The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this study, the potential of searching for proton decay in the   $ p\to \bar{\nu} K^+ $   mode with JUNO is investigated. The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via   $ p\to \bar{\nu} K^+ $   is 36.9% ± 4.9% with a background level of   $ p\to \bar{\nu} K^+ $     $ p\to \bar{\nu} K^+ $   events after 10 years of data collection. The estimated sensitivity based on 200 kton-years of exposure is   $ p\to \bar{\nu} K^+ $   years, which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies.

Chile

Angel Abusleme

France

Thomas Adam

Pakistan

Shakeel Ahmad

Rizwan Ahmed

Italy

Sebastiano Aiello

Muhammad Akram

China

Fengpeng An

Qi An

Giuseppe Andronico

JINR

Nikolay Anfimov

Vito Antonelli

Tatiana Antoshkina

Thailand

Burin Asavapibhop

João Pedro Athayde Marcondes de André

Didier Auguste

Nikita Balashov

Wander Baldini

Andrea Barresi

Davide Basilico

Eric Baussan

Marco Bellato

Antonio Bergnoli

Germany

Thilo Birkenfeld

Sylvie Blin

David Blum

Simon Blyth

Anastasia Bolshakova

Mathieu Bongrand

Clément Bordereau

Dominique Breton

Augusto Brigatti

Riccardo Brugnera

Riccardo Bruno

Antonio Budano

Mario Buscemi

Jose Busto

Ilya Butorov

Anatael Cabrera

Barbara Caccianiga

Hao Cai

Xiao Cai

Yanke Cai

Zhiyan Cai

Riccardo Callegari

Antonio Cammi

Agustin Campeny

Chuanya Cao

Guofu Cao

Jun Cao

Rossella Caruso

Cédric Cerna

Jinfan Chang

Taiwan

Yun Chang

Pingping Chen

Po-An Chen

Shaomin Chen

Xurong Chen

Yi-Wen Chen

Yixue Chen

Yu Chen

Zhang Chen

Jie Cheng

Yaping Cheng

Alexey Chetverikov

Davide Chiesa

Brazil

Pietro Chimenti

Artem Chukanov

Gérard Claverie

Catia Clementi

Belgium

Barbara Clerbaux

Selma Conforti Di Lorenzo

Daniele Corti

Flavio Dal Corso

United States

Olivia Dalager

Christophe De La Taille

Zhi Deng

Ziyan Deng

Wilfried Depnering

Marco Diaz

Xuefeng Ding

Yayun Ding

Bayu Dirgantara

Sergey Dmitrievsky

Czechia

Tadeas Dohnal

Dmitry Dolzhikov

Russia

Georgy Donchenko

Jianmeng Dong

Evgeny Doroshkevich

Marcos Dracos

Frédéric Druillole

Ran Du

Shuxian Du

Stefano Dusini

Martin Dvorak

Finland

Timo Enqvist

Heike Enzmann

Andrea Fabbri

Ulrike Fahrendholz

Donghua Fan

Lei Fan

JUNO sensitivity on proton decay →   Searches  

The vector-like top quark T is an important new fermion beyond the Standard Model. In the framework of a simplified model, we study the possibility of detecting the T through the single production of T decaying into tZ with Z decaying to neutrinos at the 14 TeV Large Hadron Collider (LHC). This simplified model includes three free parameters, that is the coupling constant <math><msup><mrow><mi>g</mi></mrow><mrow><mo>⁎</mo></mrow></msup></math>, the T quark mass <math><msub><mrow><mi>m</mi></mrow><mrow><mi>T</mi></mrow></msub></math> and the mixing parameter <math><msub><mrow><mi>R</mi></mrow><mrow><mi>L</mi></mrow></msub></math>. In order to investigate the observability of the single T production, we make a detailed detector simulation and scan the parameter space. Corresponding to an integrated luminosity of 3000 fb$^{−1}$, the correlated regions <math><msup><mrow><mi>g</mi></mrow><mrow><mo>⁎</mo></mrow></msup><mo>∈</mo><mo>[</mo><mn>0.14</mn><mo>,</mo><mn>0.5</mn><mo>]</mo><mo>(</mo><mo>[</mo><mn>0.2</mn><mo>,</mo><mn>0.5</mn><mo>]</mo><mo>)</mo></math> with <math><msub><mrow><mi>m</mi></mrow><mrow><mi>T</mi></mrow></msub><mo>∈</mo><mo>[</mo><mn>1200</mn><mspace width="0.25em"></mspace><mtext>GeV</mtext><mo>,</mo><mn>1900</mn><mspace width="0.25em"></mspace><mtext>GeV</mtext><mo>]</mo><mo>(</mo><mo>[</mo><mn>1200</mn><mspace width="0.25em"></mspace><mtext>GeV</mtext><mo>,</mo><mn>1660</mn><mspace width="0.25em"></mspace><mtext>GeV</mtext><mo>]</mo><mo>)</mo></math> can be excluded (discovered) for <math><msub><mrow><mi>R</mi></mrow><mrow><mi>L</mi></mrow></msub><mo>=</mo><mn>0</mn></math> and the correlated regions <math><msup><mrow><mi>g</mi></mrow><mrow><mo>⁎</mo></mrow></msup><mo>∈</mo><mo>[</mo><mn>0.1</mn><mo>,</mo><mn>0.5</mn><mo>]</mo></math> with <math><msub><mrow><mi>m</mi></mrow><mrow><mi>T</mi></mrow></msub><mo>∈</mo><mo>[</mo><mn>1600</mn><mspace width="0.25em"></mspace><mtext>GeV</mtext><mo>,</mo><mn>2520</mn><mspace width="0.25em"></mspace><mtext>GeV</mtext><mo>]</mo><mo>(</mo><mo>[</mo><mn>1320</mn><mspace width="0.25em"></mspace><mtext>GeV</mtext><mo>,</mo><mn>2220</mn><mspace width="0.25em"></mspace><mtext>GeV</mtext><mo>]</mo><mo>)</mo></math> can be excluded (discovered) for <math><msub><mrow><mi>R</mi></mrow><mrow><mi>L</mi></mrow></msub><mo>=</mo><mn>0.5</mn></math>.

Haitao Li

Jinjin Chao

Guoqing Zhang

Search for the singlet vector-like top quark in → Channel With at the 14 TeV LHC

Main goal of the JUNO experiment is to determine the neutrino mass ordering using a 20 kt 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 5000 of dynode PMTs from Hamamatsu Photonics K. K.(HPK).

Abid Aleem

Tsagkarakis Alexandros

João André

Weidong Bai

Chi Chan

Guoming Chen

Zhiyuan Chen

Zikang Chen

Yu Cheng

Marta Colomer Molla

Flavio Corso

Christophe Taille

Mass testing and characterization of 20-inch PMTs for JUNO

JUNO is a multi-purpose neutrino observatory under construction in the south of China. This publication presents new sensitivity estimates for the measurement of the   $ \Delta m^2_{31} $  ,   $ \Delta m^2_{31} $  ,   $ \Delta m^2_{31} $  , and   $ \Delta m^2_{31} $   oscillation parameters using reactor antineutrinos, which is one of the primary physics goals of the experiment. The sensitivities are obtained using the best knowledge available to date on the location and overburden of the experimental site, the nuclear reactors in the surrounding area and beyond, the detector response uncertainties, and the reactor antineutrino spectral shape constraints expected from the TAO satellite detector. It is found that the   $ \Delta m^2_{31} $   and   $ \Delta m^2_{31} $   oscillation parameters will be determined to 0.5% precision or better in six years of data collection. In the same period, the   $ \Delta m^2_{31} $   parameter will be determined to about   $ \Delta m^2_{31} $  % precision for each mass ordering hypothesis. The new precision represents approximately an order of magnitude improvement over existing constraints for these three parameters.

Yu Chin Cheng

Sub-percent precision measurement of neutrino oscillation parameters with JUNO  

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, ν 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 τ 3/m 3 in the ν 3 decay model, the width of the neutrino wave packet σ  x , and the intrinsic relative dispersion of neutrino momentum σ rel.

Jun Wang

Jiajun Liao

Wei Wang

João Athayde Marcondes de André

Slovakia

Andrej Babic

Jiawei Deng

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

JUNO is a massive liquid scintillator detector with a primary scientific goal of determining the neutrino mass ordering by studying the oscillated anti-neutrino flux coming from two nuclear power plants at 53 km distance. The expected signal anti-neutrino interaction rate is only 60 counts per day (cpd), therefore a careful control of the background sources due to radioactivity is critical. In particular, natural radioactivity present in all materials and in the environment represents a serious issue that could impair the sensitivity of the experiment if appropriate countermeasures were not foreseen. In this paper we discuss the background reduction strategies undertaken by the JUNO collaboration to reduce at minimum the impact of natural radioactivity. We describe our efforts for an optimized experimental design, a careful material screening and accurate detector production handling, and a constant control of the expected results through a meticulous Monte Carlo simulation program. We show that all these actions should allow us to keep the background count rate safely below the target value of 10 Hz (i.e. ∼1 cpd accidental background) in the default fiducial volume, above an energy threshold of 0.7 MeV.

Oliviero Cremonesi

Lukas Fajt

Jian Fang

Radioactivity control strategy for the JUNO detector

The OSIRIS detector is a subsystem of the liquid scintillator filling chain of the JUNO reactor neutrino experiment. Its purpose is to validate the radiopurity of the scintillator to assure that all components of the JUNO scintillator system work to specifications and only neutrino-grade scintillator is filled into the JUNO Central Detector. The aspired sensitivity level of  $$10^{-16}\hbox { g/g}$$  <math> <mrow> <msup> <mn>10</mn> <mrow> <mo>-</mo> <mn>16</mn> </mrow> </msup> <mspace width="0.333333em"></mspace> <mtext>g/g</mtext> </mrow> </math>   of  $$^{238}\hbox {U}$$  <math> <mrow> <msup> <mrow></mrow> <mn>238</mn> </msup> <mtext>U</mtext> </mrow> </math>   and  $$^{232}\hbox {Th}$$  <math> <mrow> <msup> <mrow></mrow> <mn>232</mn> </msup> <mtext>Th</mtext> </mrow> </math>   requires a large ( $$\sim 20\,\hbox {m}^3$$  <math> <mrow> <mo>∼</mo> <mn>20</mn> <mspace width="0.166667em"></mspace> <msup> <mtext>m</mtext> <mn>3</mn> </msup> </mrow> </math>  ) detection volume and ultralow background levels. The present paper reports on the design and major components of the OSIRIS detector, the detector simulation as well as the measuring strategies foreseen and the sensitivity levels to U/Th that can be reached in this setup.

Guangpeng An

Selma Lorenzo

Salvatore Costa

The design and sensitivity of JUNO’s scintillator radiopurity pre-detector OSIRIS

Atmospheric neutrinos are one of the most relevant natural neutrino sources that can be exploited to infer properties about cosmic rays and neutrino oscillations. The Jiangmen Underground Neutrino Observatory (JUNO) experiment, a 20 kton liquid scintillator detector with excellent energy resolution is currently under construction in China. JUNO will be able to detect several atmospheric neutrinos per day given the large volume. A study on the JUNO detection and reconstruction capabilities of atmospheric  $$\nu _e$$  <math> <msub> <mi>ν</mi> <mi>e</mi> </msub> </math>   and  $$\nu _\mu $$  <math> <msub> <mi>ν</mi> <mi>μ</mi> </msub> </math>   fluxes is presented in this paper. In this study, a sample of atmospheric neutrino Monte Carlo events has been generated, starting from theoretical models, and then processed by the detector simulation. The excellent timing resolution of the 3” PMT light detection system of JUNO detector and the much higher light yield for scintillation over Cherenkov allow to measure the time structure of the scintillation light with very high precision. Since  $$\nu _e$$  <math> <msub> <mi>ν</mi> <mi>e</mi> </msub> </math>   and  $$\nu _\mu $$  <math> <msub> <mi>ν</mi> <mi>μ</mi> </msub> </math>   interactions produce a slightly different light pattern, the different time evolution of light allows to discriminate the flavor of primary neutrinos. A probabilistic unfolding method has been used, in order to infer the primary neutrino energy spectrum from the detector experimental observables. The simulated spectrum has been reconstructed between 100 MeV and 10 GeV, showing a great potential of the detector in the atmospheric low energy region.

Enrico Bernieri

JUNO sensitivity to low energy atmospheric neutrino spectra

We present the calibration strategy for the 20 kton liquid scintillator central detector of the Jiangmen Underground Neutrino Observatory (JUNO). By utilizing a comprehensive multiple-source and multiple-positional calibration program, in combination with a novel dual calorimetry technique exploiting two independent photosensors and readout systems, we demonstrate that the JUNO central detector can achieve a better than 1% energy linearity and a 3% effective energy resolution, required by the neutrino mass ordering determination.

Shenjian Chen

Anna Chuvashova

Damien Dornic

Calibration strategy of the JUNO experiment

The Jiangmen Underground Neutrino Observatory (JUNO) features a 20 kt multi-purpose underground liquid scintillator sphere as its main detector. Some of JUNO's features make it an excellent location for   $ ^8 $  B solar neutrino measurements, such as its low-energy threshold, high energy resolution compared with water Cherenkov detectors, and much larger target mass compared with previous liquid scintillator detectors. In this paper, we present a comprehensive assessment of JUNO's potential for detecting   $ ^8 $  B solar neutrinos via the neutrino-electron elastic scattering process. A reduced 2 MeV threshold for the recoil electron energy is found to be achievable, assuming that the intrinsic radioactive background   $ ^8 $  U and   $ ^8 $  Th in the liquid scintillator can be controlled to 10   $ ^8 $   g/g. With ten years of data acquisition, approximately 60,000 signal and 30,000 background events are expected. This large sample will enable an examination of the distortion of the recoil electron spectrum that is dominated by the neutrino flavor transformation in the dense solar matter, which will shed new light on the inconsistency between the measured electron spectra and the predictions of the standard three-flavor neutrino oscillation framework. If   $ ^8 $   eV   $ ^8 $  , JUNO can provide evidence of neutrino oscillation in the Earth at approximately the 3   $ ^8 $   (2   $ ^8 $  ) level by measuring the non-zero signal rate variation with respect to the solar zenith angle. Moreover, JUNO can simultaneously measure   $ ^8 $   using   $ ^8 $  B solar neutrinos to a precision of 20% or better, depending on the central value, and to sub-percent precision using reactor antineutrinos. A comparison of these two measurements from the same detector will help understand the current mild inconsistency between the value of   $ ^8 $   reported by solar neutrino experiments and the KamLAND experiment.