The COSINE experiment is searching for dark matter using ultra-low background NaI scintillating crystals. In order to reduce the internal contamination of the initial NaI powder to grow NaI crystals, NaI powder samples with different purities were purified by fractional recrystallization using de-ionized water. The concentrations of the main radioactive elements, K, Pb, Th, and U, which are major backgrounds for the dark matter search, were reduced to the level required for the experiment. Further, the concentrations of other impurities, e.g., Ba, Ca, Cr, and Fe, were also reduced, which is important to realize good quality NaI crystals.
Dark matter Fractional recrystallization Radioactive impurity Ultralow-background NaI crystal
This is a preview of subscription content, log in to check access.
We thank J.S. Choi for ICP-MS measurements. This research was funded by the Institute for Basic Science (Korea) Under Project Code IBS-R016- A1. HyangKyu Park was supported by a Korea University Grant.
Rubin VC, Thonnard N, Ford WK (1980) Rotational properties of 21 SC galaxies with a large range of luminosities and radii, from NGC 4605 (R = 4 kpc) to UGC 2885 (R = 122 kpc). Astrophys J 238:471–487CrossRefGoogle Scholar
Blumenthal GR, Faber SM, Primack JR, Reses MJ (1984) Formation of galaxies and large-scale structure with cold dark matter. Nature 311:517–525CrossRefGoogle Scholar
Begeman KG, Broeils AH, Sanders RH (1991) Extended rotation curves of spiral galaxies: dark haloes and modified dynamics. Mon Not Roy Astron Soc 249:523–536CrossRefGoogle Scholar
Bertone G, Hooper D, Silk J (2005) Particle dark matter: evidence, candidates and constraints. Phys Rep 405:279–390CrossRefGoogle Scholar
Jungman G, Kamionkowski M, Griest K (1996) Supersymmetric dark matter. Phys Rep 267:195–373CrossRefGoogle Scholar
Bernabei R et al (2008) The DAMA/LIBRA apparatus. Nucl Instrum Methods Phys Res A 592(3):297–315CrossRefGoogle Scholar
Johnson JR (1965) The direct synthesis and purification of sodium iodide. Retrospective Theses and Dissertations 3359, Iowa State University of Science and Technology Ames, Iowa http://lib.dr.iastate.edu/rtd/3359