The Jiangmen Underground Neutrino Observatory Liangjian Wen JUNO - - PowerPoint PPT Presentation

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The Jiangmen Underground Neutrino Observatory Liangjian Wen JUNO - - PowerPoint PPT Presentation

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The Jiangmen Underground Neutrino Observatory Liangjian Wen JUNO Neutrino Astronomy & Astrophysics Workshop, Nanjing University, Apr.17-18, 2016 JUNO Experiment Jiangmen Underground Neutrino Observatory 20 kton LS detector, 3%/

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SLIDE 1

The Jiangmen Underground Neutrino Observatory

Liangjian Wen

JUNO Neutrino Astronomy & Astrophysics Workshop, Nanjing University, Apr.17-18, 2016

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SLIDE 2

Yangjiang NPP, 17.4 GWth Taishan NPP, 18.4 GWth

53 km 53 km

Daya Bay NPP

700 m overburden

q12 osc. maximum

PRD 88, 013008 (2013)

JUNO Experiment

Rich Physics

  • Reactor neutrinos:

Mass hierarchy & Precision measurement

  • f mixing parameters
  • Supernova neutrinos
  • Geo-neutrinos
  • Solar neutrinos
  • Sterile neutrinos
  • Atmospheric neutrinos
  • Exotic searches

Jiangmen Underground Neutrino Observatory

  • 20 kton LS detector, 3%/ 𝑭 energy resolution

A multiple-purpose neutrino experiment

  • J. Phys. G 43: 030401 (2016)

(arXiv:1507.05613)

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SLIDE 3
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SLIDE 4

Cosmic muons ~ 250k/day

Atmospheric  several/day Geo-neutrinos 1-2/day Solar  (10-1000)/day

Neutrino Rates

reactor , ~ 60/day

700 m

Supernova  ~ 5k in 10s for 10kpc

20k ton LS 36 GW, 53 km 0.003 Hz/m2, 215 GeV 10% multiple-muon

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SLIDE 5

Reactor e signal and backgrounds

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Background Rate Uncertainties 30% 1% 100% 20% 50% Background Shape Uncertainties 5% negligible 20% 10% 50%

n e p

e

  

n + p  d + γ (2.2 MeV)

Neutrino Event: coincidence in time, space and energy τ  200 μs

Inverse- decay reaction:

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SLIDE 6

Ref: Y.F Li et al, PRD 88, 013008 (2013)

Relative Meas.

(a)Use

absolute Dm2 Ideal case 4s 5s

(b)Realistic case

3s 4s

Sensitivity on MH

Y.F Li et al

JUNO MH sensitivity with 6 years' data:

(a) If accelerator experiments, e.g NOvA, T2K,

can measure DM2

mm to ~1% level (b) Take into account multiple reactor cores,

uncertainties from energy non-linearity, etc

Ideal Core distr. DYB & HZ Shape B/S (stat.) B/S (shape) |Dm2

mm|

Size 52.5 km Real Real 1% 6.3% 0.4% 1% Dc2

MH

+16

  • 3
  • 1
  • 1
  • 0.6
  • 0.1

+ (4-12)

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SLIDE 7

Precision Measurement

Probing the unitarity of UPMNS to ~1%

0.16%0.24% 0.39%0.54% 0.16%0.27%

E resolution Correlation among parameters

Statistics +BG +1% b2b +1% EScale +1% EnonL sin2 θ12 0.54% 0.67% Δm2

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0.24% 0.59% Δm2

ee

0.27% 0.44%

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

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SLIDE 8

Precision Measurement

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  • Unitarity test of neutrino mixing matrix. (precision of s𝑗𝑜θ12is critical)
  • Narrow down the parameter space of the effective mass |mee| of

NDBD

  • Discriminate models of the neutrino masses and mixing.
  • Test if Δ𝑛13

2 + Δ𝑛21 2 + Δ𝑛32 2 =1

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SLIDE 9

Requirements on Energy Resolution

Impact to MH sensitivity

stochastic term constant term noise term

Generic form

  • 3%/ 𝑭 energy resolution

– LS att. length: >20m@430nm

Absorption 60 m + Rayleigh scattering 30 m

– PMT parameters

  • QE: >30%@430nm

(CE modeled in MC)

  • photo-coverage: >75%
  • charge resolution: <30%
  • QE non-uniformity: <20%
  • time resolution: <3ns
  • dark noise: <50kHz/PMT

Data validated Full MC (DYB&DC) JUNO 9

6 yrs

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SLIDE 10

20” MCP-PMT R&D in JUNO

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Evaluate both the PMT characteristics’ impacts on MH hierarchy and the cost. Finished 20” PMT bidding at end of 2015:

  • - 15000 MCP-PMT (China)
  • - 5000 Dynode-PMT (Japan)
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SLIDE 11

Liquid Scintillator

  • LAB+PPO+bisMSB (no Gd-loading)
  • Increase light yield

– Optimization of fluors concentration

  • Increase transparency

– Good raw solvent LAB – Online handling/purification

  • Distillation, Filtration, Water

extraction, Nitrogen stripping, … To be tested with Daya Bay detector

  • Reduce radioactivity

– No Gd, Less risk. Singles<~3Hz (>0.7MeV), with U/Th <10-15 g/g,

40K< 10-16 g/g

Linear Alky Benzene (LAB)

  • Atte. Length

@ 430 nm RAW (specially made) 14.2 m Vacuum distillation 19.5 m SiO2 coloum 18.6 m Al2O3 coloum 24~25 m

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water extraction Al2O3 column

Al2O3 Test

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SLIDE 12

Al2O3 column

LAB and Al2O3 mixing tank Pure LAB

JUNO-LS Pilot plant

  • Test the overall design of purification system at

Daya Bay. Replace the target LS in one detector

  • Quantify the effectivities of subsystems

– Optical : >20m A.L @430nm? – Radio-purity: 10-15 g/g (U, Th) ?

  • Determine the choice of sub-systems

– Al2O3 column, distillation, gas striping, water extraction

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Al2O3 column pilot plant installed in Daya Bay LS hall Distillation system Steam stripping system Distillation and steam stripping system (by Italian group). Be transported to Daya Bay at Apr/May

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SLIDE 13

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JUNO Layout

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Central detector Acrylic sphere+ 20kt Liquid Scin+ ~17000 20” PMT+ ~34000 3’’ PMT Water Cherenkov ~2000 20’’ PMT Top Tracker Calibration 43.5m D43.5m AS: ID35.4m SSLS: ID40.1m AS: Acrylic sphere; SSLS: stainless steel latticed shell Electronics Filling+

  • verflow

Pillar: ~100 Connecting bars: ~600

JUNO Detector Scheme

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SLIDE 15

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March, 2014 July, 2015 SS truss+ Acrylic sphere Balloon + Acrylic support+ SS tank

Acrylic sphere+ SS truss Balloon+ SS tank Acrylic sphere+ SS tank Acrylic module+ SS tank

Final decision: Acrylic sphere + SS truss

CD Option Selection

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SLIDE 16

Detector Dimension

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RLS=17.2 Tacrylic= 0.12m TwBuffer = 1.43 m TWP = 1.2m PMT mounting

  • n SS Struss

RCD-PMT = 17.82 + TwBuffer RWP = 43.5m

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SLIDE 17

Sensitivity vs. dimension

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Only consider the statistical impact on chi2 from accidental background: Divide LS into equal-mass-bin, calculate the c2 contribution from each shell, then

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SLIDE 18

Central detector Acrylic sphere+ 20kt Liquid Scin+ ~17000 20” PMT+ ~34000 3’’ PMT Water Cherenkov ~2000 20’’ PMT Top Tracker Calibration 43.5m D43.5m AS: ID35.4m SSLS: ID40.1m AS: Acrylic sphere; SSLS: stainless steel latticed shell Electronics Filling + Overflow

JUNO Detector Scheme

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SLIDE 19

JUNO Central Detector

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Acrylic sphere

  • ID:Ø35.4m
  • Thickness:120mm
  • Weight: ~600t

Acrylic panel

  • 21 layers + top chimney

+ bottom flange

  • ~260 pieces
  • ~560 connecting nodes

Stainless steel latticed shell

  • ID: Ø40.1m
  • OD: Ø41.1
  • Total Weight: ~600t

H-beam

  • 21 latitude circles: 400x300x12x18
  • 32 longitude circle: 500x300x12x18
  • ~100 Supporting legs
  • Connecting bar: Ø70

Supporting leg H-beam Connecting bar Connecting node

Connecting node

  • ~560
  • Connecting steel piece

inserted into acrylic

120mm acrylic wall Appended acrylic Steel piece

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SLIDE 20

Acrylic Sphere R&D

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The maximum stress of acrylic is concentrated at connecting nodes How to reduce the stress on acrylic node?

  • a. Lower the load on connecting bar
  • b. Improve the design of connecting node

Worst stress case: the total vertical load is ~2600t, ~560 connecting nodes will carry it

Type B

  • b. How to improve the node design
  • Optimize the structure of node
  • Two kinds of node for compressive area

and tensile area

High tensile strength Type A High compressive strength

spring Adjust the stiffness of some connecting bars

  • a. Lower the max load on connecting bar
  • Add the quantity of bar Add light block X
  • Improve the load distribution on bars

How to improve the load distribution on bars?

Acrylic stress is a critical issue for engineering design.

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SLIDE 21

Acrylic Sphere R&D

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Forming panel size: 3m x 8m x 120mm Prototype of spherical panel The problems of shrinkage and shape variation were resolved. Three companies had good practices. Acrylic divided into 200+ panels

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SLIDE 22

Prototypes of connecting node

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Another key point of acrylic sphere, ~500 nodes needed, production in acrylic company

1:1 Prototypes and strength test 1:4 Prototypes and strength test

Type A Type B

Purpose:

  • Compare the FEA and test result
  • Improve the structure design and bonding technology
  • Get the ultimate breaking capacity of connecting structure
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SLIDE 23

CLS GT

Calibration System

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Guide Tube ACU

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SLIDE 24

PMT arrangement

24 Coverage for different arrangement tries

The supper layer method is the best one, can get the highest coverage

20” PMT(~17000) 3” sPMT(~34000) Arranged between 20” PMTs

CD: 20 inch and 3inch PMTs were arranged on the steel structure

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SLIDE 25

PMT Readout

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Made the final decision last year

Put most of electronics underwater and sealed with BASE, HV together. Use the single CAT5+ cable to transfer data, hit, clock, power and trigger

Front part under-water Backend part- ”Dry” part

  • Needs to consider the integration and potting structure with PMT
  • Replacement under water is almost impossible, need high reliability of

potting, electronics and HV

Flash ADC of 1GHz Out of water

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SLIDE 26

PMT Potting

26 The conceptual design of JUNO PMT Potting

Status:

  • Conceptual design of the overall structure is finished
  • Study on potting sealants, cable sealing and the

thermo-conductivity is ongoing

  • 41 PMTs of 5 types were potted and used for JUNO
  • prototype. Obtained good experience

Potting requirement became higher

  • Base, High Voltage unit and the front-end electronics need to be potted
  • Working under 45m high-purity water;
  • 20 years lifetime
  • 0.5% failure rate for the first 6 years

Adhesive or oil Waterproof sealant

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SLIDE 27

SS cover Acrylic cover small holes Openings

PMT Implosion Protection

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  • A prototype of the protective cover is under design and test

upper cover: Acrylic lower cover: Stainless Steel

Protection requirement:

  • Protect PMT from chain implosion
  • ptical transparent : ~1% in light blocking
  • least possible impact on the coverage

Distance (m) Pressure (MPa)

Shock wave from bare PMT has been measured in JUNO conditions:

  • peak value is about 14 MPa @15cm from the glass shell
  • The shockwave decreases quickly for larger distance
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SLIDE 28

CD Prototype

Test the performance of various PMTs’ performances, the PMT potting, supporting structure, electronics, HV, reliability, etc.

H 20” MCP 20” HZC 9” H 8” MCP 8” 28

~1 m water tank

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SLIDE 29

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CD Prototype

Assembly finished at the end of 2015 Preliminary data shows: PMT water-proof potting works well PMTs perform well

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SLIDE 30

6.8 m

  • Cosmic muon flux

– Overburden：~700 m – Muon rate：0.0031 Hz/m2 – Average energy：214 GeV

  • Water Cherenkov Detector

– > 3.9 m water shielding, Radon: <0.2 Bq/m3 – ~1500 20”PMTs – 20~30 kton pure water, HDPE lining – Similar technology as Daya Bay (99.8% efficiency)

  • Top muon tracker

– Muon track for cosmogenic bkg rejection – Decommissioned OPERA plastic scintillator – Possibly w/ RPC

Veto Detectors

Top muon tracker Water Cherenkov Detector

Muon multiplicity at JUNO

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SLIDE 31

Compensation coils

  • Vertical

 17 pairs；central intensity：0.238Gs；  Diamter：43.3m；  current：11.73A；  Total cable length:16.5Km;  Horizontal

 15 pairs；central intensity：0.38Gs；  Diamter：43.3m；  current：10.32A；  total cable length：21.4Km；

  • Earth magnetic field in experiment site
  • Two direction coils systems

Ф41m uniformity: 94.0% Ф40m uniformity: 96.0% Ф39m uniformity: 97.0% Ф41m uniformity: 81.0% Ф40m uniformity: 94.0% Ф39m uniformity: 98.0%

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SLIDE 32

Project Plan and Progresses

  • Decided Central Detector Scheme: 2015.07
  • Finished PMT bidding: 2015.12 (production: 2016-2019)
  • Finish the engineering design of detector structure:

2016.07

  • Bidding for acrylic production: end of 2016
  • Civil construction: 2015-2017
  • Detector component production: 2016-2017
  • Build detector onsite: 2018-2019
  • PMT installation, Veto, cleaning, filling : 2019-2020
  • Data taking：2020

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SLIDE 33

Thanks!

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