Dark matter search project PICO-LON. Issue 4 (May 2016)

• Record Type: Journal Article
• Authors: Fushimi, K; Ejiri, H; Hazama, R; Ikeda, H; Imagawa, K; Inoue, K; Kanzaki, G; Kozlov, A; Orito, R; Shima, T; Takemoto, Y; Teraoka, Y; Umehara, S; Yasuda, K; Yoshida, S
• Other Names: collab.
• Is Part Of: Journal of physics. Volume 718:Issue 4(2016)
• Publication Date: 2016-05
• Subjects: Physics -- Congresses; 530.5
• DOI: 10.1088/1742-6596/718/4/042022
• Languages: English
• ISSNs: 1742-6588

Abstract

Abstract: 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 226 Ra and 228 Th were effectively reduced to 58 ± 4 µ Bq/kg and 1.5 ± 1.9 µ Bq/kg, respectively. It should be remarked that the concentration of 210 Pb, which is crucial for the sensitivity to dark matter, was reduced to 24 ± 2 µ Bq/kg. The total background rate at 10 keVee was as low as 8 keV −1 kg −1 day −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.