Status of JUNO

Liang Zhan

Institute of High Energy Physics, Beijing

On behalf of the JUNO Collaboration

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• Large θ13 opens a door to neutrino MO and CP violating phase, as the focus of next generation neutrino experiments.

• MO can be determined utilizing

– Matter effects of accelerator (DUNE, T2HK) and atmospheric (PINGU, HK, ORCA, INO) neutrinos

– Oscillation interference effects of reactor neutrinos driven by Δm232

and Δm231

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Neutrino Mass Ordering

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Precise measurement of reactor antineutrino spectrum with oscillation

Daya Bay

JUNO

• Independent of the θ23, CP phase and (almost) matter effect

• Complementary to atmospheric &accelerator neutrino experiments

NMO Determination by Reactor Antineutrino

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Yangjiang NPP

TaishanNPP

Daya Bay

NPP

Huizhou

NPP

Lufeng

NPP

53 km

53 km

Hong Kong

Macau

Guang Zhou

Shen Zhen

Zhu Hai

2.5 h drive

Kaiping,Jiangmen city,Guangdong Province

Previous site candidate

Overburden ~ 700 m by 2020: 26.6 GW

• Jiangmen Underground Neutrino Observatory• 27-36 GW reactor power, 20 kton LS detector, 3%/√E (MeV) energy resolution• Proposed in 2008, approved in 2013, civil construction started in 2015

JUNO Experiment

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Exposure

Δχ2 contours• 20 kton detector 100000 antineutrino events in 6 years

• 3%/√E (MeV) energy resolution precise spectral measurements

KamLAND Borexino Daya Bay JUNO

Target mass 1 kton ~ 300 tons 20 x 8 tons 20 kton

Photo-coverage 34% 30% 12% 77%

P.E. per MeV ~250 ~500 ~160 1200

E resolution@ 1 MeV 6% 5% 8% 3%

nominal

Requirements on JUNO experiment

Size Δχ2MO

Ideal 52.5 km +16

Core distr. Real -3

DYB & HZ Real -1.7

Spectral Shape 1% -1

B/S (rate) 6.3% -0.6

B/S (shape) 0.4% -0.1

JUNO MH sensitivity with 6 years' data assuming full reactor power

J. Phys. G43:030401 (2016)

Sensitivity of NMO Determination

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0.24%0.59% 0.54%0.67%0.27%0.44%E resolution

Nominal+BG, +1% b2b+1% EScale , +1% EnonL

sin2 θ12 0.54% 0.67%

Δm221 0.24% 0.59%

Δm232 0.27% 0.44%

Probing the unitarity of UPMNS to ~1%, more precise than CKM matrix elements!

Current precision

J. Phys. G43:030401 (2016)∆𝑚𝑠𝑜𝑙

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∆𝑚𝑎𝑡𝑚2

Precision Measurement

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Cosmic-ray

~ 250k /day

Atmospheric several/day

Geo 1.1 /day

Solar (10s-1000s) /day

Reactor , 60 /day

700 m

Supernova 5-7k in 10 s for 10 kpc

20k ton LS

36 GWth, 53 km

0.0037 Hz/m2

215 GeV10% muon bundles

Proton decay

Beyond the Reactor Antineutrinos

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Supernova Burst Neutrinos

• Real-time detection of SN burst neutrinos in ~10 s

• IBD is the golden channel, ~5000 events for SN@10 kpc

• Full flavor detection and low threshold energy ~0.2 MeV in liquid scintillator with special trigger design (Later talk on “Multi-messenger trigger system of JUNO”, by Ziping Ye)

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Burst Accretion Cooling

JUNO Detector

• 20-kton liquid scintillator in 35.4 m acrylic sphere• 18000 20’’ and 25000 3’’ PMTs to detect photons with a

coverage of 77%.

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• Top tracker: plastic scintillator

• Water pool: Cherekovveto detector (φ40 x 40 m)

• Design goals: large target mass with an unprecedented energy resolution 3%/√E (MeV)

Central Detector

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• Stainless steel structrue: ID 40.1 m, OD 41.1 m • 30 longitudes and 23 layers

• Acrylic sphere: ID 35.4m, thickness: 12 cm• 265 pieces of 3 m×8 m panels

• Transparency > 96% in pure water• 1ppt level of U/Th/K in acrylic sample• Production company: Donchamp acrylic

Acrylic panel Onsite assembly Bonding machine Node test

• System design & goal:– Long attenuation length: 15 m

>20 m• Improve raw materials • Improve the production process• Purification systems

– Al2O3 Filtration column– Distillation– Water extraction– Nitrogen stripping

– Optimizing light yield for JUNO：• 2.5 g/L PPO + 3 mg/L Bis-MSB

– Low radioactive backgrounds:• 10-15 g/g for IBD• 10-17 g/g for solar neutrinos

• OSIRIS– An online detector with 20 t LS for

a sensitivity of 10-15 g/g per day

A pilot LS purification system at Daya Bay for R&D

Liquid Scintillator

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Double calorimetry

• 20” PMTs (75% photon-coverage)– 15,000 MCP-PMTs from NNVT

– 5,000 dynode PMTs from Hamamatsu

• 3” PMTs (2% photon-coverage)– 25,000 PMTs from HZC

– Photon counting

– Extend dynamic range of muon measurements

Characteristics unitMCP-PMT

（NNVC）R12860

（Hamamatsu）

Detection Efficiency (QE*CE*area)

% 28.3% 28.1%

P/V of SPE 3.5, > 2.8 3, > 2.5

TTS on the top point ns ~12, < 15 2.7, < 3.5

Rise time/ Fall time ns 2/12 5/9

Anode Dark Count Hz 20K, < 30K 10K, < 50K

After Pulse Rate % 1, <2 10, < 15

Radioactivity of glass ppb238U:50

232Th:5040K: 20

238U:400

232Th:40040K: 40

20” MCP-PMT 20” Dynode-PMT 3.1” PMT

MCP-PMT: A new type of PMT developed by IHEP & NNVC based on MCP to collect photoelectrons

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Calibration• Methods with five systems

– Routinely Source into LS by • ACU: at central axis• Rope Loop: a plane

– Source into Guided Tube– Submarine: anywhere in the LS– Laser Fiber: optical photons

• Choice of sources & location scan– Simulation shows that the

response map of the detector can be obtained

• R&D on key technical issues– Source deployment– Source locating system

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Muon Veto

Top Tracker

Water Cherenkov detector

9LiRock

• Goal of muon veto • Active and passive shielding• Muon tracking and cosmogenic isotope

study• Earth magnetic field (EMF) coil shielding for

20” PMTs

• Water Cerenkov detector • ~2000 20” PMTs inside EMF • 35 ktons ultrapure water with circulation• Muon detection efficiency > 95%• Radon control < 0.2 Bq/m3

• Fast neutron background ~0.1 /day

• Top tracker• Reuse OPERA’s target tracker • Cover half of the top area

EMF coil shielding15

• Taishan Antineutrino Observatory (TAO), a ton-level, high energy resolution LS detector at 30-35 m from the core, a satellite exp. of JUNO.

• Measure reactor neutrino spectrum with <2 %/√E (MeV) resolution.

– model-independent reference spectrum for JUNO

– a benchmark for investigation of the nuclear database

• Ton-level Liquid Scintillator (Gd-LS)

• Full coverage of SiPM w/ PDE > 50%

• Operate at -50 ℃ (SiPM dark noise)

• 4500 p.e./MeV

• Taishan Nuclear Power Plant, 30-35 m from a 4.6 GWth core

• 2000 IBD/day in fiducial volume

• Online in 2021

JUNO-TAO

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The JUNO Collaboration

77 Institutions, ~600 collaborators• China (34), Taiwan, China (3), Thailand (3),

Pakistan, Armenia• Italy (8), Germany (7), France (5), Russia

(3), Belgium, Czech, Finland, Slovakia, Latvia

• Brazil (2), Chile (2), USA (3)

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Civil Construction

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Vertical shaft and slope tunnel completed

Collaboration 2014

2014International collaboration established

2015• PMT production

line setup• CD parts R&D• Civil

construction start

2016• PMT

production start

• CD parts production start

• Yellow book published

2017• PMT testing

start• TT arrived

2018• PMT potting• Start delivery

of surface building

• Start production of acrylic sphere

2019-2020• Electronics

production starts• Civil construction

and lab preparation completed

• Detector construction

2021• Complete the

construction and start data taking

JUNO surface building

Slope tunnel: 1340m

Vertical Shaft: 581m

JUNO Schedule

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Summary

• JUNO has rich physics programe with the main goals to determine neutrino mass ordering and precisely measure the oscillation parameters.

• With 6 years data taking, the sensitivity of mass hierarchy can reach 3 σ (Δχ2 = 9).

• JUNO experiment is under construction and is expected to start data taking in 2021.

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Thanks!

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