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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Tests of neutrino interaction models with the MicroBooNE detector

Rafique, Aleena January 1900 (has links)
Doctor of Philosophy / Department of Physics / Timothy A. Bolton / I measure a large set of observables in inclusive charged current muon neutrino scattering on argon with the MicroBooNE liquid argon time projection chamber operating at Fermilab. I evaluate three neutrino interaction models based on the widely used GENIE event generator using these observables. The measurement uses a data set consisting of neutrino interactions with a final state muon candidate fully contained within the MicroBooNE detector. These data were collected in 2016 with the Fermilab Booster Neutrino Beam, which has an average neutrino energy of 800 MeV, using an exposure corresponding to 5e19 protons-on-target. The analysis employs fully automatic event selection and charged particle track reconstruction and uses a data-driven technique to separate neutrino interactions from cosmic ray background events. I find that GENIE models consistently describe the shapes of a large number of kinematic distributions for fixed observed multiplicity, but I show an indication that the observed multiplicity fractions deviate from GENIE expectations.
2

FEW-ELECTRON SIGNALS IN LIQUID XENON DARK MATTER DETECTORS

Abigail Kopec (11519857) 22 November 2021 (has links)
An overwhelming majority of matter in the Universe is dark matter, a substance unlike anything we know. Detecting dark matter particles requires ruling out observed phenomena caused by known particles. This thesis advances efforts toward the detection of dark matter using one of the most sensitive particle detection technologies: the dual-phase liquid xenon time projection chamber. Specifically, data from the XENON1T Experiment, located in Italy, and the Purdue small-scale ASTERiX detector are analyzed. A background of Lead-214 beta decay events can be mitigated by tracing the radioactive Radon-222 decay chain in XENON1T. However, a preliminary reduction of background has a high cost to exposure. Research on several topics was conducted with Purdue undergraduates, including a search for dark matter particles up to the Planck Mass, characterizing backgrounds due to muons, and searching for Boron-8 solar neutrino signals. XENON1T single-scatter dark matter limits were extended to a particle mass of 10<sup>18 </sup>GeV/c<sup>2</sup>. The ASTERiX detector was modified to characterize a significant background to the smallest detectable energy signatures: single- and few-electron ionization signals. Infrared light was determined to be ineffective at reducing this background, and their rates were observed to decrease inversely with time since an energetic interaction according to a power law. The rates of single- and few- electron backgrounds increase linearly with increased applied extraction fields and increased depth of the initial interaction in the detector. These results indicate that these backgrounds originate at the liquid-gas interface of dual-phase detectors. In exploring a single-photon threshold for initial scintillation signals, a previously unconsidered background of large dark count signals in the photosensors became apparent. The high background of small ionization signals and large dark count signals deterred a search for Boron-8 solar neutrino interactions in XENON1T. These studies are vital to mitigating backgrounds and improving the sensitivity of liquid xenon time projection chambers to new physical phenomena.
3

[pt] SENSIBILIDADE DA PRÓXIMA GERAÇÃO DE DETECTORES DE NEUTRINO À OBSERVAÇÃO DOS EFEITOS DA MATÉRIA DA TERRA EM NEUTRINOS QUE VEM DE SUPERNOVAS NO CONTEXTO DO DECAIMIENTO INVISÍVEL DE NEUTRINOS / [en] SENSITIVITY OF NEXT-GENERATION NEUTRINO DETECTORS TO THE OBSERVATION OF EARTH MATTER EFFECTS ON SUPERNOVA NEUTRINOS IN THE FRAMEWORK OF INVISIBLE NEUTRINO DECAY

EDWIN ALEXANDER DELGADO INSUASTY 25 January 2022 (has links)
[pt] Nesta tese estudamos o potencial que terão a próxima geração de detectores de neutrinos (JUNO, Hyper-Kamiokande e DUNE) para a detecção dos efeitos da matéria da Terra através da identificação das modulações no espectro de energia dos neutrinos de supernovas de colapso de núcleo em nossa galáxia, assumindo a possibilidade do decaimiento invisível de v2 após os neutrinos terem deixado a estrela, caminho da Terra. Simulações recentes do colapso gravitacional (e subsequente explosão) de estrelas com massa maior do que ~ 8Mo mostram que durante a fase de esfriamento as energias médias (Eve) e (Evx) tornam-se muito semelhantes e os fluxos tendem a se igualar, tornando difícil observar os efeitos da matéria da Terra usando um único detector. Neste trabalho mostramos que a inclusão do decaimiento dos neutrinos também cria a possibilidade de observar os efeitos em consideração no canal de detecção de neutrinos se o ordenamento de massa for normal e no canal anti-neutrino se o ordenamento for invertido, o que não é esperado na ausência de decaimento. Em particular, se a taxa de decaimento for maior do que ~ 70%, descobrimos que o decaimento invisível de v2 pode aumentar as possibilidades de observação dos efeitos da matéria da Terra, mesmo para supernovas a uma distância de 10 kpc de nós. / [en] In this thesis we studied the potential that the next-generation neutrino detectors (JUNO, Hyper-Kamiokande and DUNE) will have to the detection of the Earth matter effects through the identification of the modulations in the energy spectrum of neutrinos from core-collapse supernovae in our galaxy, assuming the possibility of the invisible decay of v2 after the neutrinos have left the star, on their way to Earth. Recent simulations of gravitational collapse (and subsequent explosion) of stars more massive than ~ 8Mo show that during the cooling phase the average energies (EVe) and (Evx) become very similar and the fluxes tend to equalize, making it difficult to observe the Earth matter effects using a single detector. In this work we show that the inclusion of neutrino decay creates also the possibility of observing the effects under consideration in the neutrino detection channel if the mass ordering is normal and in the anti-neutrino channel if the ordering is inverted, which is not expected in the absence of neutrino decay. In particular, if the decay rate is more than ~ 70%, we find that the invisible neutrino decay of v2 can enhance the observation possibilities of Earth matter effects even for supernovae at a distance of 10 kpc from us.

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