Dark matter search project PICO-LON

14th International Conference on Topics in Astroparticle and Underground Physics

物理学;天文学

Fushimi, K.^1 ; Ejiri, H.^2 ; Hazama, R.^3 ; Ikeda, H.^2 ; Imagawa, K.^4 ; Inoue, K.^4 ; Kanzaki, G.^3 ; Kozlov, A.^6 ; Orito, R.^1 ; Shima, T.^2 ; Takemoto, Y.^5 ; Teraoka, Y.^2 ; Umehara, S.^2 ; Yasuda, K.^5 ; Yoshida, S.^6

Institiute of Socio, Arts and Sciences, Tokushima University, 1-1 Minamijosanjimacho Tokushima city, Tokushima

770-8502, Japan^1

Research Center for Nuclear Physics, Osaka University, 10-1 Mihogaoka, Ibaraki city, Osaka

567-0042, Japan^2

Graduate School and Faculty of Human Environment, Osaka Sangyo University, 3-1-1 Nakagaito, Daito city, Osaka

574-8530, Japan^3

I.S.C. Lab., 7-7-20 Saito Asagi, Ibaraki City, Osaka 567-0085, Japan^4

Kavli Institute for the Physics and Mathematics of the Universe (WPI), University of Tokyo Institutes for Advanced Study, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa city, Chiba

277-8583, Japan^5

Department of Physics, Osaka University, 1-1 Machikaneyama, Toyonaka city, Osaka

560-0043, Japan^6

关键词: Chemical processing;    Cold dark matters;    Dark matter searches;    Future prospects;    Graphite crucibles;    Large volumes;    Lead isotope;    Radioactive impurities;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/718/4/042022/pdf
DOI  :  10.1088/1742-6596/718/4/042022

学科分类：天文学(综合)

来源: IOP

【 摘 要 】

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 of226Ra and228Th 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 of210Pb, which is crucial for the sensitivity to dark matter, was reduced to 24 ± 2 μ Bq/kg. The total background rate at 10 keVeewas 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.