Use of Wavelength Shifter to Enhance Cerenkov Light Detection
Art McDonald
SNO Institute, Queen’s University
Kingston, Ontario, Canada
How It Works - SNO
D2O
D2O
+ WLS
2
Acrylic Cutoff
< 330 nm
SNO
OPTICS
O
O
CH2
C
O
CH3
N
O
H2N
HO3S
O
O
O
O
CH2
C
OH
CH3
O
HO
O
N
CH3
H2N
H
O
O
C
OH
CH3
O
HO
O
O
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 Tested
Found to
Require
ph > 9,
discarded
WLS candidates
6
Xin Dai
Xin Dai
Further 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 ppm
In 10 Megaton module
Tests at TRIUMF for JPARK to SK Near Detector
Mostly
Electrons
x 1.8 at 1 ppm
X 2.2 at 10 ppm
Future Measurements at TRIUMF
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.