Status of JUNO Liquid Scintillator

Boxiang Yu on behalf of JUNO LS group

FroST16 @Fermilab; 2016-3-191

• Collaboration → June 2014• Civil engineering → end 2014• Data taking → 2020

JUNOJiangmen Underground Neutrino Observatory

2

What will JUNO get?

3

AS: Acrylic sphere; SSLS: stainless steel latticed shell

Central detectorAcrylic 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

Electronics

Filling +Overflow

4

Detector Vessel (Central detector)

20 ktons LS for JUNO detectorRequirements for JUNO LS: High light yield: ～1200 p.e./MeV Long attenuation length: >22m Low radio-impurity: 238U,232Th <10-15g/g 40K <10-16g/g

The most important thing is the purification of LAB/LS

JUNO LS requirement

5

JUNO-LS production flow chartPreliminary design

20kton LS will be purified-LS A.L. increased by Al2O3 column ;-Distillation, water extraction and steam stripping willbe used to reduce the radiation background of JUNO LS;

LAB A.L. : 13m->25m

6

3g/l PPO

LS recipe experiment result

Preliminary Result

• Recipe: LAB + PPO + bisMSB• The PPO concentration: 3g/l PPO; (Preliminary)• The Bis-MSB concentration is still undecided, it will be decided

after pilot plant experiment;• These result based on small size detector(Φ5cmX12cm)；

PPO concentration

Bis-MSB concentration

7

8

FLuors for JUNO LS

Small column optical purification

Experiment motivation：• Compare the different filtration material, such as active carbon,

resin and Al2O3;• Al2O3 purification ability, one volume Al2O3 can purify 10 Volumes

LAB？20BVs？ Or 30BVs？) (BV is bed volume, volume of AL2O3);

9

LAB/LS Purification experiment

Small size Experiment setup

Compare Al2O3 with Silica geland active carbon

Compare Al2O3 with resin

Al2O3

Al2O3

Filtration material contrast experiment

The result show: After several times contrast

experiment, Al2O3 is the best selection;

The different Al2O3 has been tried and the best company has been found;

10

Special LAB (A.L.= 15m ) and Commercial LAB (A.L.= 5m )

So the quality of raw LAB is very important for opticalpurification；

One volume AL2O3 can purify about 35 volumes for special LAB;

11

A.L.@430nm

The change is little. A.L.@430nm

The change is obvious.

Special LAB (After purification) Commercial LAB (After purification)

LAB contrast experiment

12

Small scale distillation tests: Fausto O. - Aldo R.

The distilled samples had showed betteroptical characteristics (both absorptionand emission) than the original notpurified ones. No deterioration of theLAB was noticed.

We also found a slight improvement inthe absorption spectra on the NanjingLAB pre-purified by Al2O3 column

Main distillation parameters:- Pressure: 0.4 mbar (very low -> T ≈ 110°C)- Claisen condenser (30 cm)- Vigreux column (15 cm – internal reflux)- System to collect different distillate fractions

280 320 360 400 440 480 520 560 600

0.0

0.8

1.6

2.4

3.2

4.0

350 400 450

0.00

0.06

0.12

abso

rban

ce

/ nm

abso

rban

ce

/ nm

before distillation

after distillation

13

Small scale distillation tests: Fausto O. - Aldo R.

Distillation tests: absorption spectra in a 10 cm-path quartz cell on the distilled Nanjing LAB pre-purified by Al2O3

A small-prototype• Radon was loaded to LS, then

LS purified by water extraction prototype;

• Water extraction plant can remove 238Th, 232U and 40K.

• Measure the purification efficiency at different conditions, and optimize the parameters.

Parameters:Flux Rate: 1~2L/hDisc Series: ~25 stages

Small scale water extraction test

14

Water extraction prototype experiment result

• The experiment result show that the purification efficiency can reachto 85% at room temperature (Saving underground power).

15

Water Extraction temperature result

Pilot plant of JUNO LS

DYB AD

16

Four purification system will be tested (Al2O3 column, distillation,water extraction and steam stripping);

Flow rate is 100～150 L/h; Every system will checked respectively , then the purified LS by

whole system will be filled and checked by DYB AD detector;

JUNO Pilot plants Hall (DYB LS Hall)

17

Distillation

Water extraction

Al2O3 column

Steam stripping

3D Design

Al2O3 column

Purified LAB tankControl Box

LAB and Al2O3 Mixing tank

AL2O3 column pilot plant

System Specification：Full size prototype；Column H:D=5:1；Column Diameter:500mm；Column Height:3000mm；Two stage Filter:1um filter +200nm filter (or 50nm filter)

18

Al2O3 column plant is based onthe “absorption” technique toremove optical impurities andincrease the A.L. of LAB

19

Distillation pilot plant

Distillation pilot plant main parameter:• Remove heavy metal, improve transparency• Flow rate 100 l/h (20 m3 in less then 10 days)• 6 physical trays• 1-2% adjustable bottom column discharge• High reflux rate (nominal 25%)• Be installed in this month

Process parameters

High[m]

Diameter[mm]

N°TraysPressure[mbar]

Temperature[°C]

Scint. Flux[l/h]

Scint. Reflux[l/h]

Max Gas flow

[kg/h]

Distillation 4 250 6 60 220 100 25-50 1

item Parameter

Flux Rate 170 L/h

Diameter of column 150mm

Height of Column 3.5m

Speed 0~200r/min

Paddle Stages 27

Physical trays >5

Temperature RT~800C

*We hope the purify efficiency is 85% at room temperature, and can reach 90% at 800C (for 212Pb).

Water extraction Pilot Plant

20

Water extraction pilot plant is the prototype. Theefficiency of removing 238U, 232Th and 40K will be gotten.It will be installed in next month.

21

Steam Stripping pilot plant

Stripping plant remove the impurities : Ar, Kr and Rn.Water steam can avoid to use huge quantity ofnitrogen in underground (safety).High temperature (100 °C) for higher column efficiency(low LAB viscosity)

• Partial vacuum (around 300 mbar)• Both steam and nitrogen stripping could be tested

in the plant

Process parameters

High[m]

Diameter[mm]

N°TraysPressure[mbar]

Temperature[°C]

Scint. Flux[l/h]

Steam Flux[g/h]

Gas flow[g/h]

Stripping 5.5 60Structured packing 300 100 100 250 250

- The nitrogen purification pilot plant developed; it will supply the high pure nitrogen for nitrogen blanket of pilot plant;

- It can be used as stripping gas (Nitrogen Stripping);

High pure nitrogen system

-Low background CarboACT active carbon was used;

LTA technology

22

Design Drawing Pilot plant

JUNO LS in DYB AD (Antineutrino Detector)

30 days data

The purified LS will be filled in DYB AD, AD will be used to checkthe Pilot plant purification result, including LS optical quality andradiation background;

The detection limit of 238U and 232Th is 10-15 g/g for DYB ADdetector from 30 days data;

Simulation result

23

Rayleigh scattering measurement

Rayleigh Scattering in LS is considered to be caused by thefluctuations and random orientation of molecules within asufficiently small volume.

With Rayleigh scattering taken into account, more photons can be detected by PMTs in the dark zone.

24

Rayleigh scattering is measured under ESC(Einstein-Smoluchowski-Cabanaformula) model. Four different experimental measurements have beenperformed. The results are consistence with each other in one sigma.

Model independent experiments are ongoing in JGU, WHU and UCAS.

Rayleigh scattering result

25

Milestones of JUNO

Start end

1 Underground lab construction 2015.1.1 2018.2.23

3 CD & water poll equipment installation 2018.2.28 2019.3.1

8 PMT testing 2017.4.4 2019.1.30

10 CD & VETO PMT installation 2019.3.4 2019.7.1

11 Readout electronics design finalized 2017.1.2 2017.5.31

13 LS purification system installation 2017.10.15 2018.12.25

15 CD & water pool cleaning 2019.8.1 2019.9.1

19 AD & VETO water filling 2019.9.4 2019.11.1

20 LS filling 2019.11.4 2020.2.3

21 Test run 2020.2.4 2020.5.4

26

• Huge LS detector: -20 ktons with precise energy resolusion:3%/sqrt(E)

• Transparent LS: attenuation length over than 22m

• Low radio-impurity: 238U,232Th <10-15g/g 40K <10-16g/g

• Five pilot plants have been completed, pilot plantsexperiment will be completed in 2016

• LS filling in end of 2019 and taking data in 2020

Summary

27

28

Thanks!

Backup

29

30

31

32

•UV-Vis measurement: IHEP, University of Perugia and INFN–Commercial instruments, small amount of samples, rapid measurement–Relative measurement–Difference caused by different instrument

UV-Vis measurement

Characterization and physical property study

33

Hardware setup：• LAB tube length 1.8m;• Wave length:430nm±5nm;• Systematic error: ～2m@20m;

Fiber

Amplifer

Pulse generator

HV Digitizer

Len

Filter

LED

PMTs

Electric platform

Stainless steel tube

Stainless steel tank

stepper motor

Check the AL2O3 columnpurification ability;

LS A.L. measurement system

34

35

ERS and Tyvek films Light out VS Bis-MSB

concentration

反射率

0 2 4 6 8 10

0.8

0.9

1.0

1.1

1.2

1.3

Tyvek

ESR

Concentration of Bis-MSB

rela

tive

va

lue

To measure isomers of LAB To measure impurities in LAB

–More important, but need complicated pretreatment of LAB samples before sampling–To many impurities which made the pretreatment very difficult and unstable: Naphthalene drivatives, Diphenyl drivatives, Aldehyde, Alcohol, Ketone, Ester, …–The most possible optical impurity in Nanjing LAB could be Fluorene–LAB samples from different vendors have different impurities

GC-MS measurement at IHEP

37