Jiangmen Underground Neutrino Observatory (JUNO) has now entered its final construction phase, according to the Institute of High Energy Physics at the Chinese Academy of Sciences.

The innermost acrylic sphere has been fully assembled, and the outer stainless-steel grid and photomultiplier tubes are also coming together smoothly, with all installation tasks expected to be completed by the end of November. JUNO's primary scientific goal is to determine the neutrino mass hierarchy, along with other major cutting-edge research. Upon completion, it will become one of the key centers for international neutrino research.

JUNO's core detector is located approximately 700 meters underground. It includes the world's largest single acrylic sphere, a 20,000-tonne liquid scintillator used to detect neutrinos, and 45,000 photomultiplier tubes. The acrylic sphere will need to withstand a buoyant force of around 3,000 tonnes over long-term operation.

Additionally, the team has overcome several key technical challenges, such as developing photomultiplier tubes with the highest photon detection efficiency globally. They have also developed a high-purity, high-seal and high-efficiency purification system for the liquid scintillator, achieving the world's longest attenuation length to date.

Once completed, JUNO will stand alongside Japan's Super-Kamiokande and the United States' Deep Underground Neutrino Experiment, solidifying China's leading position in the field of neutrino research.