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BNL Gd-LS for theta-13. Minfang Yeh , Alex Garnov and Richard L. Hahn Chemistry, Brookhaven National Laboratory, NY. Daya Bay Collaboration, Beijing, Feb. 2006. History of Gd- loaded 1 and unloaded 2 LS. Scintillator Selection. high density chemical compatibility with acrylic - PowerPoint PPT Presentation
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BNL Gd-LS for theta-13
Minfang Yeh, Alex Garnov and Richard L. Hahn
Chemistry, Brookhaven National Laboratory, NY
Daya Bay Collaboration, Beijing, Feb. 2006
History of Gd- loaded1 and unloaded2 LS Lab Baseline Extractant Fluors
Univ. Of Sheffield1 -hydroxytoluene Tri-ethylphosphate Butyl-PBD + PPO
Palo Verde1 40% PC + 60% Mineral oil Carboxylate 4 g/L PPO + 100 mg/L bis-MSB
CHOOZ1 50% Norpar-15 (paraffinic liquid) + 50% IPB (isopropylbiphenyl) Hexanol 1 g/L p-PTP + Bis-MSB
MPIK1 20% PXE + 80% DodecaneBeta dikitonate
orCarboxylate
6 g/L PPO + 20 mg/L bis-MSB
Eljen1 Anthracene or PC Unknown 3 g/L PPO + 0.3 g/L POPOP
Bicron1 PC or Mix of PC+MO Unknown unknown
Borexino2 PC No need 1.5 g/L PPO or p-TP+ bis-MSB
KamLAND2 20% PC + 80% Dodecane No need 1.52 g/L PPO
BNL1
2001: M-LS for LENS
2003: Gd-LSSelected scintillators
TOPO, alcoholor
carboxylateSelected wavelength shifters
Scintillator Selection• high density • chemical compatibility with acrylic• high light yield and long attenuation
• high flash point• low toxicity• low cost• load organo-metal complex?
Fill in the blanks?Gd
Loading d (g/cm3) UV Abs.430 before/after
Abs at 260 nm n20 Light
YieldH atoms‡ per c.c
Flash Point
PC
PCH
DIN
PXE
LAB
Mineral Oil~C28
Dodecane
BNL M-LS Synthesis Systems
Extractant Gd form in LS Comparison
alcohols GdCl3 .6H2O
GdCl3 quickly dissolved in the mixture of alcohol and PC; low light yield and not stable possibly due to quenching effect and high vapor pressure .
P=O compounds
Gd(carboxylate)x.(Cl)y.(OH)z.(H2O)a .
(TOPO)b
high extraction efficiency; moderate attenuation length; not stable for long term (phosphorus might interact with other compounds; CHOOZ experience of NO3)
carboxylic acid
Gd(carboxylate)x. (Cl)y.(OH)z.(H2O)a
high extraction efficiency; long attenuation length; high light yield; very stable (>14 months for Gd-LS and over 2.5 years for In-LS since synthesis )
M-LS Characterization is important to optimize the synthesis
Analytical Facilities at BNL
L1/e (attenuation length) by 10-cm UV-Vis, dual-beam, blue laser system, new LED vertical.
Light Yield (S%)
[Gd3+] by colorimetric method
[RCOOH]total by acid-base titration
[RCOOH]free by IR
[Gd species]PC by IR
[H2O] by Karl-Fischer titrator
[NH4+] and [Cl-] by electrochemistry
O
O
O
O
O
O Gd
C
C
C
CH3
CH3
CH3
Inner-sphere complex
PlusOuter-sphere ligands: [H2O], [OH-], [NH4
+] and [Cl-]
Notes of M-LS Preparation
• Solvent-Solvent extraction vs. organo-metal solid dissolution.
• BNL has developed a series of chemical technologies that can be used to prepare M-LS (In, Yb, Gd, Nd) in large-scale production (~tons) for neutrino experiments.Refs: 1. BNL+Bell Lab, In-loaded LS for LENS; 2. BNL, Gd-LS for Theta-13 Reactor Experiment.
• High concentration (1~2%) of Gd-LS to be diluted at percent of interest on experimental site.
Attenuation Length Measurements
1. 1- and 10- cm cells in Shimadzu UV-1601 spectrometer (200 – 1100 nm)
2. 1-m horizontal cell, blue laser system (442 nm)
3. 2-m vertical pathlength, LED variable wavelength system (350 – 700 nm, BNL Chemistry + Physics)
under black lightunder room light
Fiber Collimator
New LED New LED for for
Attenuation Attenuation LengthLength
Splitter Cube
2.5 m
2.0 m
LED at ’sBeam Splitter
CCD or PMT
Air Vent
LabVIEW DAQ
LED Signal
Stability of Gd-LS in PC (10 cm cells)
The technology of loading Gd into PC and its mixture (with dodecane or MO) is mature; liters of different concentrations of Gd-LS have been produced and under stability QC for 1.5 years.
Do we have another choice?
PC has drawbacks of low flash point and chemical aggressiveness.
LAB from SNO+/++linear alkyl chains of 10-13 C atoms with a benzene ring; used primarily
for the production of biodegradable synthetic detergent
Boiling Point (oC) 275 - 307
Melting Point (oC) < -50
Flash Point (oC) 130
Vapor Pressure (mmHg) < 0.1 mmHg @ 20oC
Vapor Density (Air =1) 8.1
Solubility in Water Insoluble
Molecule Weight 233 – 237 g/mol
pH Not applicable
Viscosity 5 – 10 cps @ 20oC
Evaporation Rate (water =1) Not applicable
11
0
high light yield, high flash point, low toxicity, cheap an ideal scintillator for neutrino experiment
Optical of LAB after Staged Purification
Optical of ~1% Gd in LAB and in PC
• BNL has successfully loaded Gd into 100% LAB
• Gd-LAB has much better transparency at < 400 nm and at least ~50% improved optical transparency at 430 nm, compared to Gd-PC
430 nm
Stability of Gd-LS in LAB (10 cm cells)
The blanks were filled after X years…Gd
Loading d (g/cm3) UV Abs.430 before/after
Abs at 260 nm n20 Light
YieldH atoms‡ per c.c
Flash Point
PC Yes 0.889 0.008/0.002 2 1.504 1 5.351022 48 C
PCH Yes 0.95 0.072/0.001 1.7 1.526 0.46 3.721022 99 C
DIN Yes 0.96 0.040/0.023 >10 0.87 5.451022 >140 C
PXE Yes, but not stable 0.985 0.044/0.022 2.1 0.87 4.341022 167 C
LAB Yes 0.86 0.001/0.000 1 1.482 0.98 6.311022 130 C
Mineral Oil~C28
No 0.85 0.002 ~0.001 1 ~1.46 ~ 7.53 1022 215 C
Dodecane No (<20%) 0.75 0.001
~0.000 1 1.422 ~ 4.771022 71 C
Summary• We are capable of producing hundreds of liters of 0.1% Gd-LS for prototype
study in few months.
• Gd loaded in PC or LAB?
1. Samples of 0.2% Gd in mix’s of PC and dodecane are stable for hundreds of days (300 days for 20%-80%, 340 days for 40%-60%, and 430 days for 100%).
2. Samples of 0.2% Gd in LAB are stable over 3 months up to date
Need compatibility test and more stability data• Wavelength shifters (quantum yield & decay time) for selected Gd-LS need
to be finalized.
• Compatibility test of acrylic vs. organic solvent.
• Chemical assays to remove naturally occurring radioisotopes.
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