Understanding internal backgrounds of NaI(Tl) crystals toward a 200~kg array for the KIMS-NaI experiment

P. Adhikari; G. Adhikari; S. Choi; C. Ha; I. S. Hahn; E. J. Jeon; H. W. Joo; W. G. Kang; H. J. Kim; H. O. Kim; K. W. Kim; N. Y. Kim; S. K. Kim; Y. D. Kim; Y. H. Kim; H. S. Lee; J. H. Lee; M. H. Lee; D. S. Leonard; J. Li; S. Y. Oh; S. L. Olsen; H. K. Park; H. S. Park; K. S. Park; J. H. So; Y. S. Yoon

arXiv · 1510.04519

Understanding internal backgrounds of NaI(Tl) crystals toward a 200~kg array for the KIMS-NaI experiment

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Abstract

The Korea Invisible Mass Search (KIMS) collaboration has developed low-background NaI(Tl) crystals that are suitable for the direct detection of WIMP dark matter. With experience built on the KIMS-CsI programs, the KIMS-NaI experiment will consist of a 200~kg NaI(Tl) crystal array surrounded by layers of shielding structures and will be operated at the Yangyang underground laboratory. The goal is to provide an unambiguous test of the DAMA/LIBRA's annual modulation signature. Measurements of six prototype crystals show progress in the reduction of internal contaminations of radioisotopes. Based on our understanding of these measurements, we expect to achieve a background level in the final detector configuration that is less than 1~count/day/keV/kg for recoil energies around 2~keV. The annual modulation sensitivity for the KIMS-NaI experiment shows that an unambiguous 7$\sigma$ test of the DAMA/LIBRA signature would be possible with a 600~kg$\cdot$year exposure with this system.

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P. Adhikari, G. Adhikari, S. Choi, C. Ha, I. S. Hahn, E. J. Jeon, H. W. Joo, W. G. Kang, H. J. Kim, H. O. Kim, K. W. Kim, N. Y. Kim, S. K. Kim, Y. D. Kim, Y. H. Kim, H. S. Lee, J. H. Lee, M. H. Lee, D. S. Leonard, J. Li, S. Y. Oh, S. L. Olsen, H. K. Park, H. S. Park, K. S. Park, J. H. So, Y. S. Yoon. 2015-10-15. Understanding internal backgrounds of NaI(Tl) crystals toward a 200~kg array for the KIMS-NaI experiment. https://arxiv.org/abs/1510.04519

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