Status of the Veto System of JUNO

International audienceThe JUNO experiment is under construction in China. Its main goal is to determine the neutrino mass ordering via the precise measurement of the energy spectrum of anti-neutrinos from nuclear reactors 53 km away. For JUNO's measurements, it is essential to suppress and control the background rate that mimic the signal from anti-neutrinos in the Central Detector (CD). The backgrounds that are hardest to identify are the cosmogenic isotopes produced by atmospheric muons crossing the detector. To suppress this background, a veto will be applied along the muon track. The Veto System will be employed to provide precise information about passing muons. The Veto System of JUNO consists of the Water Cherenkov Detector (WCD), an instrumented ultra-pure water buffer surrounding the CD, and the Top Tracker, a 3-layers plastic scintillator detector covering 1/3 of the area above the WCD. This poster presented JUNO's Veto System design and status

Current status of JUNO Top Tracker

International audienceThe JUNO experiment is a multi-purpose antineutrino oscillation experiment with the main objective of determining the neutrino mass hierarchy with a sensitivity better than 3$\sigma$, which requires JUNO to have an energy resolution better than 3% at 1MeV. The JUNO Central Detector, a 20 kton liquid scintillator detector, will be built with high PMT photocathode coverage and good transparency for this purpose.Despite the 700m overburden, the atmospheric muon-induced background is still estimated to be non negligible compared to the expected signal for the neutrino mass hierarchy determination. A veto system was designed for muon detection to tag and to suppress this background. It consists of two subsystems: the Top Tracker and the Water Cherenkov Detector. The Top Tracker is a 3-layer muon tracker covering about 60% of the top surface above the JUNO water pool and will provide precise tracking for atmospheric muons. These well reconstructed muons are essential in the veto strategy for rejecting cosmogenic isotope background. Combining the muon information from the Top Tracker and the Water Cherenkov Detector, most of the atmospheric muon-induced background can be removed.This proceeding will present the current status and the expected performance of the JUNO Top Tracker

Damping signatures at JUNO, a medium-baseline reactor neutrino oscillation experiment

Abstract We study damping signatures at the Jiangmen Underground Neutrino Observatory (JUNO), a medium-baseline reactor neutrino oscillation experiment. These damping signatures are motivated by various new physics models, including quantum decoherence, nu(3) decay, neutrino absorption, and wave packet decoherence. The phenomenological effects of these models can be characterized by exponential damping factors at the probability level. We assess how well JUNO can constrain these damping parameters and how to disentangle these different damping signatures at JUNO. Compared to current experimental limits, JUNO can significantly improve the limits on tau(3)/m(3) in the nu(3) decay model, the width of the neutrino wave packet sigma(x), and the intrinsic relative dispersion of neutrino momentum sigma(rel)

Mass Testing and Characterization of 20-inch PMTs for JUNO

Main goal of the JUNO experiment is to determine the neutrino mass ordering using a 20kt liquid-scintillator detector. Its key feature is an excellent energy resolution of at least 3 % at 1 MeV, for which its instruments need to meet a certain quality and thus have to be fully characterized. More than 20,000 20-inch PMTs have been received and assessed by JUNO after a detailed testing program which began in 2017 and elapsed for about four years. Based on this mass characterization and a set of specific requirements, a good quality of all accepted PMTs could be ascertained. This paper presents the performed testing procedure with the designed testing systems as well as the statistical characteristics of all 20-inch PMTs intended to be used in the JUNO experiment, covering more than fifteen performance parameters including the photocathode uniformity. This constitutes the largest sample of 20-inch PMTs ever produced and studied in detail to date, i.e. 15,000 of the newly developed 20-inch MCP-PMTs from Northern Night Vision Technology Co. (NNVT) and 5,000 of dynode PMTs from Hamamatsu Photonics K. K.(HPK)