30m) expected Rn concentration <50Bq/m3 20cmφ polyethylene pipe LRT2004 Masayuki Koga

  6. Rn-reduced air supply system ②Rn-reduced air using a cooled activated charcoal Rn trap Radon trap dorm area cooler -45℃ 100m3/h Rn: 10-20mBq/m3 heat insulator N2 gas generator (used under oil filling) clean and dry air supply methyl alcohol 300 ℓ 3m3 cooled activated charcoal LRT2004 Masayuki Koga

  7. Flesh air from outside Rn-less N2 gas KamLAND Rn-reduced air and N2 gas systems Glove box clean room dorm area chimney clean room 100-200m3/h each Rn-reduced air from the cooled charcoal trap 30m3/h each preparation clean room for calibration 4l/min to chimney (2l/min to glove box) purification area Ge detector hat, etc… LRT2004 Masayuki Koga

  8. Achieved Rn concentration LRT2004 Masayuki Koga

  9. summary • We prepared 2 type Rn-reduced air systems • Achieved Rn concentration dorm area, purification area : 20-30 Bq/m3 clean room for chimney, glove box: 1-2 Bq/m3 • We need more progress against 7Be neutrino detection *Thanks for Super-Kamiokande group We borrowed sensitive Rn detectors LRT2004 Masayuki Koga

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