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) Gd in LSGd-Carboxylate Liquid Scintillator PC + dodecane Loading Methods Solvent-solvent Extraction [Gd]1 g/L Density~0.79 g/mL > 15m Stability> 1.5 years Future Study Mature and ready for prototype study; Compatibility Test 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) Gd in LSGd-Carboxylate Liquid Scintillator PC + LAB Loading Methods Solvent-Solvent Extraction [Gd]1 g/L Density~0.87 g/mL > 15m Stability> 6 months Future Study Compatibility Test QC monitoring Light yield is ~100% of PC

7 Buffer/Shielding Mineral Oil (C 24 ~C 28 ) LAB (C 11 ~C 13 ) Water Cost   Flash Point215 o C130 o C- PurityNot consistent Controlled production Easy to purify Availability   Density0.85 g/mL0.86 g/mL1 g/mL

8 Buoyant Force

9 Selection of Fluors Wavelength Shifter (shift the UV light to the visible region) PrimarySecondary Concentration (1.5 ~ 6 g/L) t d (ns) Concentration (15 ~300 mg/L) t d (ns) butyl-PBD 1.1 bis-MSB1.6 PPO1.5 p-TP0.95 POPOP1.5 PBD1.1

10 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? Example of PBD vs butyl-PBD

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 photos adapted from NOvA  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. Transportation and Storage of LS

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, % Gd in 90% LAB and 10% PC 2.0.1% Gd in 80% dodecane and 20% PC 3.80% dodecane and 20% PC 4.100% 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