China has made a significant leap in its quest to unravel the mysteries of the universe with the Jiangmen Underground Neutrino Observatory (JUNO). On Wednesday, the team began filling the world's largest transparent spherical detector with ultrapure water, marking the final critical stage of the project.
The JUNO facility, spearheaded by the Institute of High Energy Physics under the Chinese Academy of Sciences, features a 44-meter-deep cylindrical pool nestled in the granite layers of Kaiping, Jiangmen City. This state-of-the-art detector is supported by a robust stainless steel mesh shell and an acrylic sphere designed to hold 20,000 tonnes of liquid scintillator.
Equipped with an impressive array of 20,000 20-inch photomultiplier tubes and 25,000 3-inch photomultiplier tubes, JUNO is poised to achieve unprecedented levels of energy resolution and photoelectron yield. These advanced components work in tandem to capture the elusive neutrinos, often dubbed \"ghost particles\" due to their ability to pass through matter undetected.
The filling process involves two stages: first, the detector pool and acrylic sphere are filled with ultrapure water over two months, followed by replacing the water with liquid scintillator over six months. Completion of this process is slated for August 2025, after which JUNO will commence formal operations and data collection.
Neutrinos play a crucial role in our understanding of cosmic phenomena, from supernova explosions to the inner workings of stars. JUNO's primary scientific goal is to measure the neutrino mass hierarchy, a key piece in the puzzle of particle physics and cosmology. With a diverse team of over 700 members from 17 countries and regions, JUNO is set to become a cornerstone of international neutrino research, alongside other major projects like Japan's Hyper-Kamiokande and the United States' Deep Underground Neutrino Experiment.
As JUNO progresses towards its completion, it promises to open new avenues for scientific discovery, fostering global collaboration and pushing the boundaries of our knowledge about the fundamental particles that shape our universe.
Reference(s):
China's transparent spherical neutrino detector reaches critical stage
cgtn.com
