JUNO Project in China: The Hunt for Neutrino Mass

In the deep regions of the southern Chinese province of Guangdong, the mega-project of the Jiangmen Underground Neutrino Observatory (JUNO) is progressing. A giant sphere, equipped with countless light-sensitive tubes, will soon be used for experiments to study the elusive subatomic particles known as neutrinos. This facility will be housed within a twelve-story cylindrical water tank, located 700 meters underground. The $300 million venture, which has been years in the making, is on the verge of collecting data on neutrinos—tiny particles produced in atomic reactions. Researchers hope that studying these particles will shed light on one of particle physics' greatest mysteries: the hierarchy of neutrino masses. Since neutrinos can change form and exist billions of times per second in all matter, including the human body, insights into their masses could provide valuable information about processes in the early universe. Together with international scientists, including researchers from France, Germany, Italy, Russia, and the USA, Chinese physicists will analyze the radiation from neutrinos from nearby nuclear power plants in Guangdong for six years. In addition to observing terrestrial neutrinos, the JUNO project also aims to study solar neutrinos in real-time to gain deeper insights into solar processes. In the second half of 2025, JUNO will be operational and will lead the international race against larger facilities like the Deep Underground Neutrino Experiment (DUNE) in the USA—a project facing delays and budget overruns due to tensions between China and the USA. Given the political turbulence, American authorities, who previously collaborated with JUNO, have decided to focus their efforts on developing DUNE. Nevertheless, an American research team, supported by the National Science Foundation, remains involved in the project. Wang Yifang, lead scientist of JUNO, hopes that collaborative scientific engagement will send positive signals amidst geopolitical tensions. The integrity of the data obtained in the atomic domain is of utmost priority. JUNO's 600-ton spherical detector will electronically transmit the passage of neutrinos from the local power plants to partner institutions in Russia, France, and Italy. By employing multiple independent analyst teams, the accuracy of the results is to be ensured.