1. 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…

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. 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

7. 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

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), 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?

9. 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

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. 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.

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.