Matching Items (20)

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Improving the Energy Reconstruction for Low Energy Supernova Neutrinos

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

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.

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Created

Date Created
  • 2020-05

Meson Decay in e p → e p K+ K- and e p → e p K+ K- π0 events

Description

In the quark model, meson states consisting of a quark/anti-quark pair must obey Poincaré symmetry. As a result of that symmetry, for meson total angular momentum J, parity P, and

In the quark model, meson states consisting of a quark/anti-quark pair must obey Poincaré symmetry. As a result of that symmetry, for meson total angular momentum J, parity P, and charge conjugation symmetry C, states with JPC= 0--, 0+-, 1-+, 2+-, 3-+, 4+-, … should not be observed. A meson observed experimentally with such quantum numbers would indicate a so-called “exotic” meson state. Exotic mesons can be multi-quark states like tetraquarks, a combination of two or more gluons known as glueballs, or a hybrid meson (qqg). Theories have suggested that three possible exotic meson states with the 1-+ quantum number: π1, η1, and η‘1,. However, no conclusive evidence for the existence of these three exotic states has been observed. This research will look for new states that decay to K* K final states with an emphasis on exotic mesons. An analysis of K+ K- π0 final states will be presented, where a restriction on the K - π0 invariant mass yields an unexpected enhancement in the K+ K- π0 spectrum.

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Created

Date Created
  • 2021-05

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Analysis of the Polarization Observables H & P for gamma p -> pi^+ n

Description

A search is underway to find baryon resonances that have been predicted, but yet remain unobserved. Nucleon resonances, due to their broad energy widths, overlap and must be disentangled in

A search is underway to find baryon resonances that have been predicted, but yet remain unobserved. Nucleon resonances, due to their broad energy widths, overlap and must be disentangled in order to be identified. Meson photoproduction observables related to the orientation of the spin of the incoming photon and the spin of the target proton are useful tools to deconvolve the nucleon resonance spectrum. These observables are particularly sensitive to interference between phases of the complex amplitudes. A set of these observables has been measured using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab with linearly-polarized photons having energies from 725 to 1575 MeV with polar angle values of cos(theta) between -0.8 and 0.9 and transversely-polarized protons in the Jefferson Lab FRozen Spin Target (FROST). By fitting neutron yields from gamma p -> pi^+ n over azimuthal scattering angle, the observables \H and P have been extracted. These observables manifest as azimuthal modulations in the yields for the double-polarization experiment. Preliminary results for these observables will be presented and compared with predictions provided by the SAID Partial-Wave Analysis Facility.

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Created

Date Created
  • 2018-05

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A Determination of the Partial Decay Width for the hb -> etab gamma Radiative Transition of Bottomonium

Description

Because of its massive nature and simple two-body structure, the heavy meson bottomonium (the flavorless bound state of the bottom quark and anti-quark) is among the simplest systems available for

Because of its massive nature and simple two-body structure, the heavy meson bottomonium (the flavorless bound state of the bottom quark and anti-quark) is among the simplest systems available for the study of the strong force and quantum chromodynamics (QCD)—a feature which has made it of special interest to particle physicists.

Despite being bound by the strong force, bottomonium exhibits a rich spectrum of resonances corresponding to excited states extremely analogous to that of positronium or even familiar atomic systems. Transitions between these levels are possible via the absorption or emission of either a photon, gluon, or gluons manifesting as light hadrons. The goal of this thesis was to establish a theoretical value for the currently unmeasured partial decay width for one such transition—the electromagnetic decay channel hb -> etab gamma. To this end, two methods were utilized.

The first approach relied on the presumption of a nonrelativistic constituent quark model interacting via a simple static potential, allowing for radial wave functions and energy eigenvalues to be obtained for the states of interest via the Schrödinger equation. Upon an application of the standard electromagnetic multipole expansion followed by a utilization of the electric dipole E1 decay width formula, a value of 57.7 ± 0.4 keV was obtained.

The second approach stemmed from the effective Lagrangian describing the bottomonium P to S electromagnetic transitions and relied on the presumption that a single coupling constant could be approximated as describing all nP to mS transitions regardless of spin. A value for this coupling constant could then be extracted from the 1P to 1S spin triplet data and used to predict the width for the singlet 1P to 1S transition. The partial decay width value found in this manner was 47.8 ± 2.0 keV.

Various other methods and models have established a predicted range of 35 to 60 keV for this partial decay width. As the values determined in this thesis fall within the expected range, they agree well with our current understanding of this electromagnetic transition and place further confidence on the expected range.

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Created

Date Created
  • 2016-12

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Feasibility of Studying Photoproduction of the ηC Meson and π1(2015) Hybrid Meson Candidate

Description

Preliminary feasibility studies for two possible experiments with the GlueX detector, installed in Hall D of Jefferson Laboratory, are presented. First, a general study of the feasibility of detecting the

Preliminary feasibility studies for two possible experiments with the GlueX detector, installed in Hall D of Jefferson Laboratory, are presented. First, a general study of the feasibility of detecting the ηC at the current hadronic rate is discussed, without regard for detector or reconstruction efficiency. Second, a study of the use of statistical methods in studying exotic meson candidates is outlined, describing methods and providing preliminary data on their efficacy.

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Created

Date Created
  • 2015-05

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Radioactive Isotope Identification

Description

A cloud chamber allows the naked eye to observe the beta- particle track produced from certain radioactive isotopes. These cloud chambers can be used during radiation education, as they allow

A cloud chamber allows the naked eye to observe the beta- particle track produced from certain radioactive isotopes. These cloud chambers can be used during radiation education, as they allow beta emitting isotopes to be seen. Within the apparatus, the white track that forms as a result of alcohol condensation, codenstates on the ions. These ions are left by electrons released from a radioactive isotope. In this experiment, a cloud chamber apparatus was placed under the conditions of a magnetic field. When a beta isotope is inserted into the chamber, the magnetic field should bend the beta-particle track. By measuring the radius of curvature of the electron tracks, the velocity is then observed. This velocity of the beta particle can then be used to calculate the kinetic energy, and ultimately can be utilized to identify the isotope.
The understanding of the methodology for identifying isotopes, nuclear waste cleanup can be effectively handled. In cases of environmental radioactivity, Geiger counters can only identify regions that are contaminated, as well as the number of radioactive particles per second within the region. Unfortunately they fail to determine the energy of each isotope. The identification of radioisotopes aid in the handling of cleanup and safety precautions.
This thesis focuses on the hardware and construction of the apparatus used, diving into electronics and particle physics. The software as well as future data collection and analysis will be conducted by Natjalia Bogdanovic, for defense in Spring 2020.

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Created

Date Created
  • 2019-05

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True muonium on the light front

Description

The muon problem of flavor physics presents a rich opportunity to study beyond standard model physics. The as yet undiscovered bound state (μ+μ-), called true muonium, presents a unique opportunity

The muon problem of flavor physics presents a rich opportunity to study beyond standard model physics. The as yet undiscovered bound state (μ+μ-), called true muonium, presents a unique opportunity to investigate the muon problem. The near-future experimental searches for true muonium will produce it relativistically, preventing the easy application of non-relativistic quantum mechanics. In this thesis, quantum field theory methods based on light-front quantization are used to solve an effective Hamiltonian for true muonium in the Fock space of |μ+μ-> , |μ+μ-γ> , |e+e->, |e+e-γ>, |τ+τ-> , and |τ+τ-γ> . To facilitate these calculations a new parallel code, True Muonium Solver With Front-Form Techniques (TMSWIFT), has been developed. Using this code, numerical results for the wave functions, energy levels, and decay constants of true muonium have been obtained for a range of coupling constants α. Work is also presented for deriving the effective interaction arising from the |γγ sector’s inclusion into the model.

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Created

Date Created
  • 2016

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Phenomenology of Topological Solitons

Description

In this dissertation, I present the results from my recent

investigations into the interactions involving topological defects, such as

magnetic monopoles and strings, that may have been produced in

In this dissertation, I present the results from my recent

investigations into the interactions involving topological defects, such as

magnetic monopoles and strings, that may have been produced in the early

universe. I performed numerical studies on the interactions of twisted

monopole-antimonopole pairs in the 't Hooft-Polyakov model for a range of

values of the scalar to vector mass ratio. Sphaleron solution predicted by

Taubes was recovered, and I mapped out its energy and size as functions of

parameters. I also looked into the production, and decay modes of $U(1)$ gauge

and global strings. I demonstrated that strings can be produced upon evolution

of gauge wavepackets defined within a certain region of parameter space. The

numerical exploration of the decay modes of cosmic string loops led to the

conclusions that string loops emit particle radiation primarily due to kink

collisions, and that their decay time due to these losses is proportional to

$L^p$, where $L$ is the loop length and $p \approx 2$. In contrast, the decay

time due to gravitational radiation scales in proportion to $L$, and I

concluded that particle emission is the primary energy loss mechanism for loops

smaller than a critical length scale, while gravitational losses dominate for

larger loops. In addition, I analyzed the decay of cosmic global string loops

due to radiation of Goldstone bosons and massive scalar ($\chi$) particles.

The length of loops I studied ranges from 200-1000 times the width of the

string core. I found that the lifetime of a loop is approximately $1.4L$. The

energy spectrum of Goldstone boson radiation has a $k^{-1}$ fall off, where $k$

is the wavenumber, and a sharp peak at $k\approx m_\chi/2$, where $m_\chi$ is

the mass of $\chi$. The latter is a new feature and implies a peak at high

energies (MeV-GeV) in the cosmological distribution of QCD axions.

Contributors

Agent

Created

Date Created
  • 2020

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Numerical Modeling and Experimental Studies on the Hydrodynamics and Heat Transfer of Silica Glass Particles

Description

Granular material can be found in many industries and undergo process steps like drying, transportation, coating, chemical, and physical conversions. Understanding and optimizing such processes can save energy as well

Granular material can be found in many industries and undergo process steps like drying, transportation, coating, chemical, and physical conversions. Understanding and optimizing such processes can save energy as well as material costs, leading to improved products. Silica beads are one such granular material encountered in many industries as a catalyst support material. The present research aims to obtain a fundamental understanding of the hydrodynamics and heat transfer mechanisms in silica beads. Studies are carried out using a hopper discharge bin and a rotary drum, which are some of the most common process equipment found in various industries. Two types of micro-glass beads with distinct size distributions are used to fill the hopper in two possible packing arrangements with varying mass ratios. For the well-mixed configuration, the fine particles clustered at the hopper bottom towards the end of the discharge. For the layered configuration, the coarse particles packed at the hopper bottom discharge first, opening a channel for the fine particles on the top. Also, parameters such as wall roughness (WR) and particle roughness (PR) are studied by etching the particles. The discharge rate is found to increase with WR, and found to be proportional to (Root mean square of PR)^(-0.58). Furthermore, the drum is used to study the conduction and convection heat transfer behavior of the particle bed with varying process conditions. A new non-invasive temperature measurement technique is developed using infrared thermography, which replaced the traditional thermocouples, to record the temperatures of the particles and the drum wall. This setup is used to understand the flow regimes of the particle bed inside the drum and the heat transfer mechanisms with varying process conditions. The conduction heat transfer rate is found to increase with decreasing particle size, decreasing fill level, and increasing rotation speed. The convection heat transfer rate increased with increasing fill level and decreasing particle size, and rotation speed had no significant effect. Due to the complexities in these systems, it is not always possible to conduct experiments, therefore, heat transfer models in Discrete Element Method codes (MFIX-DEM: open-source code, and EDEM: commercial code) are adopted, validated, and the effects of model parameters are studied using these codes.

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Created

Date Created
  • 2020

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Statistical Analysis of 3D-DEM for Steady State Conduction Heat Transfer in a Rotary Drum

Description

The current research is based on the principles of three-dimensional discrete element method (3D – DEM) through simulations, by using heat transfer models in EDEM, to investigate the effects of

The current research is based on the principles of three-dimensional discrete element method (3D – DEM) through simulations, by using heat transfer models in EDEM, to investigate the effects of fill level, rotation rate and particle size on the steady-state conduction heat transfer in rotary drums. The high heat and mass transfer rates obtained through rotary drums make them very useful for powder mixing and heating processes in metallurgical, cement, mining, pharmaceutical, detergent and other particulate processing applications. However, these complex processes are difficult to model and operate since the particles can have a wide range of properties, and there is currently no way to predict the optimal operating conditions for a given material.

Steady-state heat transfer by conduction forms the basis for understanding other steady-state and unsteady-state heat transfer in a rotary drum – conduction, convection and radiation. Statistical analysis is carried out to determine the effects of these process parameters and find optimal operating conditions, which will thereby improve the heat transfer efficiency in rotary drums. A stainless-steel drum with a diameter of 6 inches and a length of 3 inches was modeled in EDEM with silica beads of sizes 2 mm, 3 mm and 4 mm at fill levels of 10%, 17.5% and 25%, and at rotation rates of 2 rpm, 5 rpm and 10 rpm. It was found that the heating uniformity increased with decreasing particle size, decreasing fill level and increasing rotation rate. This research is the first step towards studying the other heat transfer modes and various other process parameters. Better understanding of the various heat transfer modes, when used in combination for heating the particles, will be beneficial in improving the operating efficiency, reducing material costs and leading to significant energy conservation on a global scale.

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Agent

Created

Date Created
  • 2020