RENO Liquid Scintillator R&D
Introduction
Gd-LS R&D
Purification
Summary and plan
Daejung Kong (KNU)
KPS Spring Meeting, April 19, 07
경북대,경상대,동신대, 부산대, 세종대,
서울대, 서울시립대, 성균관대,
전남대, INR/IPCE (러시아)
Liquid Scintialltor for RENO
Gadolinium
Large neutron X-section, BKG rejection (coincidence)
Liquid Scintillator
High light output, good optical properties,
Long term stability, H/C, Radiopurity
Core component
Target
- LSc + Gd
Gamma catcher
- LSc
Buffer
- Non Scinti.
Veto
- Water
Shielding
e-
e+
νe
p
γ(0.511MeV)
prompt signal
Delayed signal
n
30μs
γ
γ
Gd
γ
γ(0.511MeV)
γ
å Eg ~ 8 MeV
Gd+Liquid Scintillator R&D
 Liquid Scintillator의 일반적 구성 물질:
Aromatic
PC(Pseudocumene),
PXE, LAB
Oil
Mineral oil, Dodecane,
Tetradecane, LAB
Fluor
WLS
PPO,
BPO
Bis-MSB,
POPOP
Gd-compound
0.1% Gd compounds
with CBX or BDK
 Liquid Scintillator R&D에서 수행하는 사항들:
- 구성물질의 조합과 배합 비율 결정
- 빛 방출량 측정
- 투광도 및 흡광도 측정
- purification system
- 주기적 측정에 의한 장기적 안정성 검사
- 변색 여부 검사
- 아크릴의 거부 반응 여부
2007 KPS spring Meeting
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Lesson and R&D about Gd-LS
Gd loading is a key issue
Chooz
Palo Verde
Gd
Gd(NO3)3
Gd2O3
Loading
Methods
Dissolved in hexanol + LS
Converted to carboxylate + LS
Light
degradation
Remarks
0.4 % / day
Unstable Turned Yellow
0.03 % / day
Stable  still usable
Gd loading is not trivial
Experienced Russian Group (INR) joined
 6 months stable Gd-LS
R&D with INR
2007 KPS spring Meeting
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Gd compound structure
Carboxylic acids:
H
R
b-diketonates:
O
C
R
C
O- H+
H
C
GdCBX
R
C
O
GdBDK
O
O
O
R
O
O
O
C
R1
H
CR2
O
3+Gd
HC-
O
O
O
R2
R
R2
O
O
R1
C
O
R2
Gd3+
C
CH2
2007 KPS spring Meeting
CH
R1
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Liquid Scintillator R&D 현황
R&D
Safety와
환경문제
Domestic
Availability
LAB100
RENO/Daya bay
Much less
toxic
YES
Inexpensive, 환경 친화적
PC20Dod80
Daya Bay/RENO
toxic
NO
Expensive
PXE20Dod80
Double Chooz
Less toxic
NO
Unstable  claimed by Daya bay
PC20MO80
PC40MO60
Palo Verde
Chooz
toxic
Available
2007 KPS spring Meeting
Remarks
Components?, purification
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RENO Gd (un)loaded LS R&D 현황
Optimization of Fluor and WLS
Optical properties (absorption,..)
Measurement of Gd concentration
purification (transparency, radio-purity)
Measurement of LS components
Light output - Nitrogen flushing effect
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Optimization of PPO, bis-MSB Concentration
Solvent : LAB
1g
2g
3g
4g
5g
6g
7g
10g
20g
PPO
PPO
PPO
PPO
PPO
PPO
PPO
PPO
PPO
 Purified LAB(100) + varying PPO
 PPO 3g/l 일 때, LY saturation
0mg/l
10mg/l
20mg/l
30mg/l
40mg/l
50mg/l
60mg/l
100mgl
200mg/l
 LAB100+PPO3g/l+bis-MSB30mg/l
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LAB(이수화학) 흡광도[Abs] 조사
 Beer-(Lamvert-Bouguer) law
 l = 0.4343 (L/(A420-Amin))
L: cell path length
A: absorption at 420nm
정제방법(Al2O3
adsorption)
정제 전
정제 후
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Performance of Gd in PC & LAB
Absorption spectra
Light output spectra
Gd loaded
Gd unloaded
100%
82%
96%
 LAB has lower optical absorption, better attenuation length
 100% LAB and PC have similar light outputs
 We got similar results with BNL & Daya Bay experiment
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Gd 농도 측정 방법
EDTA
Indicator
GdLS
Buffer solution
(PH>5)
① PH> 5에서 Gd은 EDTA와 반응도 높다
Gd
buffer solution
(PH>5)
측정 결과
② EDTA는 indicator와 반응해, 보라색에서
노란색으로 색깔 변화
indicator
buffer solution
③ VEDTA * CEDTA = Vsample * Csample
Sample
Composition
(ligand)
[Gd](%)
Remarks
첨가물
1
*3HR
0.109
HR(0.92m)
2
*3TBP
0.108
TBP(0.5m)
3
*2TOPO
0.118
TOPO(99%)
4
*3TOPO
0.110
TOPO(99%)
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최종 샘플 흡광도[Abs], latt, 농도 조사
적정횟수 Gd Concentration (%)
Abs
1
0.096
2
0.096
3
0.094
Note
 LS관련 약품을 살 때는 모두
고순도를 구입해서 사용해야
(특히, PPO, ligand)
 If not, additional purification will
be needed
2007 KPS spring Meeting
측정
Attenuation
length l(m)
1
5.65
2
6.18
3
6.19
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Attenuation Length of different solvents
before/after purification
정제 전(m)
정제 후(m)
PXE
1.0
1.3
Dodecane
15.2
16.2
PC
5.9
8.2
MO
9.7
N/A
LAB (batch1)
9.5
15.2
LAB (batch2)
7.7
14.7
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Transmittance of two different batch samples of LAB
B1
정제 전후 차이 없음
정제 전
B1 > B2
투광도: batch에 따라
다소 차이
2007 KPS spring Meeting
B2
정제 후가 better
정제 후
B1 = B2
투광도 batch에 무관
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Optimal ratio of LAB and Alumina for purification
- Optimization
• Find optimal ratio of LAB and Al2O3
• Using column adsorption method, take purified LAB for each time, naming
as batch1, batch2,… total 10 batches.
• Measure the absorption spectrums and calculate the attenuation lengths
(at 420 nm) of each batch  1:5 (alumina : LAB)
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Radiopurity level in LS
Radiopurity level  10-13 g/g (Th, U, K) : Daya Bay/Double Chooz
S/N > 100 (DB, DC)
RENO rediopurity level 측정 : ICP-MS(기초과학지원연구소)
Mineral Oil
K [g/g]
Th [g/g]
U [g/g]
0.77x10-6
< 2x10-9
< 5x10-10
정제 방법 개선 후 정밀도가 높은 장비로 측정 예정
From Daya Bay TDR
2007 KPS spring Meeting
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Radiopurity level in LS
Radiopurity level  10-13 g/g (Th, U, K) : Daya Bay/Double Chooz
S/N > 100 (DB, DC)
RENO rediopurity level 측정 : ICP-MS(기초과학지원연구소)
Mineral Oil
K [g/g]
Th [g/g]
U [g/g]
0.77x10-6
< 2x10-9
< 5x10-10
정제 방법 개선 후 정밀도가 높은 장비로 측정 예정
From Daya Bay TDR
2007 KPS spring Meeting
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Measurement of LAB Component using GC-MS
LAB : (C6H5)CNH2N+1
Motivation : calculation of # of proton, H/C
Gas Chromatography (GC) with Mass Spectrometry (MS)
Gas Chromatography
Mass Spectrometry (MS)
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Measurement of LAB components
LAB : (C6H5)CNH2N+1
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LAB components with GC-MS
LAB : (C6H5)CNH2N+1
C16H26
7.17%
C17H28
C18H30
C19H32
27.63%
34.97%
30.23%
# of H [m-3] = 0.631 x 1029
H/C = 1.66
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Measurement of Mineral Oil components
* KF-50,KF-70 : 서진화학 M.O
KF-70
KF-50
Difficult to figure out Component of M.O
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Effect of Nitrogen flushing & purification
Light Yield
w/o N2 flushing
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w/ N2 flushing
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Effect of Nitrogen flushing & purification
Light Yield
100%
82%
96%
2007 KPS spring Meeting
N2 flushing
is crucial
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Summary and Plan
 Current Gd (un)load LS R&D Status
Investigation of Solvents, Fluors
LS mixing procedure developed
Purification method developed
Start Gd loading into LS with Russian Group
 Long term R&D Plan
Investigation of radiopurity
Developing mass production techniques (purification, filling, etc.,)
Long term stability R&D (Light Yield, optical properties)
Stability is the most important !!!
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