Speaker
Description
JUNO (Jiangmen Underground Neutrino Observatory) is a neutrino experiment located in China, 52.5 km away from two nuclear power plants. It is be the largest liquid scintillator experiment in the world, designed to detect neutrinos and antineutrinos using 20 kton of organic liquid scintillator contained in a large acrylic vessel with a diameter of 35 m.
The experiment started data taking in August 2025, and after only 59 days of data collected between August 26 and November 2, JUNO measured the solar oscillation parameters ∆m^2_{21} and sin^2 θ_{12} with a precision improved by a factor of 1.5–1.8 compared to previous experiments.
This remarkable achievement was made possible thanks to JUNO’s very large target mass, low background levels, and unprecedented energy resolution. In particular, radioactive contaminants, mainly originating from the decay chains of 238U and 232Th, can produce background events that mimic reactor antineutrino signals. For this reason, independent measurements of these backgrounds are mandatory. Furthermore, constraining these backgrounds is essential for future measurements of solar neutrinos in JUNO.
In this poster, the analysis strategies used to identify different radioactive isotopes are presented, including Bi–Po coincidence selections for 238U and 232Th, and single-spectrum analyses for 210Po. The time evolution and spatial distributions of these backgrounds are also shown, together with the most up-to-date results on the concentrations of these radioactive contaminants.