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.