BNL Gd-LS for theta-13

1. 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

2. History of Gd- loaded1 and unloaded2 LS

3. 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?

4. Fill in the blanks?

5. BNL M-LS Synthesis Systems

6. M-LS Characterization is important to optimize the synthesis Inner-sphere complex 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 Plus Outer-sphere ligands: [H2O], [OH-], [NH4+] and [Cl-]

7. 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.

8. 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 room light under black light

9. Fiber Collimator 2.5 m 2.0 m Splitter Cube Beam Splitter LED at ’s New LED for Attenuation Length Air Vent LabVIEW DAQ CCD or PMT

10. LED Signal

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

12. 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. PC has drawbacks of low flash point and chemical aggressiveness. Do we have another choice?

13. 1 1 0 LAB from SNO+/++ linear alkyl chains of 10-13 C atoms with a benzene ring; used primarily for the production of biodegradable synthetic detergent high light yield, high flash point, low toxicity, cheap  an ideal scintillator for neutrino experiment

14. Optical of LAB after Staged Purification

15. Optical of ~1% Gd in LAB and in PC 430 nm • 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

16. Stability of Gd-LS in LAB (10 cm cells)

17. The blanks were filled after X years…

18. 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.