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

How It Works - SNO D2OD2O D 2 O + WLS 2 Acrylic Cutoff < 330 nm

SNOOPTICS

O O CH 2 CO CH 3 N O H2NH2N HO 3 S O O O O CH 2 COH CH 3 O HO O N CH 3 H2NH2N H O O COH CH 3 O HO O O CH 3 HO carbostyril 124 Alexa Fluor 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

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 MnO x, 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 wavelength shifters – Alexa Fluor 350, 4-methyl umbelliferone Attenuation lengths Winn-Raftery water-based scintillator

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.