Fushimi, Ken-Ichi Tokushima University Tokushima University Educator and Researcher Directory KAKEN Search Researchers
Ejiri, Hiroyasu Osaka University
Hazama, R Osaka Sangyo University
Ikeda, H Tohoku University
Imagawa, K I.S.C. Lab.
Inoue, K Tohoku University
Kanzaki, G Tokushima University
Kozlov, A The University of Tokyo
Orito, Reiko Tokushima University Tokushima University Educator and Researcher Directory KAKEN Search Researchers
Shima, T Osaka University
Takemoto, Y The University of Tokyo
Teraoka, Y Tohoku University
Umehara, S Osaka University
Yasuda, K I.S.C. Lab.
Yoshida, S Osaka University
The PICO-LON project aims at search for cold dark matter by means of highly radio-pure and large volume NaI(Tl) scintillator. The NaI powder was purified by chemical processing to remove lead isotopes and selecting a high purity graphite crucible. The concentrations of radioactive impurities of 226Ra and 228Th were effectively reduced to 58±4 μBq/kg and 1.5±1.9 μBq/kg, respectively. It should be remarked that the concentration of 210Pb, which is crucial for the sensitivity to dark matter, was reduced to 24±2 μBq/kg. The total background rate at 10 keVee was as low as 8 keV-1kg-1day-1, which was sufficiently low to search for dark matter. Further purification of NaI(Tl) ingot and future prospect of PICO-LON project is discussed.
Journal of Physics: Conference Series
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Science and Technology