Updates of BNL Gd-LS

1. Updates of BNL Gd-LS Nuclear Chemistry/Solar Neutrino Group Richard L. Hahn, Minfang Yeh, Alex Garnov Claude Musikas Students…

2. Gd(MVA)3 Carboxylates A organo-Gd carboxylate, Gd(MVA)3, can be loaded into organic solvent depending on the compatibility of this complex with the scintillator of interest  Polarity, Solubility and Miscibility. BNL has developed a series of chemical methods that can be used to prepare Gd-LS in large-scale production (~tons) for theta-13 reactor neutrino experiments.

3. 0.2% Gd in 20%PC-80%Dodecane

4. Gd-LS Attenuation Stability

5. Attenuation Length from UV-Vis • L is attenuation length • L is path length = 10 cm for UV-Vis and >> 1m for laser • A(L) is absolute absorption at 430 nm • L = (0.434 * 10 cm)/(0.008) = 542 cm = 5.4 m M. Yeh

6. Lock-in Amplifier Photo- Detector S2 S1 Spherical Mirror 10-cm Herriott cell Spherical Mirror S3 Photo- Detector 1-meter glass Herriott cell Mirrors Beam Chopper HV Power Supply 50 mW, Blue LASER, 442 nm Density Filter O.D.=1 Dual-beam Long-path Optic System • S2 – Signal from Sample • S3 – Chopper reduces UV background  S3  (S1-S2) • S1 – Reference beam for S2  (S1-S2) M. Yeh

7. Fiber Collimator 2.5 m 2.0 m Splitter Cube Beam Splitter LED at ’s Vertical LED System Air Vent Solvent Inlet DAQ CCD or PMT

8. Goals of Vertical LED System • Measure optical transmission in fluids, for different pathlengths and different wavelengths. • Do the data follow a single exponential? • Test Beer-Lambert Law: • Transmission = I/I(0) = 10(-Abs) = 10(-LC), withL=pathlength, C=concentration,=molar absorptivity. Depends on wavelength. • See Raleigh scattering vs. wavelength? • See Refraction at boundaries? • Would results be relevant to RAT simulations?

9. Beer’s law applicable to different LED ’s. LED Detection Stability beam A from LED beam B after solvent

10. Is light yield of Gd-LS a function of temperature (± 10oC)? Temperature-controlled (-40oC to +130oC) Chamber >95% UV-transmitting light guide Gd-LS 137Cs PMT

11. Motor Air vent N2 inlet diluent conc. Gd-LS Are we ready for the prototype? Large Scale Production • Capable of producing ~few hundreds mL of conc. Gd-LS per week. • A 5-L air-free, glass mixing tank with Teflon propeller. • 200-L 0.1% Gd-LS can be done in few months.

12. Conclusions re Gd-LS • Our development of Gd-loaded scintillator is mature. • Samples of 0.2% Gd in mix’s of PC and dodecane are stable for hundreds of days (200 days for 20%-80%, 260 days 40%-60%, and 340 days for 100%). • Capable of producing hundreds of liters of 0.1% Gd-LS for prototype in few months. • Another dilutant (LAB – Linear Alkyl Benzene) to enhance the light yield of final 0.1% Gd-LS? • Compatibility tests of SNO acrylic vs. organic solvents.

13. P.S. - New BNL Developments • BNL Chemistry Dep’t. – Granting of LDRD (Lab Director R&D) funding for FY-06 (and future?) to hire 1-2 postdocs for Gd-LS R&D. = “Seed Corn”. • BNL Physics Dep’t. – (a) I have been advertising the topic of reactor theta-13 for several months. (b) Several HE physicists have expressed serious interest in joining a reactor theta-13 experiment. (c) Ed Blucher will visit BNL in mid-November to proselytize for Braidwood and give a Physics Dep’t. Seminar. (d) BNL is preparing a long-term proposal for neutrino R&D to send to OHEP, for (i) accelerator-based and for (ii) for new detector developments.