Browsing by Subject "Neutrino"
Now showing 1 - 11 of 11
- Results Per Page
- Sort Options
Item Analytical and numerical studies of neutrino oscillations in supernovae(2012-10) Wu, Meng-RuNeutrinos are one of the central ingredients in core-collapse supernova explosion and their flavor oscillations in supernovae might affect many processes that occur in this explosive environment. In this thesis, we study neutrino flavor oscillations in supernovae both analytically and numerically. Analytically, we propose a simple model to explain the flavor evolution history in the region of collective neutrino oscillations during the neutronization neutrino burst and accretion phase of neutrino emission with low matter density. We show that the formation of spectral splits induced by collective neutrino oscillations can be well-understood using this model. We also apply this model to discuss the flavor instability of neutrino oscillations that occurs in the cooling phase. Numerically, we simulate neutrino flavor evolution history using the neutrino emission data from a state-of-the-art 18 M⊙ supernova model. We discuss the time-dependence of neutrino oscillations on neutrino emission characteristics and the supernova environment. We then study the effect of neutrino oscillations on the nucleosynthesis that occurs in the neutrino-driven wind. At last, we calculate the expected neutrino signals in the IceCube detector and discuss the consequences.Item Electron neutrino and antineutrino appearance in the MINOS detector(2013-04) Schreckenberger, Adam PaulThe Main Injector Neutrino Oscillation Search (MINOS) is a long-baseline neutrino experiment that utilizes a particle beam and two steel-scintillator calorimeters designed to determine the parameters associated with muon neutrino disappearance. Analysis methods developed by the MINOS νe group have facilitated the placement of limits upon the mixing angle associated with νμ → νe oscillations. Since the polarity of the focusing horns can be switched, we can perform a similar analysis with an antineutrino-enriched beam to select electron antineutrino appearance candidates. Using 3.34e20 POT (protons on target) in the antineutrino mode, we exclude θ13 = 0 at the 80% C.L. A joint fit of the 3.34e20 POT antineutrino and 10.6e20 POT neutrino samples excluded θ13 = 0 at the 96% C.L. In addition, the combined data were used to produce exclusions regarding the CP-violating phase.Item Energy Dependence in the Neutrino Scattering Data of MINERvA(2021-07) Mahbub, IshmamAs we prepare for lower neutrino energy beams where physics is highly energy-dependent, it is important to isolate factors that can contribute largely to these low energy neutrino experiments. The world of neutrino oscillation experiments uses a wide range of energies: from 0.7 GeV beam of T2K and MicroBooNE, 2 GeV beam of NOvA, to the 0.6 to 6.0 GeV beam produced by DUNE in the future. MINERvA’s data are currently the best place to test the upper end of the range for DUNE and can be extrapolated into both DUNE’s and NOvA’s oscillation maximum. The goal of the research is to constrain energy dependence in the neutrino scattering experiment using data from MINERvA and then determine what factors contribute to the observed energy dependence. The research is divided into two parts. First, I will analyze different theoretical models in different channels of interaction, such as the quasi-elastic and delta resonance channels, in terms of neutrino energy dependence. The goal is to study the models at the level of the structure functions, which emphasizes the W2 structure function (the C function for QE) dominates the MINERvA data, but the W3 is increasingly important for NOvA and DUNE. The second half of the research is data-driven and focuses on the different detectors and systematic effects. An experimental effect, the angle acceptance, is larger than the structure function effects. However, it is a detector geometry effect and is well measured and well modeled. Other effects such as the muon energy scale are small and localized. Additionally, the research will determine if the MINERvA GENIE model correctly predicts all of the energy dependence seen in the data, and identify the remaining unmodeled energy dependence between the MINERvA data and its best simulation.Item A measurement of neutrino oscillation parameters using anti-fiducial charged current events in MINOS.(2010-09) Strait, Matthew LevyAbstract summary: Please see PDF abstract. Some mathematical characters/symbols cannot be copied.Item Muon Neutrino Disappearance in NOvA with a Deep Convolutional Neural Network Classifier(2016-03) Rocco, DominickThe NuMI Off-axis Neutrino Appearance Experiment (NOvA) is designed to study neutrino oscillation in the NuMI (Neutrinos at the Main Injector) beam. NOvA observes neutrino oscillation using two detectors separated by a baseline of 810 km; a 14 kt Far Detector in Ash River, MN and a functionally identical 0.3 kt Near Detector at Fermilab. The experiment aims to provide new measurements of $\Delta m^2_{32}$ and $\theta_{23}$ and has potential to determine the neutrino mass hierarchy as well as observe CP violation in the neutrino sector. Essential to these analyses is the classification of neutrino interaction events in NOvA detectors. Raw detector output from NOvA is interpretable as a pair of images which provide orthogonal views of particle interactions. A recent advance in the field of computer vision is the advent of convolutional neural networks, which have delivered top results in the latest image recognition contests. This work presents an approach novel to particle physics analysis in which a convolutional neural network is used for classification of particle interactions. The approach has been demonstrated to improve the signal efficiency and purity of the event selection, and thus physics sensitivity. Early NOvA data has been analyzed (2.74$\times10^{20}$ POT, 14 kt equivalent) to provide new best-fit measurements of $\sin^2(\theta_{23}) = 0.43$ (with a statistically-degenerate compliment near 0.60) and $|\Delta m^2_{32}| = 2.48\times10^{-3}~\text{eV}^2$.Item Muon Neutrino To Electron Neutrino Oscillation in NOvA(2015-08) Sachdev, KanikaNOvA is a long-baseline neutrino oscillation experiment optimized for electron neutrino appearance in the NuMI beam, a muon neutrino source at Fermilab. It consists of two functionally identical, nearly fully-active liquid-scintillator tracking calorimeters. The near detector (ND) at Fermilab is used to study the neutrino beam spectrum and composition before oscillation, and measure background rate to the electron neutrino appearance search. The far detector, 810 km away in Northern Minnesota, observes the oscillated beam and is used to extract oscillation parameters from the data. NO?A's long baseline, combined with the ability of the NuMI beam to operate in the anti-neutrino mode, makes NO?A sensitive to the last unmeasured parameters in neutrino oscillations- mass hierarchy, CP violation and the octant of mixing angle theta23. This thesis presents the search for electron neutrino appearance in the first data collected by the NO?A detectors from October 2013 till May 2015. Studies of the NuMI neutrino data collected in the NO?A near detector are also presented, which show large discrepancies between the ND simulation and data. Muon-removed electron (MRE) events, constructed by replacing the muon in muon neutrino charged current interactions by a simulated electron, are used to correct the far detector electron neutrino appearance prediction for these discrepancies. In the analysis of the first data, a total of 6 electron neutrino candidate events are observed in the far detector on a background of 1, a 3.46 sigma excess, which is interpreted as strong evidence for electron neutrino appearance. The results are consistent with our expectation, based on constraints from other neutrino oscillation experiments. The result presented here differs from the officially published electron neutrino appearance result from the NO?A experiment where the systematic error is assumed to cover the MRE correction.Item Nuclear Effects in Neutrino Interactions at Low Momentum Transfer(2015-05) Miltenberger, EthanThis is a study to identify predicted effects of the carbon nucleus environment on neutrino - nucleus interactions with low momentum transfer. A large sample of neutrino interaction data collected by the MINERvA experiment is analyzed to show the distribution of charged hadron energy in a region with low momentum transfer. These distributions reveal a major discrepancy between the data and a popular interaction model with only the simplest Fermi gas nuclear effects. Detailed analysis of systematic uncertainties due to energy scale and resolution can account for only a little of the discrepancy. Two additional nuclear model effects, a suppression/screening effect (RPA), and the addition of a meson exchange current process (MEC), are shown to improve the description of the data.Item Quasielastic Distributions For Transverse Kinematic Variables(2019-06) Harewood, Lauren AlexandriaThe MINERvA experiment, located at the Fermi National Accelerator Laboratory (Illinois), is a detector designed to study neutrino-nuclear interactions. MINERvA has been instrumental in understanding how neutrinos interact with nuclei and its research has been used to better analyze data from oscillation experiments like MicroBooNE, DUNE (Deep Underground Neutrino Experiment) and NOvA (NuMi Off Axis v Appearance) and prepare for the future experiment DUNE. Though MINERvA has ended data collection this year, more analysis on the models of nuclear interaction happening in the nucleus is required. GENIE, a neutrino event generator, is one used to model such interactions. Upon reviewing special features in transverse kinematic distributions, the task, a flaw in a part of the model affecting nearly all interactions was found and fixed. In this study, a new GENIE simulation of a class of quasielastic neutrino events will be presented, along with results for the new transverse kinematic imbalance distributions. An approximate fix is proposed for already generated samples of simulated events.Item Studies on the module structure for the NOvA liquid scintillator neutrino detector(2014-12) Slotman, Michael JamesThis thesis contains studies pertinent to the construction of modules for the detectors of the NOvA experiment.The tensile strength of acrylic and epoxy adhesives used in construction of the detector was studied over time and with various surface preparations. Aging in oil or in air in a hot box as well as sanding and corona discharge surface treatments were examined. All materials used in the detector were studied to determine if interaction would occur with and degrade the pseudocumene liquid scintillator.Following the appearance of cracking manifold covers in installed modules, studies were done to determine the cause and mitigation of these cracks. Manifold covers that had been pressurized during a seal check during module construction were examined for the formation of cracks. Internal cracks were visible on the majority of manifold covers tested at 1.4 bar with the original containment units. It was found that reducing the pressure testing of the modules from 1.4 bar to 0.7 bar and increasing the rigidity of the pressure test containment units eliminated the formation of visible cracks in the manifold covers.Item Under The Hood: Preparing the Helium and Lead Observatory for Full Operation(2014-01) Vasel, JustinThe Helium and Lead Observatory (HALO) at SNOLAB in Canada is the world's first dedicated supernova neutrino detector. Construction of the detector is complete, but there is still work to be done before it is fully operational. In this thesis, I describe my contributions to the HALO experiment which include the testing of hardware, the design of a redundant networking scheme, and the development and implementation of a remote monitoring system.Item Using Nucleon Multiplicities to Analyze Anti-Neutrino Interactions with Nuclei(2017-07) Elkins, MirandaThe most commonly used, simple interaction models have not accurately described the nuclear effects on either neutrino-nucleus or anti-neutrino-nucleus interactions. Comparison of data collected by the MINERvA experiment and these models shows a discrepancy in the reconstructed hadronic energy distribution at momentum transfers below 0.8 GeV. Two nuclear model effects that were previously not modeled are possible culprits of this discrepancy. The first is known as random-phase-approximation and the second is the addition of a meson exchange current process, also known as two-particle two-hole due to its result in two particles leaving the nucleus with two holes left in their place. For the first time a neutron counting software algorithm has been created and used to compare the multiplicity and spatial distributions of neutrons between the simulation and data. There is localized sensitivity to the RPA and 2p2h effects and both help the simulation better describe the data. Additional systematic or model effects are present which cause the simulation to overproduce neutrons, and potential causes are discussed.