1. What are underground laboratories used for?
Underground laboratories are research infrastructures built with significant rock overburden to reduce muon flux from primary cosmic rays. They offer new possibilities to search for rare events, such as low energy neutrino interactions, hypothetical dark matter particle interactions, and evidence of neutrinoless double beta decay. Currently, there are 13 underground laboratories in operation worldwide. Besides neutrino physics and astroparticle physics, other fields like earth and environmental science, biology, planetary exploration, geophysics, and gravitational waves observation can benefit from the rock overburden provided by these laboratories. In the last decade, these laboratories have expanded research to neighboring sectors, becoming multi-disciplinary research infrastructures. However, each laboratory has unique features and characteristics that make them suitable for specific activities. For example, Boulby in the UK has low ambient radon levels due to surrounding geology, while Canfranc in Spain and CallioLab in Finland have access to sites at different depths for varying muon background levels. SNOlab in Canada and JingPing in China are very deep, resulting in a significant reduction of locally muon-induced background. Overall, underground laboratories play a crucial role in advancing research in various scientific fields.
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2. What are the key facilities provided by underground laboratories for rare events research?
Underground laboratories offer specialized equipment for radio-purity assay, including 76 high-purity germanium detectors for gamma spectroscopy, high sensitivity radon detectors, beta and alpha spectrometers. They also provide advanced technologies such as radon-free clean rooms, massive production of high radio-purity copper electro-formed, cryogenic detectors, additive manufacturing, and innovative photo-detectors based on SiPM. These facilities are crucial for assembling dark matter detectors and pushing the sensitivity of instruments for dark matter and neutrinoless double beta decay research.
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3. What will CJPL-II become in 2024?
CJPL-II, with an excavated volume of 300k m 3, will transform into a Deep Underground and ultra-low Radiation background Facility for frontier physics experiments (DURF) in 2024. DURF will be equipped with a crystal and copper electro-forming production facility, an assay radio-purity facility, and shielding infrastructures made of water and liquid nitrogen to host next-generation experiments. This facility will provide a unique environment for conducting cutting-edge physics research with minimal background interference.
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