Matching Items (5)
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- Creators: Schmidt, Kevin E
- Creators: Ritchie, Barry
Description
The current observable universe is made of matter due to baryon/antibaryon asymmetry. The Deep Underground Neutrino Experiment is an international experiment through the Fermi National Accelerator Laboratory that will study neutrinos. In this study, the detection efficiency for low energy supernova neutrinos was examined in order to improve energy reconstruction for neutrino energies less than 40 MeV. To do this, supernova neutrino events were simulated using the LarSoft simulation package with and without background. The ratios between the true data and reconstructed data were compared to identify the deficiencies of the detector, which were found to be low energies and high drift times. The ratio between the true and reconstructed data was improved by applying the physical limits of the detector. The efficiency of the improved ratio of the clean data was found to be 93.2% and the efficiency of the improved ratio with the data with background was 82.6%. The study suggests that a second photon detector at the far wall of the detector would help improve the resolutions at high drift times and low neutrino energies.
ContributorsProcter-Murphy, Rachel Grace (Co-author) / Procter-Murphy, Rachel (Co-author) / Ritchie, Barry (Thesis director) / LoSecco, John (Committee member) / School of Earth and Space Exploration (Contributor) / Department of Physics (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
The spectra of predicted particles from elementary quark models (CQMs) are expansive, accurate for the low-lying spectra, but incomplete. The GlueX experiment at Jefferson Lab is a vehicle to study medium energy photoproduction of hadronic states. The primary goal of the GlueX collaboration is to study Quantum Chromodynamics (QCD, also known as the strong nuclear force) and the nature of quark confinement. The GlueX collaboration uses a polarized photon beam incident on a liquid hydrogen target (LH2) to investigate the aftermath of photon-proton interactions.The cascade baryons, denoted by Ξ, are defined by having two, second-generation, strange quarks with an additional first-generation light quark (u or d). Experimentally, few cascades have been discovered, which is the antithesis of what most models expect. The cascades have some favorable attributes but are difficult to detect because the production cross sections are small and direct production is unlikely. Fortunately, in the 12 GeV era of the GlueX experiment, there is sufficient energy, beam time and data analysis tools for the detection of excited cascade states and their properties.
From the reaction γp→K^+ K^+ Ξ^- π^0, the invariant mass spectra of Ξ^- π^0 system was surveyed for new possible resonances. The invariant mass spectrum has a strong Ξ(1530) signal with other smaller resonances throughout the spectrum. Preliminary cross sections for the Ξ(1530) that was photoproduced from the proton are presented at energies never before explored.
While the Ξ(1530) couples almost exclusively to the Ξπ channel, there is an easily identifiable Ξ(1690) signal decaying Ξπ. Through the use of a simultaneous fitting routing of the Ξ*- mass spectra, I was able to observe the Ξ(1690) decaying to the KΛ, as well as to the Ξ-π0 branch. With additional statistics, a measurement of the branching ratio should be possible.
Lastly, a partial wave analysis (PWA) was completed to verify that the total angular momentum of Ξ(1530) is J = 3/2 and consistent with having positive parity. Additionally, there is evidence of a potentially interesting feature slightly above the mass of the Ξ(1530) that should be more fully explored as new GlueX data becomes available.
ContributorsSumner, Brandon Christopher Lamont (Author) / Dugger, Michael (Thesis advisor) / Ritchie, Barry (Committee member) / Lebed, Richard (Committee member) / Alarcon, Ricardo (Committee member) / Arizona State University (Publisher)
Created2022
Description
In this dissertation two kinds of strongly interacting fermionic systems were studied: cold atomic gases and nucleon systems. In the first part I report T=0 diffusion Monte Carlo results for the ground-state and vortex excitation of unpolarized spin-1/2 fermions in a two-dimensional disk. I investigate how vortex core structure properties behave over the BEC-BCS crossover. The vortex excitation energy, density profiles, and vortex core properties related to the current are calculated. A density suppression at the vortex core on the BCS side of the crossover and a depleted core on the BEC limit is found. Size-effect dependencies in the disk geometry were carefully studied. In the second part of this dissertation I turn my attention to a very interesting problem in nuclear physics. In most simulations of nonrelativistic nuclear systems, the wave functions are found by solving the many-body Schrödinger equations, and they describe the quantum-mechanical amplitudes of the nucleonic degrees of freedom. In those simulations the pionic contributions are encoded in nuclear potentials and electroweak currents, and they determine the low-momentum behavior. By contrast, in this work I present a novel quantum Monte Carlo formalism in which both relativistic pions and nonrelativistic nucleons are explicitly included in the quantum-mechanical states of the system. I report the renormalization of the nucleon mass as a function of the momentum cutoff, an Euclidean time density correlation function that deals with the short-time nucleon diffusion, and the pion cloud density and momentum distributions. In the two nucleon sector the interaction of two static nucleons at large distances reduces to the one-pion exchange potential, and I fit the low-energy constants of the contact interactions to reproduce the binding energy of the deuteron and two neutrons in finite volumes. I conclude by showing that the method can be readily applied to light-nuclei.
ContributorsMadeira, Lucas (Author) / Schmidt, Kevin E (Thesis advisor) / Alarcon, Ricardo (Committee member) / Beckstein, Oliver (Committee member) / Erten, Onur (Committee member) / Arizona State University (Publisher)
Created2018
Description
This work presents analysis and results for the NPDGamma experiment, measuring
the spin-correlated photon directional asymmetry in the $\vec{n}p\rightarrow
d\gamma$ radiative capture of polarized, cold neutrons on a parahydrogen
target. The parity-violating (PV) component of this asymmetry
$A_{\gamma,PV}$ is unambiguously related to the $\Delta I = 1$ component of
the hadronic weak interaction due to pion exchange. Measurements in the second
phase of NPDGamma were taken at the Oak Ridge National Laboratory (ORNL)
Spallation Neutron Source (SNS) from late 2012 to early 2014, and then again in
the first half of 2016 for an unprecedented level of statistics in order to
obtain a measurement that is precise with respect to theoretical predictions of
$A_{\gamma,PV}=O(10^{-8})$. Theoretical and experimental background,
description of the experimental apparatus, analysis methods, and results for
the high-statistics measurements are given.
the spin-correlated photon directional asymmetry in the $\vec{n}p\rightarrow
d\gamma$ radiative capture of polarized, cold neutrons on a parahydrogen
target. The parity-violating (PV) component of this asymmetry
$A_{\gamma,PV}$ is unambiguously related to the $\Delta I = 1$ component of
the hadronic weak interaction due to pion exchange. Measurements in the second
phase of NPDGamma were taken at the Oak Ridge National Laboratory (ORNL)
Spallation Neutron Source (SNS) from late 2012 to early 2014, and then again in
the first half of 2016 for an unprecedented level of statistics in order to
obtain a measurement that is precise with respect to theoretical predictions of
$A_{\gamma,PV}=O(10^{-8})$. Theoretical and experimental background,
description of the experimental apparatus, analysis methods, and results for
the high-statistics measurements are given.
ContributorsBlyth, David (Author) / Alarcon, Ricardo O (Thesis advisor) / Ritchie, Barry G. (Committee member) / Comfort, Joseph R. (Committee member) / Schmidt, Kevin E (Committee member) / Arizona State University (Publisher)
Created2017
Description
I describe the first continuous space nuclear path integral quantum Monte Carlo method, and calculate the ground state properties of light nuclei including Deuteron, Triton, Helium-3 and Helium-4, using both local chiral interaction up to next-to-next-to-leading-order and the Argonne $v_6'$ interaction. Compared with diffusion based quantum Monte Carlo methods such as Green's function Monte Carlo and auxiliary field diffusion Monte Carlo, path integral quantum Monte Carlo has the advantage that it can directly calculate the expectation value of operators without tradeoff, whether they commute with the Hamiltonian or not. For operators that commute with the Hamiltonian, e.g., the Hamiltonian itself, the path integral quantum Monte Carlo light-nuclei results agree with Green's function Monte Carlo and auxiliary field diffusion Monte Carlo results. For other operator expectations which are important to understand nuclear measurements but do not commute with the Hamiltonian and therefore cannot be accurately calculated by diffusion based quantum Monte Carlo methods without tradeoff, the path integral quantum Monte Carlo method gives reliable results. I show root-mean-square radii, one-particle number density distributions, and Euclidean response functions for single-nucleon couplings. I also systematically describe all the sampling algorithms used in this work, the strategies to make the computation efficient, the error estimations, and the details of the implementation of the code to perform calculations. This work can serve as a benchmark test for future calculations of larger nuclei or finite temperature nuclear matter using path integral quantum Monte Carlo.
ContributorsChen, Rong (Author) / Schmidt, Kevin E (Thesis advisor) / Alarcon, Ricardo O (Committee member) / Beckstein, Oliver (Committee member) / Comfort, Joseph R. (Committee member) / Shovkovy, Igor A. (Committee member) / Arizona State University (Publisher)
Created2020