Status of the JUNO Experiment

Gaosong Li Institute of High Energy Physics, CAS On behalf of the JUNO collaboration

IAS Program on High Energy Physics Jan 20, 2021 1 JUNO Experiment

Guang Zhou

2.5 h drive Lufeng Shen Zhen Huizhou NPP NPP Zhu Hai Daya Bay NPP Hong Kong Macau 53 km 53 km Taishan NPP Yangjiang NPP

2 Timeline

2022 • Detector ready for data taking 2019-2021 • Electronics production starts 2018 • Civil construction and • PMT potting lab preparation • Start delivery of completed 2017 surface building • Detector construction • PMT testing • Start production of start acrylic sphere 2016 • TT arrived • PMT production start Collaboration 2014 • CD parts production 2015 start • PMT production• Yellow book line setup published • CD parts R&D • Civil 2014 construction • International start collaboration established • Conceptual design 3 A Multipurpose Neutrino Observatory

26.6 GWth, 53 km

~60 / day

4 From J. Pedro Ochoa-Ricoux Mass Ordering

DYB near DYB far JUNO

• Determine mass ordering by resolving the tiny phase difference in the oscillated spectrum • 3휎 sensitivity to neutrino mass ordering with 6 years’ data • 4휎 with constraints from accelerator experiments

5 Precision Measurement of Oscillation Parameters

• Sub-percent precision on 2 2 2 sin 휃12 , Δ푚21, Δ푚31 • Essential to test the neutrino oscillation framework precisely • An update of precision measurement is under preparation

6 Rich Physics Potential

• Supernova neutrinos (SN) • 10k events (5000 IBD) for SN @ 10kpc • Sensitivity to flavor content, energy spectrum and time evolution • Diffusive supernova neutrino background (DSNB) • ~3휎 sensitivity with 10 years’ data • Atmospheric neutrinos • Mass ordering effect from MSW effect • Solar Neutrino • 60k ES signal and 30k background in 10 years’ data taking • Solar oscillation parameters using solar 휈푒 and reactor anti-휈푒 • Geo-neutrinos • Explore origin and thermal evolution of the earth with 400-500 events per year • Multi-messenger • Lower detector threshold to O(10) keV • Real time monitoring of the MeV transient neutrino sky • Proton decay • Competitive sensitivity through 푝 → 휈ҧ + 퐾+

7 Country Institute Country Institute Country Institute Armeni Yerevan Physics China IMP-CAS Germany FZJ-IKP a Institute Universite libre de Belgium China SYSU Germany U. Mainz JUNO Collaboration Bruxelles Brazil PUC China Tsinghua U. Germany U. Tuebingen Brazil UEL China UCAS Italy INFN Catania Chile PCUC China USTC Italy INFN di Frascati Chile UTFSM China U. of South China Italy INFN-Ferrara China BISEE China Wu Yi U. Italy INFN-Milano INFN-Milano China Beijing Normal U. China Wuhan U. Italy Bicocca China CAGS China Xi'an JT U. Italy INFN-Padova China ChongQing University China Xiamen University Italy INFN-Perugia China CIAE China Zhengzhou U. Italy INFN-Roma 3 China DGUT China NUDT Latvia IECS China ECUST China CUG-Beijing Pakistan PINSTECH (PAEC) China Guangxi U. China ECUT-Nanchang City Russia INR Moscow Harbin Institute of China Croatia PDZ/RBI Russia JINR Technology China IHEP Czech Charles U. Russia MSU China Jilin U. Finland University of Jyvaskyla Slovakia FMPICU Taiwan- National Chiao-Tung China Jinan U. France LAL Orsay China U. Taiwan- China Nanjing U. France CENBG Bordeaux National Taiwan U. China Taiwan- China Nankai U. France CPPM Marseille National United U. China China NCEPU France IPHC Strasbourg Thailand NARIT China Pekin U. France Subatech Nantes Thailand PPRLCU German China Shandong U. FZJ-ZEA Thailand SUT y German China Shanghai JT U. RWTH Aachen U. USA UMD y German China IGG-Beijing TUM USA UC Irvine y 669 members from 77 institutes German China IGG-Wuhan U. Hamburg 8 y Detector Technology

• A 20-kton liquid scintillator calorimeter • Key requirements • Excellent energy resolution: < 3%/√퐸 within [1, 8] MeV • Energy scale uncertainty < 1% • Low radioactive background • Pulse shape discrimination capability for PID • Based on LS photon emission time difference for different particle types • e-/e+ vs 훼/p/n-recoil

9 Central Detector

• 35 m diameter acrylic sphere • Stainless steel truss • 20,000 tons purified liquid scintillator • 18,000 20-inch PMTs • 25,600 3-inch PMTs • Filling/Overflow/Circulation (FOC) system

1010 Liquid Scintillator

• Four different plants for LS purification to achieve high • Low radioactive backgrounds attenuation length and low radioactive background • 10-15 g/g U/Th for reactor antineutrinos • Finished a pilot LS purification test at Daya Bay • 10-17 g/g U/Th for solar neutrinos • LS recipe: LAB + 2.5 g/L PPO + (1-4) mg/L bis-MSB (arXiv: • An online radioactivity investigation system 2007.00314) (OSIRIS) will be built • Attenuation Length: > 20 m @430 nm

11 20-inch PMTs

• 18,000 20-inch PMTs • 13,000 MCP-PMT developed for JUNO by NNVT, use of transmission and reflection cathodes to increase quantum efficiency • 5,000 Dynode PMTs (Hamamatsu, R12860HQE), 2.7 ns FWHM TTS • Average photon detection efficiency 28.4%

• HV divider mass production is ongoing • 7000 PMTs have been potted with multiple water- proof layers • Implosion protection covers were designed and produced

12 3-inch PMTs

• 25,600 3-inch HZC Photonics PMTs • Double calorimetry system in JUNO together with the 20-inch PMT system • Correct non-linear response of 20-inch PMT • Increase dynamic range • Standalone measurement of solar neutrino oscillation parameters

• All 3-inch PMTs have been produced

13 Calibration System

• 1D: Automatic Calibration Unit (ACU) • 2D: Cable Loop System (CLS) and Guide Tube Calibration System (GTCS) • 3D: Remotely Operated Vehicle (ROV) • Auxiliary systems: Calibration house, Ultrasonic Sensor System (USS), CCD and A Unit for Researching Online the LSc tRAnsparency (AURORA)

14 Muon Veto System

• Water Cerencov detector • ~2400 20-inch MCP-PMT used • 35 ktons ultrapure water with circulation • Shield CD from ambient radioactivity and neutrons induced by cosmic rays • Veto muon induced backgrounds • Detection efficiency is expected to be larger than 99% • Top tracker • Reuse the Target Tracker walls from the OPERA experiment • 3-layer plastic scintillator modules are already at JUNO site

15 Taishan Antineutrino Observatory CDR: arXiv 2005.08745 • TAO, a satellite experiment of JUNO • Precision measurement of the reactor anti-neutrino spectrum with sub-percent energy resolution in the major energy range (~2% @ 1 MeV) • Provide model-independent reference spectrum for JUNO • Provide a benchmark measurement to examine nuclear database • Conceptual design released • 10 m2 SiPM with QE=50% • 2.8 ton GdLS (FV mass 1 ton) at -50 oC • 4500 p.e./MeV from MC simulation

• 30 m from Taishan reactor (4.6 GWth) • 2000 antineutrinos/day with 50% efficiency • Expected to start operation in 2022

16 Civil Construction

• Slope tunnels and vertical shafts are finished. • Experimental cavern digging was just finished in Dec 2020.

17 Conclusion

• JUNO is a multipurpose neutrino observatory with rich physics potential, including determining neutrino mass ordering, precisely measuring the oscillation parameters, observing supernova neutrinos, detecting atmospheric neutrinos, solar neutrinos, geo-neutrinos etc. • The sub-system R&D and production are well underway • JUNO is expected to start data taking in 2022 • Stay tuned!

18 Backup

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