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JUNO Detector Design &

Status

Zhimin Wang

(IHEP)

On behalf of the JUNO collaboration

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Outline

 JUNO

 Detector & Physics

 Few updates

 Progress

Civil construction

Production

 Installation

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Overview of JUNO

Jiangmen Underground Neutrino Observatory

Experiment Daya Bay Borexino KamLAND JUNO Liquid scintillator [tons] 8 x 20 ~300 ~1,000 20,000

Photocathode coverage [%] 12 34 34 75+3

Eff. Light Yield [p.e./MeV] ~160 ~500 ~250 ~1345

Energy resolution [%] ~8.5 ~5 ~6 ~3

Energy calibration uncertainty [%]

0.5 1 2 <1

Daya Bay

JUNO

~3%/ 𝑬 𝑀𝑒𝑉 energy resolution with huge LS target volume

arXiv:2104.02565v2 [hep-ex] 13 May 2021 Accepted by PPNP

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Acrylic Sphere : Φ 35.4 m

Stainless steel lattice shell : Φ 40.1 m

Water pool : Φ 43.5 m

P o o l d ep th : 4 4 m

Calibration house Central detector:

 Steel structure

 Acrylic sphere

 20 kton LS

Top tracker

PMTs:

 17612 20” HQE PMTs

 25600 3” PMTs

 75%+3% coverage

Water pool veto:

 35 kton pure water

 2400 20” HQE PMTs Earth magnetic shielding coils:

 For 20” PMTs

 Double coil system

JUNO Detector system

~700m

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JUNO collaboration 665 members from 77 institutes

15_thCollaboration Meeting, January 13-17, 2020, GXU, Nanning

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Physics with JUNO

• Neutrino mass ordering

• Precise measurement of Neutrino mixing parameters (better than 1%)

• Addressing many important topics in neutrino and astro-particle physics

Talk 169, “JUNO Oscillation Physics” by Jinnan Zhang Talk 273, “JUNO Non-oscillation Physics”, by Giulio Settanta

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Reactor neutrino detection

• Two of Taishan reactor cores will not be built

• Neutrino flux reduced 25%

• Experimental hall shifted up by ~60 m

• Cosmic muon flux increases by 30%

• Optimization of the antineutrino selection

• Live time improved from 83% to 93% to similar background level with minimization the dead time after the muon veto

• Higher 20-inch PMTs photon detection efficiency

• 27% to 29%

• More realistic PMT and liquid scintillator optical model

• Better understanding on the energy non-linearity

• Combined analysis of the TAO and JUNO detectors

Few updates w.r.t JPG 43, 030401 (2016)

Neutrino Physics with JUNO, arXiv:2104.02565v1

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Production of JUNO central detector (CD)

The top of acrylic sphere

Panel machining & node bonding

1 ppt requirement for U/Th/K

arXiv:2107.03669

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

Acrylic panel and lift structure

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Central Detector installation strategy

Self-Lifting test

Pre-assembly of the Installation platform

Acrylic sphere installation test with installation platform

Steps on platform

Platform carton

Anchor installed in

water pool

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Stainless steel structure

Top part Nodes

Embedded anchors in WP Welding supporting legs with its base plate

Supporting legs

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PMTs

 Two sizes of PMTs will be used to fully (~78%) cover CD;

• 17612 20’’ PMTs for CD (~75%) + 2400 20’’ PMTs for Veto;

• 5000 HPK dynode PMTs + 15000 NNVT MCP PMTs

• All delivered and qualified now:

• average PDE ~29% for CD (required/aimed ~27%)

• 25600 3’’ PMTs (~2.7%);

• Produced and tested

 Waterproof potting

 Will finish in this month for 20” PMTs

 Implosion protection;

 Production/assembly/installation going on

 Photon detection efficiency (PDE) will be further corrected for

testing system aging

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Veto Systems

Active and passive shielding for CD

Water Cherenkov Detector

 Shield ambient radioactivity and neutrons induced by cosmic rays

 Fast neutron background ~0.1/day;

 Veto muon induced backgrounds

 2400 20” MCP-PMTs

 35 kton ultra pure water with circulation

 Radon in water for JUNO prototype: < 10 mBq/m

³

;

(arXiv:2107.03669)

 Thermal Uniformity Calculation 20 ℃ < T

_water

<22 ℃ ；

 Muon Efficiency > 99%

Top Tracker (TT)

 Precise muon tracking

 The TT will cover 1/3 of all atmospheric muons passing through the CD (60% top of WP)

 Recycling the plastic scintillators from OPERA Target Tracker

 New electronics cards designed to account for 100 x higher radioactivity from rocks at JUNO site

6. 8 m

Top view

1.7m

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TAO

Taishan Antineutrino Observatory, A satellite experiment of JUNO

 A 1:1 prototype is under construction and it will be tested without full SiPM;

 TAO is expected to start operation in 2022;

 ~30 m from a Taishan reactor core (4.6 GW)

 10 m underground

  ~2000 IBD/day

 Physics goals:

 Precisely measure reactor antineutrino spectrum

 Provide a model-independent reference spectrum for JUNO’s NMO determination

 Reactor monitoring and safeguard

 Search for new physics

 Target:

• Gd-LS, 2.6 ton in total and 1 ton fiducial volume;

• Ton-level Gadolinium-doped LS at -50 °C

 Detector:

• Gd-LS + Acrylic + LAB + SiPM;

• Full coverage with SiPMs~10 m²SiPM with PDE>50% and >90% coverage

• Effective Light yield: 4500 P.E./MeV Energy res. : ~1.8% / 𝑬 𝑀𝑒𝑉

TAO CDR, arXiv:2005.08745

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Civil construction progress

Surface Buildings

• Power supply equipment in position

• Utility rooms completed

• Ventilation pipes and equipment installation are in progress

5000 ton LS tank

Entrance Computing room

Now

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Water pool status

Transportation Tunnel

Bird view Bottom view

Bird view with crane & water

lining

Now

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 Installation finished

 Filling

 Testing

JUNO Timeline

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Summary

• Vast program in particle physics & astrophysics

• Probing the neutrino oscillation mechanism at unprecedented precision

• Updates to the reactor neutrino detection

• Water pool civil construction completed

• Production/assembly/installation of Detector components going on

• Detector construction to be completed next year (2022)

Talk 169, “JUNO Oscillation Physics” by Jinnan Zhang Talk 273, “JUNO Non-oscillation Physics”, by Giulio Settanta Poster 142, “The JUNO OSIRIS detector” by Tobias Sterr

Poster 244, “Characterization of the JUNO Large-PMT readout electronics” by Beatrice Jelmini Poster 172, “Energy Response Model for JUNO Experiment” by Miao Yu

Poster 290: “Detection of Core-Collapse Supernova Neutrino at JUNO” by Xin Huang

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Thanks for your

attention!

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Backup

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Status : Small PMT

Parameters Unit Requirement Data/Mean

Detection efficiency

(QE*CE) % >22(Mean>24) 24.9

HV@2*10⁶gain V 900-1300 1113

SPE resolution % <45(Mean<35) 33.2

P-V ration >2(Mean>3) 3.2

Dark [email protected]. <1.8K(Mean<1K) 512

SPE TTS(FWHW) ns <5 3.7

QE non-uniformity % <11 4.9

Effective Diameter of cathode mm >74(Mean>76) 77.2

Spectral response range % QE320>5 10.2

QE550>5 8.6

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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 planes;

• 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

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Liquid Scintillator

LS recipe for Daya Bay

 JUNO LS recipe:

LAB + 2.5 g/L PPO + 3 mg/L Bis-MSB

 Higher light yield; more transparent!

 Attenuation length: >20 m @ 430 nm

Online Scintillator Internal Radioactivity Investigation System (OSIRIS)

Liquid scintillator

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LS recipe from Daya Bay

Liquid scintillator (LS) recipe:

• 2.5 g/L PPO + (1-4) mg/L bis-MSB

A pilot LS purification

system at Daya Bay for R&D Low radioactive backgrounds:

• 10 -15 g/g for neutrino mass ordering determination

• 10 -17 g/g for solar neutrino detection Attenuation Length: > 20 m @430 nm

• Improve raw materials and production process

• Purification systems (Al 2 O 3

Filtration column, water extraction, gas stripping)

Online Scintillator Internal Radioactivity Investigation System (OSIRIS)

 Low radioactive backgrounds:

10

^-15

g/g for neutrino mass ordering determination;

10

^-17

g/g for solar neutrino detection

TAUP2021，9/1，2021 Zhimin Wang on behalf of JUNO collaboration 22

Pls. refer to Poster by “The JUNO

OSIRIS detector” by Tobias Sterr

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Electronics