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

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.

12 pages, 12 figures

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• Performance of a prototype active veto system using liquid scintillator for a dark matter search experiment
• Growth of Ultra-high Purity NaI(Tl) Crystal for Dark Matter Searches
• A facility for mass production of ultra-pure NaI powder for the COSINE-200 experiment

Cited by in corpus (16)

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• Scintillation characteristics of a NaI(Tl) crystal at low-temperature with silicon photomultiplier
• Search for Boosted Dark Matter in COSINE-100
• Performance of an ultra-pure NaI(Tl) detector produced by an indigenously-developed purification method and crystal growth for the COSINE-200 experiment
• Sensitivities for coherent elastic scattering of solar and supernova neutrinos with future NaI(Tl) dark matter search detectors of COSINE-200/1T
• Study on NaI(Tl) crystal at -35 C for dark matter detection
• Search for solar bosonic dark matter annual modulation with COSINE-100
• Search for inelastic WIMP-iodine scattering with COSINE-100
• The role of small scale experiments in the direct detection of dark matter
• Scintillation characteristics of an undoped CsI crystal at low-temperature for dark matter search
• Searching for low-mass dark matter via Migdal effect in COSINE-100
• Identification of new isomers in ${}^{228}$Ac : Impact on dark matter searches
• Background stability and annual modulation test using PICOLON ultra-pure NaI(Tl) detector
• Constraints on sub-GeV dark matter scattering on electrons with COSINE-100