Repository logo

Browsing by Author "Buchanan, Norm, committee member"

Now showing 1 - 6 of 6
  • Thumbnail Image
    ItemOpen Access
    Design of a compact integrated high-power superconducting radio frequency electron beam source and klystron-inspired terahertz power source
    (Colorado State University. Libraries, 2018) Sipahi, Nihan, author; Maciejewski, Anthony A., advisor; Collins, George J., committee member; Chong, Edwin K. P., committee member; Buchanan, Norm, committee member
    There exists a need for compact, reliable, high-power electron sources for applications including those in industry, basic science, medical science and security. There also exists a need for compact electron-beam based light and power sources of various power levels and at different frequencies (mm-wave to gamma rays) for applications also in the fields of basic science, industry, and security. Today's examples of high-average-power electron sources are neither very compact nor highly efficient. The same may be said for many of the electron-beam based light sources operated worldwide for a myriad of applications. Recent breakthroughs in superconducting (SC) materials technology, radio-frequency (RF) power systems, specialized cathodes, and RF cavity designs offer ways to overcome the above-mentioned shortcomings. In this dissertation, all of these new features are integrated in a comprehensive design into one promising concept for a compact superconducting RF (SRF) high-average power electron linear accelerator. This integrated design is capable of 5-50 kW average electron beam power and continuous-wave operation with the corresponding electron beam energy up to 10 MeV. In addition, the community also has a need for compact sources for many different wavelength regimes, as well as a variety of peak and average powers. Specifically, we are also exploring a novel continuous wave terahertz source designed from using basic principles of the beam manipulation methods used in free-electron laser (FEL) light sources.
  • Thumbnail Image
    ItemOpen Access
    Determining synchronization of certain classes of primitive groups of affine type
    (Colorado State University. Libraries, 2022) Story, Dustin, author; Hulpke, Alexander, advisor; Adams, Henry, committee member; Buchanan, Norm, committee member; Gillespie, Maria, committee member
    The class of permutation groups includes 2-homogeneous groups, synchronizing groups, and primitive groups. Moreover, 2-homogeneous implies synchronizing, and synchronizing in turn implies primitivity. A complete classification of synchronizing groups remains an open problem. Our search takes place amongst the primitive groups, looking for examples of synchronizing and non-synchronizing. Using a case distinction from Aschbacher classes, our main results are constructive proofs showing that three classes of primitive affine groups are nonsynchronizing.
  • Thumbnail Image
    ItemOpen Access
    Late residual neural networks: an approach to combat the dead ReLU problem
    (Colorado State University. Libraries, 2022) Ernst, Matthew Frederick, author; Whitley, Darrell, advisor; Anderson, Chuck, committee member; Buchanan, Norm, committee member
    The rectified linear unit (ReLU) activation function has been a staple tool in deep learning to increase the performance of deep neural network architectures. However, the ReLU activation function has trade-offs with its performance, specifically the dead ReLU problem caused by vanishing gradients. In this thesis, we introduce "late residual connections" a type of residual neural network with connections from each hidden layer connected directly to the output layer of a network. These residual connections improve convergence for neural networks by allowing more gradient flow to the hidden layers of a network.
  • Thumbnail Image
    ItemOpen Access
    Massive neutrinos and the see saw mechanism
    (Colorado State University. Libraries, 2014) Campbell, Thomas, author; Toki, Walter, advisor; Buchanan, Norm, committee member; Biedron, Sandra, committee member
    In the current standard model of particle physics, neutrinos are massless and strictly left-chiral. With neutrino oscillations definitively observed, we know experimentally that neutrinos have non-zero mass. The standard model for leptons, including the Higgs mechanism for mass generation will be explored. Extensions to the standard model to give neutrinos mass and the so called see-saw mechanism will then be presented. Finally, one model of the see-saw mechanism purposed by S. F. King will then be compared to recent data from the T2K experiment.
  • Thumbnail Image
    ItemOpen Access
    Measurement of the muon anti-neutrino charged current double differential cross section with no pions in the final state on water using the pi-zero detector at T2K
    (Colorado State University. Libraries, 2018) Campbell, Thomas, author; Toki, Walter, advisor; Biedron, Sandra, committee member; Buchanan, Norm, committee member; Wilson, Robert J., committee member
    The T2K (Tokai to Kamioka) experiment is a long baseline neutrino oscillation experiment where a narrow band (by energy) neutrino beam of primarily muon neutrinos or muon anti-neutrinos is produced in Tokai and directed towards Kamioka in Japan. Neutrinos in the beam are first detected at the T2K near detector complex 280 m from the beam source (ND280) and then travel 295 km before being detected again at the Super-Kamiokande (Super-K) water-Cherenkov detector. In addition to measuring the flux of neutrinos in the T2K beamline en route to Super-K, other physics analyses are performed at ND280. This thesis describes one such measurement where the π0-detector (P∅D) and a time projection chamber at ND280 were used to measure the charged-current cross section for muon anti neutrinos with water as the interaction target and no pions in the final state. Such a cross section is a T2K and world first. This cross section was measured differentially by the outgoing lepton true kinematics using a binned likelihood fitting framework recently developed at T2K. The thesis will provide: an introduction to neutrinos in the context of a cross section measurement, a description of the T2K experiment including common software tools used in analysis, a general discussion of concerns in differential cross section measurements, a mathematical formulation of the likelihood fitting procedure, details of the neutrino event selection process, the chosen parameterization and validation of the fit, and finally, the cross section results in data with a discussion of the significance and conclusions of the measurement. The total cross section integrated over all differential bins considered in the analysis is measured to be: σ = (7.844 ± 1.316) × 10−39 cm2/water molecule.
  • Thumbnail Image
    ItemOpen Access
    Search for an anomalous excess of charged-current electron neutrino interactions with the MicroBooNE detector
    (Colorado State University. Libraries, 2022) Caro Terrazas, Ivan, author; Mooney, Michael R., advisor; Wilson, Robert J., committee member; Buchanan, Norm, committee member; Kirby, Michael, committee member
    MicroBooNE is a liquid argon time projection chamber detector designed to address the excess of low-energy electromagnetic events observed by the MiniBooNE detector. Electron neutrinos can create a wide variety of topologies when interacting with liquid argon; this analysis measures events without pions, both with (1eNp0π) and without (1e0p0π) visible protons. This thesis presents a first measurement of pionless charged-current electron neutrino interactions from the Booster Neutrino Beam at Fermilab in the MicroBooNE detector. A model based on the MiniBooNE result is used to quantify the strength of the electron neutrino excess. The analysis suggests that if an excess is present, it is not consistent with a simple scaling of the electronneutrino contribution to the flux. Combined, the 1eNp0π and 1e0p0π channels do not give a conclusive indication of the tested model, but separately they both disfavor the low-energy excess model at > 90% CL. The observation in the most sensitive 1eNp0π channel is below the prediction and is consistent with no excess. In the less sensitive 1e0p0π channel the observation at low energy is above the prediction, while overall there is agreement over the full energy spectrum.