Regular Article - Experimental Physics
Development of ultra-pure NaI(Tl) detectors for the COSINE-200 experiment
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
Accepted: 24 August 2020
Published online: 2 September 2020
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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