Item – Theses Canada

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OCLC number
1006696370
Link(s) to full text
LAC copy
LAC copy
Author
Moffat, Bryce,1972-
Title
The optical calibration of the Sudbury Neutrino Observatory
Degree
Ph. D. -- Queen's University, 2001
Publisher
Ottawa : National Library of Canada = Bibliothèque nationale du Canada, [2002]
Description
3 microfiches
Notes
Includes bibliographical references.
Abstract
SNO is designed to detect Cherenkov light emitted in low-energy interactions over the range 0-20 MeV. The primary signals being studied by the Observatory are interactions of 8B solar neutrinos with D2O. The optical calibration of the Sudbury Neutrino Observatory (SNO) is a vital pre-requisite to the precision of the analysis of solar neutrino data from the detector. The optical calibration uses a light diffusing sphere and a pulsed nitrogen/dye laser with five selectable dyes to sample the detector optical properties as a function of wavelength and position. The principal detector optical parameters determined are the D2O and H2O attenuations, and the angular response of the photomultipliers. The attenuation of light in the ultra-pure D2O is measured at six wavelengths between 337 nm and 620 nm to be between (4.44 ± 1.33) * 10-5 cm-1 at 620 nm and (10.17 ± 1.45) * 10-5 cm-1 at 372 nm. These results are a factor of ~1/3 lower than previous measurements of Boivin et al. [1]. At this low level, the attenuation plays a greatly reduced role in determining the energy response of SNO to neutrino interactions. The 'in situ' measurement of the photomultiplier (PMT) angular response is well determined over the range 0-40° by the optical data. The PMT response is 5 to 10% higher than the calculations and ' ex situ' measurements of Lay [2] and Lyon [3] over the range of incident angles (25~40°) most relevant to the neutrino measurement in the D2O fiducial volume. The uncertainty in the PMT angular response increases with incident angle up to approximately 1% at the largest angles sampled. Monte Carlo simulations and analytic calculations of the detector response to electrons and gamma-rays rely on the measured optical parameters. Both methods provide a way to interpolate between and to extrapolate beyond the radioactive source measurements taken at specific locations in the detector. Gamma rays from 16N are used to verify the energy response calculations and agreement is to <math> <f> </f> </math>1% at the sampled positions within the 550 cm heavy water fiducial volume. The effects of systematic variations in the inputs to the detector optics measurement have only a small effect (<math> <f> </f> </math>0.13%) on the overall detector response to Cherenkov interactions. However, uncertainties in the extrapolation of the photomultiplier angular response beyond the measured range increase this uncertainty to ~1.25%.
ISBN
0612634396
9780612634398