Summary of Gd+Liquid Scintillator

김수봉 , 박정식 , 이재승 ( 서울대학교 )서준석 ( 경북대학교 ) 유인태 ( 성균관대학교 ) 주경광 , 김선희 ( 전남대학교 )

9th RENO Collaboration Meeting at SNU

Oct. 10~11, 2008

RENO LS Subgroup Collaboration

주경광 ( 전남대 )

RENO DetectorBuffer with PMT Front view

Side view

RENO detector consists of four concentric

cylindrical containers.

384 PMTs

Liquid Scintillator at a Glimpse

• Transparency• High light yield• Long term stability• High radiopurity • Safety matter• Reasonable price• Massive quantity available

Base solvent For mixing FluorWave-length

shifter

PC, PXE MO, Dodecane PPO, BPO bis-MSB, POPOP

Base solvent + primary scintillating fluor + secondary wavelength shifter

Required Properties

General elements of Liquid ScintillatorEffect of wavelength shifter

Before

After

PMT sensitive regionPC is widely used for base solventfor its excellent transparency and fluor dissolution.

RENO Base Liquid Scintillator

PC(20%) + dodecane(80%) + PPO(3g/L) + bis-MSB(30mg/L)

• Gd-LS R&D with the Russian INR/IPCE group : Gd-LS stability: good for > 6 months• Performance study of various LS recipes : : light yield : Optical properties (transmission & attenuation lengths, etc.)• Development of purification system to enhance optical properties & reduce radioactive materials. : Al2O3 adsorption : Vacuum distillation : Water extraction, etc• Long-term stability test• Reactivity test with acrylic • Study of Linear Alkyl Benzene(LAB) for replacing PC.

Purification with Al2O3

Before

After

Transparency can be increased by purification.

LAB(Linear Alkyl Benzene)

CnH2n+1-C6H5 (n=9~14)

PC LAB

Molecular formula C9H12 CnH2n+1-C6H5

Molecular weight(g/mol) 120.19 233~237

Flash point (°C) 48 130

Density(g/ml) 0.89 0.86

Compatibility(acryllic) Negative, need diluent Test in progress

Cost Moderate Cheap

Fluor dissolution Very good Moderate

Domestic availability Abroad Available

etc Harmful odor Colorless & odorless

LAB

n Percent(%)

9 0.47

10 9.7

11 33.85

12 34.72

13 20.83

14 0.43

GC-MS result of LAB

Light Yield Comparison

4 main component

Optimization of PPO & bis-MSB Concentration

Light Yield Measuremen

t

LY saturated when PPO 3g/L and bis-MSB 30mg/L

Bis-MSB

PPO

Optimization of PPO & bis-MSB Concentration

Light Yield Measuremen

t

LY saturated when PPO 3g/L and bis-MSB 30mg/L

Bis-MSB

PPO

Problems reported

CHOOZ 실험에서- 5t 0.09% Gd-loaded scintillators - 변색문제 : Not stable (turned yellow after few months of deployment) ~250 일 경과 후 )- 출력감소 문제 : Degradation of its optical properties. 즉 , very rapid decay of attenuation length 관측됨 . ~0.4% degradation/day

또한 , Palo Verde 실험에서도 비슷한 결과가 보고됨- 12t 0.1% Gd-loaded scintillators - Slight deterioration with time- ~0.03% degradation/day

Gd-doped Liquid Scintillator Chemistry

Gd -CBX

Precipitated Gd-CBX powder was filterated and rinse with 18MΩ water several times and dried in desiccator.

After filteration

Stored in bottle

Gd needs to transform to Gd-CBX for loading in organic phase

Gd-CBX precipitated

Reaction equation

RCOOH + NH3•H2O ->RCOONH4 + H2O3RCOONH4(aq) + GdCl3(aq) -> Gd(RCOO)3 + 3NH4Cl

FT-IR 에 의한 Gd-TMHA 성분분석

FT-IR(Fourier Transform Infrared Spectroscopy, 적외선 분광법 )

적외선을 시료에 주사하면 시료의 분자운동에 의한 적외선흡수가 발생하고 흡수된 적외선스펙트럼을 얻어 시료를 분석하는장치

만족 시켜야 할 조건

1. OH group 유무 - FT-IR 3200~3500 사이에 peak 나타남 .

2. Free acid peak 유무 - FT-IR ~1700 근방에 peak 나타남 .

3. Carboxylic peak 유무 - ~1420 & 1580 근방에 peak 나타남 .

4. Gd loading into LAB

Gd-(TMHA)3 powder 제조가 목적Gd-OH 는 불순물로 작용 .

이유

여분의 TMHA 가 남아있는 것 .물로 세척 할 때 씻겨나가지 않는다 . 불순물로 작용 .

Gd-TMHA 가 만들어 진것을나타내는 증거

성공적인 RENO 실험을 위해

Requirements for Gd-TMHA

결정 요인 : after reaction 의 pH 값

pH 7.4

pH 6.5

pH 6.2

pH 6.0After reaction pH ~ 6.0 이하로제작해야 OH peak이 보이지 않는다 .

Carboxylic-1420 & 1580

OH-3200~3500

Peak position

Free Acid-1710

OH peak

OH group

결정 요인 : 중화반응 시 남는 여분의 TMHA 의 유무

TMHA 과량

NH3 다량 과량

NH3 미량 과다

Almost 1:1

중화반응 시 NH3 양이 더 많아야 함

: pH > 7

pH ~5

pH ~7.2

pH ~7.5

pH ~9.7

Free acid peak

Free acid

R&D 결과- pH control 이 중요- After reaction pH ~ 6

After reaction pH 결정 요인- Gd 수용액 pH 4.5~5- 중화반응 pH > 7

8:8 Sample1

sample2

Sample3

sample4

sample5

Sample7

Sample10

sample13

GdCl3*6H2O N/A 2.0154 2.007 2.012 2.008 1.6088 2.403 2.0013 2.0072

Gd pH N/A 5 5 5 5 5 5 5 5

중화 pH N/A 8 7.5 8 7.5 7.5 7.5 7.2 7

After reaction

N/A 6.9 5.6 6.7 6.5 7.4 6.2 6.0 6.47

Purity ( 질산 )

122 102.8 95.7 102.7 98.7 97.5 95.7 93.2 94.2

Sample lists

OH group

OH group + 염 과다

Worst

Gd-TMHA Samples

Best sample

Sample 10 PH 배합이 가장 promising

Sample 10 LAB loading 적정 결과 : 2.81 g/L 까지 해봄

LAB 에 문제없이 loading 됨

Gd Loading in LAB

Reproduce

pH 6.0

pH 6.47

pH 6.83

Sample 10-1- LAB loading 적정 : 92.4%- 질산 적정 : 94.3%- LAB / 질산 = 0.98

Sample 10-2 비교 sample- LAB loading 적정 : 93.8%- 질산 적정 : 94.9%- LAB / 질산 = 0.99

Vol(L)

Flow Rate

Target

153 2 L/min

G.Catcher

1120 6 L/min

Buffer

6889 24 L/min

Flow rate to keep same level

GdLS200L

LS200L

MO200L Mockup

123

N2

N2

N2

AccumulateFlow Meter

Flow Meter

Magnetic Pump

Schematic Design of LS Handling System

for Mockup

• Mixing Tank+ Capacity : 200 L+ Material : P.E.

• 3 tanks for Target, Gamma Catcher and Buffer.• All tubing for liquid transportation is made from Teflon. • N2 purging with Ф6 Teflon tubing

MO 고순도 LAB

Production of LS for Mockup

• Baseline LS cocktail : – PPO(3g/L) + bis-MSB(30mg/L) + LAB

• PPO, bis-MSB 20 배 농축 일의 효율성증가• 1 회 200L LS 생산한 후 filling 시작예정

– LAB (190L) + 20 times concentrated LS (10L) : with circulation mixing method

– 20 times concentrated LS = LAB (10L) + PPO (600g) + bis-MSB (6g)

• 목표량 : 200L of LS / a day ( 총 4 일정도 소요 )

Summary

• LAB is promised material to replace PC, dodecane. (e.g. Optical properties, radiopurity, …) • Concentrations of PPO and bis-MSB for Liquid Scintillator are optimized.

• Light yield was measured in special dark box using Compton edge.

• Long term stability test will be carried out.

• Gd-TMHA 제작 R&D + Mock-up sample recipe 확정 . Reproduce & quality control 진행 중

• RENO 검출기를 위한 대량 생산 준비

• Mock-up 용 powder 준비기간 + R&D 끝나면 대량 생산 시작 + 하루 ~80g 생산 예정 ( 제작에 2 주 소요될 것으로 예상됨 )