# Presentation: 255786

**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 

- 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% Dodecane | Beta dikitonate 
or
Carboxylate | 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-LS | Selected scintillators | TOPO, alcohol
or
carboxylate | Selected 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 Yield | H 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

- Inner-sphere complex

- Plus
- Outer-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- and 10- cm cells in ****Shimadzu UV-1601 ****spectrometer (200 – 1100 nm)**
**1-m horizontal cell, blue laser system (442 nm) **
**2-m vertical pathlength, LED variable wavelength system (350 – 700 nm, BNL Chemistry + Physics)**

**under black light**

**under room light**

## New LED for Attenuation Length

- New LED for Attenuation Length

- LED at ’s

- Beam Splitter

- CCD or PMT

**Air Vent**

**LabVIEW** DAQ

## LED Signal

## Stability of Gd-LS in PC (10 cm cells)

## Do we have another choice?

- 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 |

**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 

- 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 Yield | H atoms‡ per c.c | Flash Point |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| PC | Yes | 0.889 | 0.008/0.002 | 2 | 1.504 | 1 | 5.351022 | 48 C |
| PCH | Yes | 0.95 | 0.072/0.001 | 1.7 | 1.526 | 0.46 | 3.721022 | 99 C |
| DIN | Yes | 0.96 | 0.040/0.023 | >10 |  | 0.87 | 5.451022 | >140 C |
| PXE | Yes, but not stable | 0.985 | 0.044/0.022 | 2.1 |  | 0.87 | 4.341022 | 167 C |
| LAB | Yes | 0.86 | 0.001/0.000 | 1 | 1.482 | 0.98 | 6.311022 | 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 | ~ | 4.771022 | 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?
- 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%).
- 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.