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.