Properties and QC of Some InLS by Refined Recipe

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Studies of Gd-LS in the U.S.A. (and the U.K.)

Richard L. Hahn Solar Neutrino/Nuclear
Chemistry Group (Z. Chang, M. Yeh, A.
Garnov, C. Musikas) BNL Chemistry Department
Low-Energy Antineutrino Workshop Cal Poly, S.L.O.
Brookhaven Science AssociatesU.S. Department of
Energy
March 15, 2004
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A Bit of History

• This RD begun a few years ago at BNL for LENS
  project, in collaboration with R. S. Raghavan
  and others.
• Purpose To synthesize metal-loaded liquid
  scintillator, M-LS, at relatively high
  concentration of M, 5-10 wt/wt.
• M serves as target for neutrino capture (CC
  interaction) to excited state in daughter
  nucleus, producing e- g ray(s) in coincidence.
• Low-energy Q-value makes M suitable to detect
  solar 7Be, pp, pep, CNO neutrinos.
• Studied M Yb(3) and In(3).
• Approach is to prepare metal-organic complex
  that is stable and
• soluble in LS.

Brookhaven Science AssociatesU.S. Department of
Energy
3
A Bit of History - Continued

• Organic complexing agents were carboxylic acids,
  RCOOH, and organophosphorus compounds, such as
  TBP, TBPO, TOPO.
• Need Long-term chemical stability (no
  precipitates or gels).
• Optical clarity, i.e., long attenuation
  length.
• High light production.
• Succeeded in preparing M-LS, mainly with In,
  that satisfied our needs. Use (6-carbon)
  carboxylic acid methylvaleric, HMVA.
• In principle, this method should work well with
  Gd(3) to make Gd-LS for reactor antineutrino
  experiment.
• Began Gd RD several weeks ago.
• Have preliminary results that are very
  promising.

Brookhaven Science AssociatesU.S. Department of
Energy
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Systems Tested for the BNL Gd-LS Synthesis
System Form of Gd Extractant Notes
BNLGd1 GdCl3.6H2O Dissolved in Ethanol ( PC) GdCl3 ethanol soln. mixed with PC. Not stable. Product Gd0.39, L_at_430nm434 cm, and S36.9
BNLGd2 GdCl3 .6H2O Dissolved in Propanol ( PC) GdCl3 propanol soln. mixed with PC. Not stable. Product Gd0.10, L_at_430nm434 cm and S57.0
BNLGd3 Gd(MVA)xCly similar to In-LS PC Get Precipitate in the Aqueous phase. Extractn. pH3.89. Gd-LS Stable, but Low Extractn. Efficiency. Product Gd0.28, L_at_430nm167 cm, and S58.7
BNLGd4 Gd(MVA)2.7 Cl0.3-x OHx (TOPO)0.3 TOPO ( PC) Aqueous and PC phases are clear. Extractn. pH6.63. Gd-LS Stable. High Extractn. Efficiency. Product Gd3.24, L_at_430nm543 cm, and S68.9
1,2,4-trimethylbenzene (pseudocumene, PC) is
used as the solvent for all the systems. L
attenuation length S Light Output relative to
100 PC.
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Purification of HMVA by Distillation
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Purification of Pseudocumene, PC
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Purification of Phenyl Cyclohexane, PCH
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Steps in Solvent-Extraction Synthesis of BNLGd4

• Prepare Aqueous Phase. Neutralize HMVA H2O
  with NH4OH solution. Product is NH4MVA.
• Purify NH4MVA.
• Add Organic Phase, PC TOPO, to the purified
  Aqueous NH4MVA solution.
• Purify Aqueous GdCl3 separately.
• Solvent Extraction. Add GdCl3 solution drop-wise
  into the two-phase NH4MVA PC TOPO system.
  White plume forms in the Aqueous Phase,
  disappears gradually as the Gd-MVA complex
  extracts into the Organic Phase. Two clear phases
  form at equilibrium. pH6.
• H2O Removal. Separate the Organic Phase and
  centrifuge it to remove any residual H2O (or pass
  through drying column).

Brookhaven Science AssociatesU.S. Department of
Energy
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The Chemical Composition of BNLGd4
Gd MVA Cl1 H2O TOPO PC2
wt. 3.24 6.39 0.23 0.22 1.90 88.07
Number per Gd 1 2.69 0.33 0.59 0.24 35.56
1 Chlorine content is estimated from the charge
balance of the Gd molecule. 2 PC is estimated
from the percentage of other components.
Analytical formula of Gd is estimated as Gd(MVA)
2.7Cl0.3-xOHx(TOPO)0.3
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UV Spectra of BNLGd4 Samples
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Attenuation of BNLGd4 Samples
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Light Yields of the BNLGd4 Samples
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Gd-LS From Different Labs
Lab Solvent Extractant Fluors
BNL 1,2,4-trimethylbenzene (PC) Tri-n-octylphosphine oxide 0.3 g/L BPO, 15 mg/L bis-MSB
Univ. Of Sheffield a-hydroxytoluene Tri-ethylphosphate 2-(4-Biphenyl)-5-phenyl-1,3,4-oxadiazole, (2-(1-Naphthyl)-5-phenyloxazole)
CHOOZ IPB Hexanol p-PTP, Bis-MSB
Eljen Technol. Anthracene Unknown 3 g/L PPO, 0.3 g/L POPOP
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Parallel Independent RD in the U.K.
Development of a gadolinium-loaded liquid
scintillator for solar neutrino detection and
neutron measurements. (Submitted to NIM
A) P.K. Lightfoot, V.A. Kudryavtsev and
N.J.C. Spooner Department of Physics and
Astronomy, University of Sheffield, Hicks
Building, Hounsfield Road, Sheffield, S3 7RH,
UK I.Liubarsky Imperial College of Science,
Technology and Medicine, London, SW7 2BW, UK R.
Luscher and N.J.T. Smith Rutherford Appleton
Laboratory, Didcot, Oxfordshire, OX11 0QX, UK
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Properties of Gadolinium-loaded
?-hydroxytoluene based scintillators.  
 
(University of Sheffield data)
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Long term stability of 10 gadolinium loaded
?-hydroxytoluene based liquid
scintillator. (University of Sheffield data)

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Comparison of the Attenuation Length(EJT and
Chooz values taken from their publications)
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Comparison of the Light Output (EJT and Chooz
values taken from their publications)
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Ongoing and Future RD at BNL

• Vary Synthesis Parameters, e.g., pH, Gd/MVA
  ratio.
• Improve Purification Procedures.
• Replace PC with Other LS Solvents, such as PCH.
• Quality Control of Long-term Stability
  Chemical, Optical, Light Output
  Temperature-dependency (rate approximately
  doubles per increase of 10o C).
• Long-Pathlength Optical Measurements.

Brookhaven Science AssociatesU.S. Department of
Energy
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UV Attenuation Change with Time (In-LS)
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Light Yield Change with Time (In-LS)
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BNL Long-Pathlength Optical system

• S2 Signal from Sample
• S3 Chopper reduces UV background ? S3 ? (S1-S2)
• S1 a reference beam for S2 ? (S1-S2)

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END
Brookhaven Science AssociatesU.S. Department of
Energy