Development of ultra-pure NaI(Tl) detectors for the COSINE-200 experiment

B. J. Park; J. J. Choi; J. S. Choe; O. Gileva; C. Ha; A. Iltis; E. J. Jeon; D. Y. Kim; K. W. Kim; S. K. Kim; Y. D. Kim; Y. J. Ko; C. H. Lee; H. S. Lee; I. S. Lee; M. H. Lee; S. H. Lee; S. J. Ra; J. K. Son; K. A. Shin

doi:10.1140/epjc/s10052-020-8386-8

2021 Impact factor 4.991

Particles and Fields

Open Access

Eur. Phys. J. C (2020) 80: 814
https://doi.org/10.1140/epjc/s10052-020-8386-8

Regular Article - Experimental Physics

Development of ultra-pure NaI(Tl) detectors for the COSINE-200 experiment

B. J. Park¹^,2, J. J. Choi³, J. S. Choe², O. Gileva², C. Ha⁴^e, A. Iltis⁵, E. J. Jeon², D. Y. Kim², K. W. Kim², S. K. Kim³, Y. D. Kim¹^,2, Y. J. Ko², C. H. Lee², H. S. Lee¹^,2^q, I. S. Lee², M. H. Lee¹^,2, S. H. Lee¹^,2, S. J. Ra², J. K. Son² and K. A. Shin²

¹ IBS School, University of Science and Technology (UST), 34113, Daejeon, Republic of Korea
² Center for Underground Physics, Institute for Basic Science (IBS), 34126, Daejeon, Republic of Korea
³ Department of Physics and Astronomy, Seoul National University, 08826, Seoul, Republic of Korea
⁴ Department of Physics, Chung-Ang University, 06973, Seoul, Republic of Korea
⁵ Damavan Imaging, 10430, Troyes, France

^e changhyon.ha@gmail.com
^q hyunsulee@ibs.re.kr

Received: 14 April 2020
Accepted: 24 August 2020
Published online: 2 September 2020

Abstract

The annual modulation signal observed by the DAMA experiment is a long-standing question in the community of dark matter direct detection. This necessitates an independent verification of its existence using the same detection technique. The COSINE-100 experiment has been operating with 106 kg of low-background NaI(Tl) detectors providing interesting checks on the DAMA signal. However, due to higher backgrounds in the NaI(Tl) crystals used in COSINE-100 relative to those used for DAMA, it was difficult to reach final conclusions. Since the start of COSINE-100 data taking in 2016, we also have initiated a program to develop ultra-pure NaI(Tl) crystals for COSINE-200, the next phase of the experiment. The program includes efforts of raw powder purification, ultra-pure NaI(Tl) crystal growth, and detector assembly techniques. After extensive research and development of NaI(Tl) crystal growth, we have successfully grown a few small-size (0.61–0.78 kg) thallium-doped crystals with high radio-purity. A high light yield has been achieved by improvements of our detector assembly technique. Here we report the ultra-pure NaI(Tl) detector developments at the Institute for Basic Science, Korea. The technique developed here will be applied to the production of NaI(Tl) detectors for the COSINE-200 experiment.

© The Author(s) 2020

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