Update of US Gd-LS

1. Update of US Gd-LS Minfang Yeh and Richard L. Hahn BNL, Chemistry Department, Upton NY

2. 430 nm Optical of ~1% Gd in LAB and in PC • Few percents of Gd can be loaded into pure LAB or pure PC, respectively, using BNL carboxylate recipe. • Both LS needs additional organic solvent: • Gd-LAB needs diluent (PC) to dissolve certain shifters. • Gd-PC needs inert diluent (MO or dodecane) to improve compatibility.

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

4. BNL Proposed Gd-LS (1) 12 L of 0.2%Gd in 20%PC + 80%dodecane situated at the University of Chicago for prototype

5. Light Yield as a Function of PC% in dodecane

6. BNL Proposed Gd-LS (2) Light yield is ~100% of PC

7. Buffer/Shielding

8. Buoyant Force http://www.ac.wwu.edu/~vawter/PhysicsNet/QTMovies/PressureFluids/

9. Selection of Fluors

10. Example of PBD vs butyl-PBD Q1: Adding bis-MSB in butyl-PBD doesn’t improve the light yield much; on the other hand, additional bis-MSB in PBD increases the light yield by a factor of ~2. Q2: What are the quantities of shifters that we need?

11. Light Yield as a Function of Fluors (butyl-PBD:bis-MSB=200:1)

12. Blending of Conc. Gd-LS • Immiscibility of solvents. • Localization of Gd compound can cause irreversible precipitation • Controlled Mixing: • Fast and vigorous (not suitable for massive quantity) • Slow and gentle, i.e., Gd-PC/MO at ~3L/min (Palo Verde at 200 L per batch) • Commercially available 100-L (capable of upgrade to 300-L) Jacketed System with air or electric pump

13. Port of Houston Transportation and Storage of LS • 20ft by 8ft ISO tank, the shipping container conforming to the standards set by International Standards Organization, can be leased at ~few $thousands per year. • The tank shell is made of stainless steel and holds 6,341 gallons of liquid. photos adapted from NOvA

14. Gd/H and C/H Ratios • Cold/Thermal Neutron Analysis • Institute of Isotopes, Dept. of Nuclear Research • Hungary Academy of Science, Budapest, Hungary • Samples sent out on May 20, 2006 • 0.1% Gd in 90% LAB and 10% PC • 0.1% Gd in 80% dodecane and 20% PC • 80% dodecane and 20% PC • 100% LAB • Samples received on June 04, 2006; will be analyzed next week. • Nuclear Magnetic Resonance • Brookhaven National Laboratory, Chemistry Dept. • A FaST team (Dr. S. Seleem and her students) will work with us at BNL beginning on June 26.

15. Summary and Future Work • Samples of 0.1~0.2% of Gd in a variety of liquid scintillators and their mixtures are continuously monitoring : • 546 days for 0.2%Gd in 100%PC • 416 days for 0.2%Gd in 20%PC-80%dodecane • 456 days for 0.2%Gd in 40%PC-60%dodecane • 189 days for 0.2% Gd in 100%LAB • 189 days for 0.2% Gd in 20%PC - 80%LAB • The productivity of Gd-LS at 1-L of 1%Gd-LS (~ 10L of 0.1%Gd-LS) per preparation is consistent; exploring the techniques and equipments for even larger quantity (10L of 1% Gd-LS) production. • Fluorescence for fluors in different combinations of liquid scintillators need to be studied further. • People • Compatibility test of acrylic vs. organic solvent. • Chemical assays to remove and to measure U/Th. • Prototype in Aberdeen Tunnel HK