Core Insights - The Jiangmen Underground Neutrino Observatory (JUNO) has successfully completed the infusion of 20,000 tons of liquid scintillator and has officially begun data collection, marking a significant milestone in neutrino research [5][9] - This facility is the first large-scale, high-precision neutrino detector in the world, aimed at addressing major questions in particle physics, particularly the mass ordering of neutrinos [5][6] Project Overview - The JUNO project was proposed by the Institute of High Energy Physics of the Chinese Academy of Sciences in 2008, receiving support from the Chinese Academy of Sciences and the Guangdong provincial government [8] - Construction began in 2015, with the laboratory completed in December 2021, and the detector's main construction expected to be finished by December 2024 [8] Technical Achievements - The core detector has an effective mass of 20,000 tons and is located 700 meters underground, allowing it to detect neutrinos from nearby nuclear power plants with unprecedented precision [6][9] - The detector's construction involved the infusion of over 60,000 tons of ultra-pure water within 45 days, ensuring safety and stability [8] International Collaboration - The JUNO project involves 700 researchers from 17 countries and regions, highlighting significant international collaboration in advancing neutrino detection technology [9] - The project is expected to have a lifespan of 30 years, with potential upgrades to enhance its capabilities for future experiments [9]

Core Viewpoint - The Jiangmen Underground Neutrino Observatory (JUNO) has successfully completed the infusion of 20,000 tons of liquid scintillator and has officially begun data collection, aiming to address significant issues in particle physics over the next decade, particularly the mass ordering of neutrinos [1]. Group 1 - The JUNO detector is located 700 meters underground near Jiangmen, Guangdong, and can detect neutrinos from the Taishan and Yangjiang nuclear power plants located 53 kilometers away, measuring their energy spectrum with unprecedented precision [2]. - Compared to international counterparts, JUNO's measurement of mass ordering is unaffected by terrestrial material effects and other unknown neutrino oscillation parameters, significantly improving the precision of three out of six neutrino oscillation parameters [2]. - The experiment will enable cutting-edge research on neutrinos from various sources, including the sun, supernovae, atmosphere, and Earth, and will open new avenues for exploring unknown physics, including searches for sterile neutrinos and proton decay [2]. Group 2 - The core detector of JUNO is a 20,000-ton liquid scintillator detector, situated in a 44-meter deep water pool, supported by a 41.1-meter diameter stainless steel mesh shell, housing numerous critical components including a 35.4-meter diameter acrylic sphere and thousands of photomultiplier tubes [4]. - The photomultiplier tubes work in unison to detect scintillation light produced by neutrino interactions with the liquid scintillator, converting it into electrical signals for output [4][6]. - JUNO is designed for a lifespan of 30 years and can later be upgraded to become the world's most sensitive experiment for neutrinoless double beta decay, which will probe the absolute mass of neutrinos and test whether they are Majorana particles, addressing key challenges in particle physics, astrophysics, and cosmology [7].

Core Viewpoint - The Jiangmen Neutrino Experiment (JUNO) has successfully completed the infusion of 20,000 tons of liquid scintillator and has officially begun data collection, marking it as the first operational large-scale and high-precision neutrino-specific scientific facility in the world [1][10]. Group 1: Experiment Overview - The JUNO detector is located 700 meters underground near Jiangmen, Guangdong Province, and can detect neutrinos produced by the Taishan and Yangjiang nuclear power plants, measuring their energy spectrum with unprecedented precision [3]. - The experiment aims to address a significant issue in particle physics over the next decade: the ordering of neutrino masses, and will assist scientists in conducting cutting-edge research on neutrinos from the sun, supernovae, atmosphere, and Earth [1][9]. Group 2: Construction and Technical Details - The JUNO project was proposed by the Institute of High Energy Physics, Chinese Academy of Sciences in 2008, received support in 2013, and began construction in 2015. The laboratory was completed in December 2021, with the detector installation starting thereafter [5]. - The infusion process involved over 60,000 tons of ultra-pure water completed in 45 days, with strict control over liquid levels and flow deviations, ensuring the safety and stability of the detector structure [5]. - The core detector, with an effective mass of 20,000 tons, is housed in a 44-meter deep pool and consists of a 35.4-meter diameter acrylic sphere, 20,000 20-inch photomultiplier tubes, and 25,000 3-inch photomultiplier tubes [7]. Group 3: Future Prospects - The JUNO experiment is a major international collaboration involving nearly 700 researchers from 74 institutions across 17 countries and regions, with a design lifespan of 30 years [9]. - Future upgrades could transform JUNO into the world's most sensitive experiment for neutrinoless double beta decay, potentially answering fundamental questions about the nature of neutrinos and the universe [9].