Prospects and Status of theJUNO detector
Cong Guo
Institute of High Energy Physics, CASOn Behalf of the JUNO collaboration

Outline An overview of JUNO
Physics prospects
 The project status of JUNO

• Liquid scintillator• Central detector• PMT• Veto detector• Calibration system• TAO detector
 Conclusion

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Jiangmen Underground Neutrino Observatory
Project:
 Major goal：NMO determination；
 Main Source : Reactor neutrinos; Target: 20 kton liquid scintillator ; Location: 700m underground; Approved in 2013, Construction sinceJUNO

2015, operation in 2023;

Daya BayNPP

Daya Bay

Huizhou

LufengYangjiang

TaishanStatusOperation Planned

PlannedOperation

Operation

Power17.4 GWth 17.4 GWth 17.4 GWth 17.4 GWth

9.2 GWth3

JUNO Collaboration

18 countries/regions，77 institutions，~670 members

4Physics Prospects
JUNO：A multipurpose neutrino experiment

Phyiscs:
 Determine neutrino mass ordering; Precise measurements of threeneutrino oscillation parameters;
 Supernova neutrinos; Solar neutrinos; Atmospheric neutrinos; Geo-neutrinos; Exotic searches, proton decay;
5Neutrino Mass OrderingP  (L / E )  1 - P21 - P31 - P32
P21  cos4(13 )sin 2(212 )sin 2( 21 )P31  cos2(12 )sin 2(213 )sin 2( 31 )ee

P32  sin 2(12 )sin 2(213 )sin 2( 32 )
 ij  m ij2 L / 4E (m ij2  m i2  m j2 )
 JUNO determines the NMO using the oscillation interplay
between ∆m2 31 and ∆m2 32 at a medium reactor baseline(∼53 km).; JUNO will resolve the NMO using precision spectral
measurements of reactor antineutrinos；
 3σ neutrino mass ordering sensitivity within 6 years.
 Key: Energy resolution(3%@1MeV);
6Physics Prospects• Supernova neutrinos•

Sensitive to flavor content, energyspectrum, time evolution;•10000 events (5000 via IBD) for SN @The neutrino event
spectra with respect
to the visible energy
for a typical SN @10kpc

10kpc;• Solar neutrinos•~60k signals and 30k backgrounds areexpected in 10 years；•

Shed new light on current tension in Δm221

Expected signal andbackground spectrumof 8B neutrino

between solar and reactor neutrinos

measurement with the same detector;
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Physics Prospects• Diffuse Supernova Neutrino
Background (DSNB)•

3σ sensitivity in 10 years or strongest
constraint;•2-4 IBDs per year above reactor neutrino

The DSNB signal
dominates in theenergy range of
11-22 MeV

energy range;• Atmospheric neutrinos•

Complimentary neutrino mass ordering
sensitivity via matter effect• Geo-neutrino••

Explore origin and thermal evolution of theEarth
400 - 500 neutrinos per year

• Proton decay•

Competitive sensitivity through8

JUNO Detector
Top Tracker

Calibration RoomPure water Room

LS-Filling Room

Earth Magnetic
Field shieldingcoils

PMT:• 17612 20’’ PMTs
• 25600 3’’ PMTs
• 77.5% Coverage
WCD:• 40 kton Pure water• 2400 20’’ PMTs

Acrylic Sphere : Φ 35.4m

Stainless steel lattice shell: Φ 40.1m

Pool Depth: 44m

Central detector:• Steel structure• Acrylic Sphere• 20kton LS

Water Pool: Φ 43.5m
9Status : Liquid Scintillator
 Using a recipe optimized from Daya Bay’s experience;
 Tested and changed to be more suitable for JUNO;
 Higher light yield and more transparent;• 2.5g/L PPO;
• 3mg/L Bis-MSB;• Filtration with Al2O3 column(Based on the“absorption” technique to remove the impurities

and increase the attenuation length of LAB); Low background, 10-15 U/Th for reactor neutrinos and10-17 U/Th for solar neutrinos;

Linear alkylbenzene(LAB) as solvent+3 g/L PPO+
15 mg/L
Bis-MSB• Distillation: Remove heavy metal and improvetransparency ;• Water extraction: Remove U/Th/K;

The recipe of Daya Bay LS• Gas stripping: Remove Ar/Kr/Rn;
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Status : Liquid Scintillator

 5 kton LS storage tank and LN2 tower are ready, inner pressure of LS tank is ~0.5bar;
 Alumina Filtration Plant has been delivered onsite; Other work is well in progress;
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Status : OSIRIS
 Online Scintillator Internal Radioactivity
Investigation System (OSIRIS); Monitor the radio-purity of the LS during the6-months filling of JUNO, to ensure that nocontaminated scintillator arrives inside CD.
 Sensitivity: 10-16g/g for U/Th within 24h

measurement;
 Measure ~19 t LS per day; Detector:• Φ3m*H3m Acrylic tank;• 81 20’’ PMTs for photon detection;• 2.5m water shielding + 12 20’’ PMTs;
 Water tank is onsite, acrylic vessel is underproduction, others are well in progress;

The OSIRIS facility
12Status : CD Acrylic
 Central Detector(CD): Acrylic Sphere + Stainless Steel Support ; The acrylic sphere is composed of 265 pieces of spherical panels; Thickness:120mm, Net weight: ~600 tons;

 Transparency > 96% in pure water;
 DonChamp won the bid at 2017.02• Flat panel production finished and thermal forming is in progress;

 Process control for low radiation background:• Filter in MMA material & Special reaction kettle/pipe;• Moulding: pure water/clean room;

The Acrylic Sphere• Thermoforming: film or placket to shield the dust and radon;• Bonding: filled with clean air or N2;• Shield Rn: plastic film on the surface of the acrylic;• Clean the inner surfaces of the acrylic sphere: The samples for acrylic has met the 1ppt requirement for U/Th;

Thermoforming of spherical panel
3m x 8m x 120mm13

Status : JUNO PMTs
 Two sizes of PMTs will be used toPMT
9mm Acrylic
Coverfully(~78%) cover CD;• 17612 20’’ PMTs for CD (~75%)

2mm SST
Cover+ 2400 20’’ PMTs for Veto;• 25600 3’’ PMTs(~2.7%);

Hook Implosion protection; Waterproof potting;Clamp

 Custom-made divider andelectronics;

Waterproof potting Stringent quality control• All PMTs will be tested before
and after potting;14

Status : Large PMT
 Two types of 20‘‘ PMTs will be used:• 15,000 Micro-channel plates PMTs (MCP-PMT,NNVT);• 5,000 Dynode PMTs (Hamamatsu, R12860HQE) ; MCP-PMTs are custom designed and manufactured for JUNO ; Bare PMT testing completed, mass potting is on-going;
CharacteristicUnit

MCP-PMT

Dynode PMTDetection efficiency(QE*DE)

%

28.7

28.1

P/V of SPE

ns3.5, >2.8

3, >2.5

TTS on top pointns~12, <15

2.7, <3.5

Rise/Fall time

ns

2/12

5/9

Anode dark count

Hz20K, <30K

10K, <50K

After pulse rate%

1, <210, <15

238U: 75

238U: 400

232Th: 74

232Th: 400

40K: 4

40K: 40

Radioactivity ofglassppb

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Status : Small PMT
 Improve the energy scale precision, in particular, the coupling of non-linearity and non-uniformity.
• SPMTs almost always work at SPE mode for IBD events and are expected to have almost zerodynamic range, hence virtually no non-linearity, thus providing a linear reference to LPMT; 25600 3’’ PMTs contracted to HZC, the production and bare tests are done, test after potting is ongoing;
Parameters

Unit

Requirement

Data/Mean

Detection efficiency(QE*CE)%>22(Mean>24)

24.9

HV@2*106 gain

V900-1300

1113

SPE resolution%<45(Mean<35)

33.2

P-V ration>2(Mean>3)

3.2

Dark Rate@0.25P.E.

<1.8K(Mean<1K)

512

SPE TTS(FWHM)

ns<53.7

QE non-uniformity%<114.9Effective Diameter of cathodemm>74(Mean>76)

77.2

Spectral response range%

QE320>510.2

QE550>5

8.6

3’’ PMTs
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Status : Top Tracker
 The top tracker(TT) precisely measure the muon tracking and provide Reusing the plastic scintillators from OPERA Target Tracker ;6.7 m

valuable information for cosmic muon induced background study;• 62 modules covered half of the top area;• 3 TT layers spaced by 1.5 m ,each layer have x,y readout; New electronics cards being designed to account for

100× higher radioactivity from rock in JUNO site ; The plastic modules are already at JUNO site;• No significant aging observed;
1.5m

JUNO Site (Mar 2019)17

Status : Water Cherenkov Detector
 A pool filled with 35 ktons of ultrapure water andinstrumented with 2400 MCP-PMTs to form the water
Cherenkov detector; Muon tagging efficiency is ~99.5%;
 Fast neutron background ~0.1/day; Water System:• Radon in water for JUNO prototype :< 10mBq/m3;• Calculation results show 20℃< Twater <22℃；

Temperature distribution

Radon measurement system

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Status : Calibration system The calibration system need to accurately address both the non-uniformity and non-linearity in the detector energy
response ; Energy scale uncertainty < 1%; Four complementary subsystems:• 1-D: Automated calibration unit(ACU);→ Scan the central axis;• 2-D: Cable loop system(CLS);→ Scan vertical plane;• 2-D: Guide tube calibration system(GTCS);→ Scan CD outer surface;• 3-D: Remotely operated vehicle(ROV);→ Full detector scan; Radioactive Sources:• γ、e+、n sources•

137Cs、 54Mn、60Co、 40K、68Ge、241Am-Be，241Am-13C ;19

Status : JUNO-TAO
 Taishan Antineutrino Observatory (TAO), a ton-level, highenergy resolution LS detector at 30m from the core, asatellite experiment of JUNO;
 To measure the fine structure of the reactor neutrino
spectrum, and eliminate the model dependence of JUNO

MO determination;
 TAO will be located at Taishan nuclear power plant;• 4.6 GWth in operation;• Spacious room at 10 m underground;• ~30m horizontally from core; Event rate: ~2000 IBD/day; Energy resolution: ~2%@1MeV；
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R&D status : TAO
 Target:• Gd-LS, 2.6 ton in total and 1 ton fiducialvolume; Detector:• Gd-LS + Acrylic + LAB + SiPM;
 Full coverage with SiPMs, PDE>50%

 Light yield: 4500 P.E./MeV; Operated at -50 Centigrade (SiPM darknoise); A 1:1 prototype is under construction andit will be tested without full SiPM;
 TAO is expected to start operation in 2022;
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R&D status : Civil construction Blasting completed on Dec. 30, 2020 ; We are in the period of transition from civil
construction to experimental installation;
Entrance

Surface building

Experimental hall

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Milestones & Schedule

Collaboration 20142016
• PMTproduction
2015
start
• PMT production• CD partsline setup
production• CD parts R&D
2014
start
• International • Civil construction• Yellow bookstart
collaboration
publishedestablished;

2017• PMT testingstart• TT arrived

2018• PMT potting• Startdelivery of
surfacebuilding• Startproductionof acrylic
sphere2021-2023• Detector
installation,• Detector
2020ready for• Civilconstruction data taking
completed• Electronics
massproduction

Neutrino
detected23

Summary JUNO: Rich neutrino physics prospects• Determine MO with 3-4σ with 6 years data;• Measure the neutrino oscillation parameters sin2 2θ12, ∆m2 21, and |∆m2 32| to a precisionof better than 0.6%;• Study neutrinos from supernova、the Sun、the Earth;• …..;
 The detector: A massive LS detector with excellent energy resolution• The largest acrylic sphere ever constructed;• 20 ktons of highly transparent LS;• Instrumented with 20000 20’’ PMTs and 25600 3’’ PMTs;• 4 calibration subsystems;• Reference measurement of reactor neutrino energy spectrum with TAO; Experimental installation will start soon, data taking expected to start in 2023 .

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Thanks for your attention!

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