Use of Wavelength Shifter to Enhance Cerenkov Light Detection Art McDonald

1. Use of Wavelength Shifter to Enhance Cerenkov Light Detection Art McDonald SNO Institute, Queen’s University Kingston, Ontario, Canada

2. D2O D2O + WLS How It Works - SNO Acrylic Cutoff < 330 nm 2

3. SNO OPTICS

4. H2N O O O HO3S CH2 C O N CH3 O O HO O O CH2 C OH CH3 O carbostyril 124 Alexa Fluor 350 H H2N O N CH3 7-hydroxy-4-methylcoumarin 7-hydroxy-4-methylcoumarin-3-acetic acid HO O O C OH CH3 O 7-hydroxycoumarin-3-carboxylic acid HO O O CH3 Wavelength Shifters Tested Found to Require ph > 9, discarded

6. WLS candidates Xin Dai Xin Dai 6

7. 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.

8. Cerenkov Info still exists

9. COST $ 7.2 Million for 1 ppm In 10 Megaton module

10. Tests at TRIUMF for JPARK to SK Near Detector Mostly Electrons

11. X 2.2 at 10 ppm x 1.8 at 1 ppm

12. Future Measurements at TRIUMF • Other wavelength shifters – Alexa Fluor 350, 4-methyl umbelliferone • Attenuation lengths • Winn-Raftery water-based scintillator

13. 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.