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

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.

0.2% Gd in 20%PC-80%Dodecane

Gd-LS Attenuation Stability

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

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

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

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), with L=pathlength, C=concentration, =molar absorptivity. Depends on wavelength. See Raleigh scattering vs. wavelength? See Refraction at boundaries? Would results be relevant to RAT simulations?

LED Detection Stability Beer’s law applicable to different LED ’s. beam A from LED Question: Beam A = I(0), Beam B = I after the liquid. So we would expect that Area (B) divided by Area (A) = I(0)/I should be less than 1. In the Figure, B looks bigger than A. Why? beam B after solvent

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

Are we ready for the prototype? Large Scale Production diluent conc. Gd-LS Motor Air vent N2 inlet 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.

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.

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.