Initial performance results of the JUNO detector
Abstract
The Jiangmen Underground Neutrino Observatory (JUNO) started physics data taking on 26 August 2025. JUNO consists of a 20-kton liquid scintillator central detector, surrounded by a 35 kton water pool serving as a Cherenkov veto, and almost 1000 m2 of plastic scintillator veto on top. The detector is located in a shallow underground laboratory with an overburden of 1800 m.w.e. This paper presents the performance results of the detector, extensively studied during the commissioning of the water phase, the subsequent liquid scintillator filling phase, and the first physics runs. The liquid scintillator achieved an attenuation length of 20.6 m at 430 nm, while the high coverage PMT system and scintillator together yielded about 1785 photoelectrons per MeV of energy deposit at the detector centre, measured using the 2.223 MeV γ from neutron captures on hydrogen with an Am-C calibration source. The reconstructed energy resolution is 3.4% for two 0.511 MeV γ at the detector centre and 2.9% for the 0.93 MeV quenched Po-214 alpha decays from natural radioactive sources. The energy nonlinearity is calibrated to better than 1%. Intrinsic contaminations of U-238 and Th-232 in the liquid scintillator are below 10−16 g/g, assuming secular equilibrium. The water Cherenkov detector achieves a muon detection efficiency better than 99.9% for muons traversing the liquid scintillator volume. During the initial science runs, the data acquisition duty cycle exceeded 97.8%, demonstrating the excellent stability and readiness of JUNO for high-precision neutrino physics.
Related
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BibTeX
@article{abusleme2026initial,
title = {{Initial performance results of the JUNO detector}},
author = {Angel Abusleme and Thomas Adam and Kai Adamowicz and David Adey and Shakeel Ahmad and Rizwan Ahmed and Timo Ahola and Sebastiano Aiello and Fengpeng An and Guangpeng An and Costas Andreopoulos and Giuseppe Andronico and João Pedro Athay de Marcondes de André and Nikolay Anfimov and Vito Antonelli and Tatiana Antoshkina and Burin Asavapibhop and Didier Auguste and Margherita Buizza Avanzini and Andrej Babic and Jingzhi Bai and Weidong Bai and Nikita Balashov and Roberto Barbera and Andrea Barresi and Davide Basilico and Eric Baussan and Beatrice Bellantonio and Marco Bellato and Jeanluc Beney and Marco Beretta and Antonio Bergnoli and Enrico Bernieri and Nikita Bessonov and David Biaré and Daniel Bick and Lukas Bieger and Svetlana Biktemerova and Thilo Birkenfeld and David Blum and Simon Blyth and Sara Boarin and Manuel Boehles and Anastasia Bolshakova and Mathieu Bongrand and Aurélie Bonhomme and Clément Bordereau and Matteo Borghesi and Augusto Brigatti and Timothee Brugiere and Riccardo Brugnera and Riccardo Bruno and Jonas Buchholz and Antonio Budano and Max Buesken and Mario Buscemi and Severino Bussino and Jose Busto and Ilya Butorov and Marcel Büchner},
journal = {Chin.Phys.C},
year = {2026},
month = sep,
doi = {10.1088/1674-1137/ae3dc1},
eprint = {2511.14590},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05393732v1},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Initial performance results of the JUNO detector
AU - Angel Abusleme
AU - Thomas Adam
AU - Kai Adamowicz
AU - David Adey
AU - Shakeel Ahmad
AU - Rizwan Ahmed
AU - Timo Ahola
AU - Sebastiano Aiello
AU - Fengpeng An
AU - Guangpeng An
AU - Costas Andreopoulos
AU - Giuseppe Andronico
AU - João Pedro Athay de Marcondes de André
AU - Nikolay Anfimov
AU - Vito Antonelli
AU - Tatiana Antoshkina
AU - Burin Asavapibhop
AU - Didier Auguste
AU - Margherita Buizza Avanzini
AU - Andrej Babic
AU - Jingzhi Bai
AU - Weidong Bai
AU - Nikita Balashov
AU - Roberto Barbera
AU - Andrea Barresi
AU - Davide Basilico
AU - Eric Baussan
AU - Beatrice Bellantonio
AU - Marco Bellato
AU - Jeanluc Beney
AU - Marco Beretta
AU - Antonio Bergnoli
AU - Enrico Bernieri
AU - Nikita Bessonov
AU - David Biaré
AU - Daniel Bick
AU - Lukas Bieger
AU - Svetlana Biktemerova
AU - Thilo Birkenfeld
AU - David Blum
AU - Simon Blyth
AU - Sara Boarin
AU - Manuel Boehles
AU - Anastasia Bolshakova
AU - Mathieu Bongrand
AU - Aurélie Bonhomme
AU - Clément Bordereau
AU - Matteo Borghesi
AU - Augusto Brigatti
AU - Timothee Brugiere
AU - Riccardo Brugnera
AU - Riccardo Bruno
AU - Jonas Buchholz
AU - Antonio Budano
AU - Max Buesken
AU - Mario Buscemi
AU - Severino Bussino
AU - Jose Busto
AU - Ilya Butorov
AU - Marcel Büchner
PY - 2026
DA - 2026/09/22
JO - Chin.Phys.C
DO - 10.1088/1674-1137/ae3dc1
UR - https://hal.science/hal-05393732v1
AB - The Jiangmen Underground Neutrino Observatory (JUNO) started physics data taking on 26 August 2025. JUNO consists of a 20-kton liquid scintillator central detector, surrounded by a 35 kton water pool serving as a Cherenkov veto, and almost 1000 m^2 of plastic scintillator veto on top. The detector is located in a shallow underground laboratory with an overburden of 1800 m.w.e. This paper presents the performance results of the detector, extensively studied during the commissioning of the water phase, the subsequent liquid scintillator filling phase, and the first physics runs. The liquid scintillator achieved an attenuation length of 20.6 m at 430 nm, while the high coverage PMT system and scintillator together yielded about 1785 photoelectrons per MeV of energy deposit at the detector centre, measured using the 2.223 MeV γ from neutron captures on hydrogen with an Am-C calibration source. The reconstructed energy resolution is 3.4% for two 0.511 MeV γ at the detector centre and 2.9% for the 0.93 MeV quenched Po-214 alpha decays from natural radioactive sources. The energy nonlinearity is calibrated to better than 1%. Intrinsic contaminations of U-238 and Th-232 in the liquid scintillator are below 10^−16 g/g, assuming secular equilibrium. The water Cherenkov detector achieves a muon detection efficiency better than 99.9% for muons traversing the liquid scintillator volume. During the initial science runs, the data acquisition duty cycle exceeded 97.8%, demonstrating the excellent stability and readiness of JUNO for high-precision neutrino physics.
ER -