1. BNL Neutrino/Nuclear Chemistry Group
Updates of BNL Gd-LS
BNL Neutrino/Nuclear Chemistry Group
Richard Hahn Leader, Senior Scientist
Minfang Yeh Associate Scientist
Alex Garnov Post Doc
(Group reduced to 3 people. Alex will depart April 5, Starting search for his replacement.)

2. Attenuation Length Measurements
1- and 10- cm cells in Shimadzu UV-1601 spectrometer (200 – 1100 nm)
1-m horizontal cell, blue laser system (442 nm)
1.5-m vertical pathlength, LED variable wavelength system (350 – 700 nm, working with M. Diwan of BNL Physics)
under room light
under black light

3. Gd-LS Attenuation Stability (10 cm cells)
You should probably comment that the Braidwood collaboration had decided to use 0.2% Gd, to increase the signal and shorten the capture time to ~15 microsec.
(1) Someone may ask why the absorbance depends (a) on the Gd concentration, and (b) on the ratio of PC to dodecane.
(2) You should remind them how the Abs. Value is related to the Attenuation Length; e.g.,  10 meters.
Abs = ~ Atten. Length = 10 m

4. Scintillator Selection
Gd Loading
d (g/cm3)
UV Abs.430 before/after
Purif. Method
n20
Light Yield
H atoms‡ per c.c
Flash Point PC
Yes
0.889
0.008/0.002
Vacuum Distil.
1.504 1
5.351022
48 C
PCH
0.95
0.072/0.001
Column
1.526
0.46
4.281022
99 C
DIN
0.96
0.040/0.023
0.87
3.271022
>140 C
PXE
Yes, but not stable
0.985
0.044/0.022
3.381022
167 C
LAB
0.86
0.001/0.000
1.482
0.98
2.521022
130 C
Mineral Oil No
0.85
0.002 ~0.001
N/A
~1.46 ~
1.62 –1.65 1022
215 C
Dodecane
No (<20%)
0.75
0.001 ~0.000
1.422
3.181022
71 C
Explain “be/af”. Are these the Abs values before and after the purification?
‡calculated from density.

5. New Candidate for 13 Experiment
LAB (Linear Alkyl Benzene) containing side alkyl chains of C atoms; average ~11.3 atoms.
Long attenuation length, low cost, low reactivity, high flash point, and high light yield  An ideal scintillator, discovered from our collaborative SNO+/++, that can also be used in 13 experiment.
Boiling Point (oC)
Melting Point (oC)
< -50
Flash Point (oC)
130
Vapor Pressure (mmHg)
< oC
Vapor Density (Air =1)
8.1
Solubility in Water
Insoluble
Molecular Weight
233 – 237 g/mol pH
Not applicable
Viscosity
5 – 10 20oC
Evaporation Rate (water =1)

6. LAB Purification

7. Light Yield of LAB versus PC
3 g/L PBD + 15 mg/L bis-MSB

8. Optical Spectrum of 0.2% Gd in 20%PC-80%LAB
Fact: 20%PC-80% LAB mixture is stable for ~ 1.5 month since synthesis.
Question: Can we load Gd directly into LAB? Answer: Yes!

9. Optical Comparisons of ~1% Gd in LAB and PC
430 nm
BNL has successfully loaded Gd into 100% LAB
Gd-LAB has much better transparency at < 400 nm and at least ~50% improved optical transparency at 430 nm, compared to Gd-PC

10. ~1% Gd in LAB and PC
430 nm
Gd-LAB has much better transparency at < 400 nm and ~20% better optical at 430 nm, compared to Gd-PC

11. h Funding Constraints of the BNL Group: Personnel costs
This EOI was requested by OHEP.
My group’s base program comes from DOE/ONP.
We took a major hit in FY-06. Currently are barely able to support our existing 3-person group.
It is not at all clear if ONP will give any support for reactor theta-13 work.
We are starting to write our new FWP, due in early February for FY
I plan to talk with ONP (Gene Henry) in the next week; also with OHEP to get their input about this issue.
Brookhaven Science Associates U.S. Department of Energy h

12. h Funding Constraints of the BNL Group: Personnel costs, II
We are involved in other neutrino R&D, re solar
neutrinos and double beta-decay. Our major thrust is
on Metal-loaded LS, with current main emphasis on
Gd-LS for theta-13.
Other efforts: (a) Compatibility of M-LS with acrylic
and other structural materials. (b) Radioactive
contaminants, assay and control.
Basic Questions: Will ONP continue to fund our “base
program” with supplementary support for theta-13 from
OHEP? Or, will ONP share theta-13 costs with OHEP?
Or Horrors! Will ONP cut us significantly?
Brookhaven Science Associates U.S. Department of Energy h

13. h Funding Constraints of the BNL Group: Personnel costs, III
In summary, there is a likely chance that we will not
receive ONP funding for postdocs to work on Theta-13.
What to do? Should we ask OHEP for this support?
Basic annual total cost of a postdoc at BNL is
$100 K (includes all overhead costs).
Our bare minimum need is one new postdoc;
two are preferable.
Brookhaven Science Associates U.S. Department of Energy h

14. h Funding Constraints of the BNL Group: “Materials”costs, I
Let’s not lose sight of the fact that the Gd-LS tests
that we have been doing at BNL involve small
Amounts, <1 L batches.
Clearly we want to scale this up to several L, or even
more. I am not comfortable basing all of our claims
about the quality of the Gd-LS on small samples,
especially since our full-scale detector modules will
contain 65 tons each. Might we be fooling ourselves?
Costs for chemicals, materials, and equipment
specifically for Gd-LS: Our request in our 2004
proposal was very modest, $28 K.
Brookhaven Science Associates U.S. Department of Energy h

15. h Funding Constraints of the BNL Group: “Materials”costs, II
Is that sufficient for our R&D? We are building new
Systems at BNL, e.g., to scale up our Gd-LS production
to tens of liters per batch, to measure optical
transparency of large volumes,…
A major question is: do Braidwood people want
appreciable amounts of Gd-LS, to do tests independent
of the BNL Group, to get data to validate Monte Carlos,…
So far, the only request I have is from Ed, for ~10 L
for his small-scale prototype at Chicago.
Is that all? The cost to a large extent depends on
your needs. What shall we do?
Brookhaven Science Associates U.S. Department of Energy h