Speaker
Dr
Hiroyuki Sekiya
(ICRR, University of Tokyo)
Description
This presentation is for the lowest energy physics in Super-Kamiokande, solar neutrino. SK detects 8B solar neutrinos through neutrino-electron elastic scattering, where the energy, direction, and time of the recoil electron are measured. Since SK-III started, many efforts to reduce backgrounds have been made. The most serious background comes from the beta decay of 214Bi, which is produced in the decays of radon in the purified air, detector materials, and the purified water. In order to reduce the 214Bi background, the SK water system has been upgraded. First, the cooling power of the heat exchanger for the supply water was increased so as not to induce convection in the tank, which transports radon near the PMTs into the fiducial volume. Then, the water flow in the detector was precisely investigated and optimized to reduce the background contamination in the fiducial volume as much as possible. In order to evaluate the remaining radon concentration, very low background and high precision radon detectors for air and water were newly developed. Not only radon, but other contaminations in the water (bacteria and metal ion) were also investigated.
Primary author
Dr
Hiroyuki Sekiya
(ICRR, University of Tokyo)
