Publicação
Optical calibration of the SNO+experiment and sensitivity studies for the neutrinoless double beta decay
| Resumo: | SNO+ is a large volume liquid scintillator experiment for neutrino physics located 2 km underground near Sudbury, Ontario, Canada. Its main physics goal is to search for the neutrinoless double beta decay of the isotope 130Te. Neutrinoless double beta decay is a lepton number violating process that, if observed, could prove the Majorana nature of neutrinos, i.e., that they are their own antiparticles, as well as allow the measurement of their effective mass. The search for this rare process requires low backgrounds and enough precision to discriminate them. It also needs an optimized energy resolution, that is only accomplished by a full calibration of the detector. This includes an Optical Calibration, that is fundamental to characterize the propagation and collection of the optical photons created by physics events. The laserball is one of the light sources used, producing a pulsed, near-isotropic light distribution throughout the detector. Its data is used to obtain the parameters of an optical model, responsible for characterizing the response of the detector to light, through a x2 minimisation performed by the Optical Calibration Analysis software. This thesis describes the Optical Calibration of the SNO+ detector, the laserball source, the statistical fit and its validation tools. It also discusses how changes in the optical parameters affect the energy scale and resolution of the neutrinoless double beta decay spectrum and the calculation of its half-life. |
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| Autores principais: | Inácio, Ana Sofia Carpinteiro |
| Assunto: | Neutrino physics Neutrinoless double beta decay Calibration Teses de mestrado - 2017 |
| Ano: | 2017 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | SNO+ is a large volume liquid scintillator experiment for neutrino physics located 2 km underground near Sudbury, Ontario, Canada. Its main physics goal is to search for the neutrinoless double beta decay of the isotope 130Te. Neutrinoless double beta decay is a lepton number violating process that, if observed, could prove the Majorana nature of neutrinos, i.e., that they are their own antiparticles, as well as allow the measurement of their effective mass. The search for this rare process requires low backgrounds and enough precision to discriminate them. It also needs an optimized energy resolution, that is only accomplished by a full calibration of the detector. This includes an Optical Calibration, that is fundamental to characterize the propagation and collection of the optical photons created by physics events. The laserball is one of the light sources used, producing a pulsed, near-isotropic light distribution throughout the detector. Its data is used to obtain the parameters of an optical model, responsible for characterizing the response of the detector to light, through a x2 minimisation performed by the Optical Calibration Analysis software. This thesis describes the Optical Calibration of the SNO+ detector, the laserball source, the statistical fit and its validation tools. It also discusses how changes in the optical parameters affect the energy scale and resolution of the neutrinoless double beta decay spectrum and the calculation of its half-life. |
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