Date of Award

2000

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Physics and Astronomy

First Advisor

Robert C. Svoboda

Abstract

Data collected at the Super-Kamiokande detector have been used to make observations of the flux and spectrum of neutrinos that originate in the fusion reactions inside the center of the Sun. Previous observations of solar neutrinos have resulted in fluxes that are one third to one half the values predicted by solar models, a situation that has been labeled "the solar neutrino problem". The phenomena of neutrino oscillations is investigated as a possible solution to this problem. The Super-Kamiokande detector, located in Gifu, Japan, is a ring-imaging Cherenkov detector that detects the scattered electrons from neutrino-electron elastic scattering in the water of the detector. Recoil electrons with energies greater than 5.5 MeV are used to measure the total flux and spectrum of solar neutrinos. The observed scattering rate is found to be 15.58 +/- 0.31(stat.) events/day in the 22.5 kton fiducial volume. This is a factor of 0.458 +/- 0.009( stat.) +0.011-0.007 (sys.) of the expected rate predicted by the solar model of Bahcall and Pinsonneault, verifying the previous observations of the solar neutrino problem. Observations of the spectrum of recoil electrons and variations in the neutrino flux in different times of the day and different seasons of the year are also performed. A comparison of the neutrino fluxes measured during day and night time periods is consistent with no difference, D-N0.5D+N = -0.039(stat.) +/- 0.007(sys .). The observed spectrum and flux variations appear to be consistent with the results predicted in the absence of neutrino oscillations. These results are therefore used to generate exclusion regions in the neutrino oscillation parameter space. This dissertation describes in detail the analysis which generated these results.

ISBN

9780493069838

Pages

221

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