Understanding internal backgrounds in 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

doi:10.1140/epjc/s10052-016-4030-z

2022 Impact factor 4.4

Particles and Fields

Open Access

Eur. Phys. J. C (2016) 76: 185
https://doi.org/10.1140/epjc/s10052-016-4030-z

Regular Article - Experimental Physics

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

P. Adhikari¹, G. Adhikari¹, S. Choi², C. Ha³^*, I. S. Hahn⁴, E. J. Jeon³, H. W. Joo², W. G. Kang³, H. J. Kim⁵, H. O. Kim³, K. W. Kim², N. Y. Kim³, S. K. Kim², Y. D. Kim¹^,3, Y. H. Kim³^,6, H. S. Lee³^**, J. H. Lee³, M. H. Lee³, D. S. Leonard³, J. Li³, S. Y. Oh¹, S. L. Olsen³, H. K. Park³, H. S. Park⁶, K. S. Park³, J. H. So³ and Y. S. Yoon³

¹ Department of Physics, Sejong University, Seoul, 05006, Korea
² Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Korea
³ Center for Underground Physics, Institute for Basic Science, Daejeon, 34047, Korea
⁴ Department of Science Education, Ewha Womans University, Seoul, 03760, Korea
⁵ Department of Physics, Kyungpook National University, Daegu, 41566, Korea
⁶ Korea Research Institute of Standards and Science, Daejeon, 34113, Korea

^* e-mail: changhyon.ha@gmail.com
^** e-mail: hyunsulee@ibs.re.kr

Received: 28 January 2016
Accepted: 17 March 2016
Published online: 6 April 2016

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. Building on experience accumulated during 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 annual modulation signature. Measurements of six prototype crystals show progress in the reduction of internal contamination from 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 test of the DAMA/LIBRA signature would be possible with a 600 kg year exposure with this system.