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Title: Quest for the lowest-energy neutrinos in Super-Kamiokande

Super-Kamiokande (SK) has been observing {sup 8}B solar neutrinos for 17 years. Since the start of the SK-III phase, much effort has been expended in reducing backgrounds. The main contributing background comes from the beta decay of {sup 214}Bi, which is produced in the decays of radon in the purified air, detector materials, and the purified water. To reduce this background, the water system of SK has been upgraded. Heat exchangers for the cooling supply water were improved so as to suppress convection in the tank that transports radon near the photomultiplier tubes into the fiducial volume. To evaluate the remaining radon concentration, very-low-background radon detectors for air and water were designed and developed. Not only radon, but other contaminants in the water (bacteria and metal ions) were also investigated.
Authors:
 [1]
  1. Kamioka Observatory, Institute for Cosmic Ray Research, The University of Tokyo, Higashi-Mozumi, Kamioka, Hida, Gifu 506-1205 (Japan)
Publication Date:
OSTI Identifier:
22488713
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1672; Journal Issue: 1; Conference: LRT 2015: 5. international workshop in low radioactivity techniques, Seattle, WA (United States), 18-20 Mar 2015; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; BETA DECAY; BISMUTH 214; BORON 8; CONCENTRATION RATIO; CONVECTION; COOLING; HEAT EXCHANGERS; NEUTRINO DETECTION; RADON; RADON ISOTOPES; SOLAR NEUTRINOS; WATER