summary of gd+liquid scintillator 김수봉, 박정식, 이재승 ( 서울대학교 ) 서준석 (...
TRANSCRIPT
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 )