Use of Wavelength Shifter to Enhance Cerenkov Light DetectionUse of Wavelength Shifter to Enhance Cerenkov Light Detection
Art McDonaldArt McDonaldSNO Institute, Queen’s UniversitySNO Institute, Queen’s University
Kingston, Ontario, CanadaKingston, Ontario, Canada
How It Works - SNO
D2O D2O
+ WLS
2
Acrylic Cutoff< 330 nm
SNOSNOOPTICSOPTICS
OO
CH
2
C OCH3
N
O
H2N
HO3S
O
O
OO
CH
2
C OHCH3 O
HO
ON
CH3
H2N
H
OO
C OHCH3 O
HO
OO
CH3
HO
carbostyril 124
Alexa Fluor 350
7-hydroxy-4-methylcoumarin
7-hydroxy-4-methylcoumarin-3-acetic acid
7-hydroxycoumarin-3-carboxylic acid
Wavelength Shifters TestedWavelength Shifters Tested
Found toRequireph > 9,discarded
200 300 400 500 6000
100
200
300
400
500
600
700
800
900
10001.0 ppm carbostyril 124July 10, 2003
pH: 5.0 Excitation, em=417 nm Emission, ex=340 nm
pH 7.0: Excitation, em=417 nm Emission, ex=340 nm
pH 9.0: Excitation, em=417 nm Emission, ex=340 nm
Inte
nsit
y (a
.u.)
Wavelength (nm)
WLS candidates
6
Alexa Fluor 350 Carbostyril 124pH dependence No NoQuantum efficiency 92% 96.00%Emission peak 442 nm 417 nm
200 300 400 500 600
0
100
200
300
400
500
1.0 ppm Alexa Fluor 350July 10, 2003
pH: 5.0 Excitation, em=443 nm Emission,
ex=340 nm
pH 7.0: Excitation,
em=443 nm
Emission, ex=340 nmpH 9.0:
Excitation, em=443 nm Emission,
ex=340 nm
Inte
nsit
y (a
.u.)
Wavelength (nm)
200 300 400 500 6000
100
200
300
400
500
600
700
800
900
10001.0 ppm carbostyril 124July 10, 2003
pH: 5.0 Excitation, em=417 nm Emission, ex=340 nm
pH 7.0: Excitation, em=417 nm Emission, ex=340 nm
pH 9.0: Excitation, em=417 nm Emission, ex=340 nm
Inte
nsit
y (a
.u.)
Wavelength (nm)
Xin Dai Xin Dai
Further testsFurther tests
Long Term Stability: < 5% change in emission over 6 months testing for Carbostyril and Alexa Fluor
Increased output: Calculated factor of > 2 increase in detectable Cerenkov light for Carbostyril.
Timing: Fluorescence Lifetime of 5.6 ns for Alexa Fluor and 6.2 ns for Carbostryil.
Calculated attenuation length: Greater than 40 meters for wavelengths > ~ 400 nm
Other effects: No interaction with acrylic or MnOx, Hydrous Titanium Oxide used for Radium measurements and purification.
Removable with activated charcoal.
Cerenkov Info still exists
COST
$ 7.2 Million for 1 ppmIn 10 Megaton module
Tests at TRIUMF for JPARK to SK Near DetectorTests at TRIUMF for JPARK to SK Near Detector
MostlyElectrons
x 1.8 at 1 ppm
X 2.2 at 10 ppm
Future Measurements at TRIUMF
• Other wavelength shifters – Alexa Fluor 350, 4-methyl umbelliferone
• Attenuation lengths
• Winn-Raftery water-based scintillator
Other Ideas for the future …Other Ideas for the future …
Tailored Nanocrystals for wavelength shifting or water-based scintillation???
At < 5 nm size and < 1% loading, Rayleigh scattering could be manageable.