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  

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  

The Serappis (SEarch for RAre PP-neutrinos In Scintillator) project aims at a precision measurement of the flux of solar pp neutrinos on the few-percent level. Such a measurement will be a relevant contribution to the study of solar neutrino oscillation parameters and a sensitive test of the equilibrium between solar energy output in neutrinos and electromagnetic radiation (solar luminosity constraint). The concept of Serappis relies on a small organic liquid scintillator detector ( $$\sim $$  <math> <mo>∼</mo> </math>  20 m $$^3$$  <math> <msup> <mrow></mrow> <mn>3</mn> </msup> </math>  ) with excellent energy resolution ( $$\sim $$  <math> <mo>∼</mo> </math>  2.5% at 1 MeV), low internal background and sufficient shielding from surrounding radioactivity. This can be achieved by a minor upgrade of the OSIRIS facility at the site of the JUNO neutrino experiment in southern China. To go substantially beyond current accuracy levels for the pp flux, an organic scintillator with ultra-low  $$ {^{14}\hbox {C}}$$  <math> <mrow> <msup> <mrow></mrow> <mn>14</mn> </msup> <mtext>C</mtext> </mrow> </math>   levels (below  $$10^{-18}$$  <math> <msup> <mn>10</mn> <mrow> <mo>-</mo> <mn>18</mn> </mrow> </msup> </math>  ) is required. The existing OSIRIS detector and JUNO infrastructure will be instrumental in identifying suitable scintillator materials, offering a unique chance for a low-budget high-precision measurement of a fundamental property of our Sun that will be otherwise hard to access.

Lukas Bieger

Feng Gao

Christoph Genster

Alexandre Göttel

Christian Grewing

Maxim Gromov

Paul Hackspacher

Caren Hagner

Tobias Heinz

Philipp Kampmann

Michael Karagounis

Andre Kruth

Pasi Kuusiniemi

Tobias Lachenmaier

Daniel Liebau

Runxuan Liu

Kai Loo

Livia Ludhova

David Meyhöfer

Axel Müller

Pavithra Muralidharan

Lothar Oberauer

Rainer Othegraven

Nina Parkalian

Yatian Pei

Oliver Pilarczyk

Henning Rebber

Markus Robens

Christian Roth

Julia Sawatzki

Konstantin Schweizer

Giulio Settanta

Maciej Slupecki

Oleg Smirnov

Achim Stahl

Hans Steiger

Jochen Steinmann

Tobias Sterr

Matthias Stock

Jian Tang

Eric Theisen

Alexander Tietzsch

Wladyslaw Trzaska

Johannes Boom

Stefan Waasen

Cornelius Vollbrecht

Christopher Wiebusch

Bjoern Wonsak

Michael Wurm

Christian Wysotzki

Yu Xu

Ugur Yegin

Andre Zambanini

Jan Züfle

Potential for a precision measurement of solar pp neutrinos in the Serappis experiment

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

Radioactivity control strategy for the JUNO detector