Physics Commons^™

A Measurement Of Neutron Polarization And Transmission For The Nedm@Sns Experiment, Kavish Imam

Doctoral Dissertations

The D.O.E Nuclear Science Advisory Committee Long Range Plan has called for experimental programs to explore fundamental symmetry violations and their implications in nuclear, particle and cosmological physics. The neutron electric dipole moment experiment at the Spallation Neutron Source (nEDM@SNS) aims to search for new physics in the Time-reversal (T) and Charge-Parity (CP) symmetry violating sector by setting a new limit on the nEDM down to a few x 10^-28 e·cm using a novel cryogenic technique, which combines the unique properties of polarized Ultracold Neutrons (UCN), polarized ³He, and superfluid ⁴He. The experiment will employ a cryogenic …

Short Range Correlation Measurements In The Quasielastic Region With An 11 Gev Beam, Casey Morean

Doctoral Dissertations

Electron scattering is a significant means of studying internal high momentum
nucleon and quark distributions in nuclei. Thomas Jefferson National Accelerator
Facility (JLab) with its 11GeV beam is capable of studying high momentum nucleons
with unmatched precision. The role of short range nucleon configurations and
quark distributions is significant for understanding the dynamics of nuclei and their
underlying components. Scattering cross section measurements in the kinematic
regime x > 1, where the free nucleon is forbidden, are sensitive to high momentum
nucleons, which are believed to come from short range correlations (SRCs). SRCs are
strongly interacting, high momentum nucleons with a …

Tev-Scale Lepton Number Violation: 0Νββ Decay, The Origin Of Matter, And Energy Frontier Probes, Sebastian Urrutia Quiroga

Doctoral Dissertations

Lepton number violation (LNV) offers promising theoretical pathways to several unresolved problems in particle and nuclear physics and unveils a diverse range of phenomenology across different energy scales. TeV-scale LNV is especially relevant for both its experimental accessibility and its broad-ranging impact, making it a key area of interest for both theoretical and experimental physicists. In this thesis, we explore three distinct scenarios within the LNV research landscape. Our first analysis concerns the implications of TeV-scale LNV effects in thermal leptogenesis and its complementary sensitivity in neutrinoless double beta (0νββ) decay and collider experiments. We employed a simplified model to …

Sub-Chandrasekhar Type Ia Supernovae Scenarios With Increased Pathways For Neutronization, Fernando Hernan Rivas

Doctoral Dissertations

Type Ia supernovae are thermonuclear explosions of white dwarfs (WD), electron-degenerate cores of old intermediate mass stars(under 8$M_{\odot}$). Reaching energies of $10^{51}$\si{\erg}, they outshine whole galaxies as they synthesize and distribute most of the iron group elements (IGE; V, Cr, Mn, Fe, Co, Ni) into the interstellar medium, thus being one of the main agents in cosmic chemical evolution. Also, given their notably homogeneous lightcurves, they form the last step in the cosmic distance ladder outdistancing Cepheid variables by orders of magnitude. Though calibration of said lightcurves is dependent on a high number of confirmed events, the limits of statistical …

Fabrication, Measurements, And Modeling Of Semiconductor Radiation Detectors For Imaging And Detector Response Functions, Corey David Ahl

Doctoral Dissertations

In the first part of this dissertation, we cover the development of a diamond semiconductor alpha-tagging sensor for associated particle imaging to solve challenges with currently employed scintillators. The alpha-tagging sensor is a double-sided strip detector made from polycrystalline CVD diamond. The performance goals of the alpha-tagging sensor are 700-picosecond timing resolution and 0.5 mm spatial resolution. A literature review summarizes the methodology, goals, and challenges in associated particle imaging. The history and current state of alpha-tagging sensors, followed by the properties of diamond semiconductors are discussed to close the literature review. The materials and methods used to calibrate the …

Total Absorption Spectroscopy Of Mo-106 And Tc-106, Michael Cooper

Doctoral Dissertations

Total absorption spectroscopy is a method of gamma-ray spectroscopy that has gained prominence in the past several decades, as nuclear data revisions are performed on older nuclear data, which is often incomplete. A strong understanding of underlying nuclear data, particularly fission and beta decay data, is essential for nuclear reactors and nuclear fuel decay heat. This PhD work involves the analysis of fission fragments 106Mo [Mo-106] and 106Tc [Tc-106]. These neutron rich isotopes contribute upwards of 6% of the cumulative fission yield of 241Pu [Pu-241] fission, and 4% of 239Pu [Pu-239] fission. Prior data for these two fission fragments only …

Neutrino Physics At A Research Reactor: Backgrounds And Analysis, Blaine Alexander Heffron

Doctoral Dissertations

The field of neutrino physics has a rich history and is currently the subject of much active research. The discovery of neutrino oscillations led to the conclusion that neutrinos have mass which was in contradiction to the Standard Model. Now researchers are investigating a number of open questions regarding neutrino properties such as their mass values or the existence of CP violation in the weak interaction. In order to answer these questions experimental and analytical techniques of neutrino detection are becoming more advanced, entering into an era of precision neutrino detection.

Nuclear reactors as a source of antineutrinos have played …

Development Of A New High-Resolution Neutron Detector And Beta-Delayed Neutron Spectroscopy Of 24o., Shree K. Neupane

Doctoral Dissertations

An efficient neutron detection system with good energy resolution is needed to correctly characterize the decays of neutron-rich nuclei where beta-delayed neutron emission is a dominant decay mode. Precision neutron spectroscopy probes nuclear structure effects in neutron-rich nuclei and is essential to exploit the opportunities in new-generation radioactive beam facilities. A new high-resolution neutron detector, Neutron dEtector with Xn Tracking (NEXT), has been constructed, characterized, and tested in decay and reaction experiments. Its essential capability is the neutron interaction position localization, which enables improvement in energy resolution without compromising detection efficiency in the time-of-flight measurements. Neutron-gamma discrimination capability of NEXT …

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Constraining The 30p(P,Γ)31s Reaction Using 30p(D,Pγ)31p With Goddess, Rajesh Ghimire

Doctoral Dissertations

The ³⁰P(p,γ)³¹S reaction acts as a bottleneck for classical nova nucleosynthesis beyond A=30 in ONe novae, due in part to the long lifetime of ³⁰P (∼2.5 minutes) with respect to the timescale of a nova outburst. Also, the ³⁰P(p,γ)³¹S reaction rate directly affects the isotopic ratio of ³⁰Si/²⁸Si, which is an important nova identifier in the analysis of pre-solar grains. O/S, S/Al, O/P, and P/Al elemental abundance ratios can be used as nuclear thermometers for classical novae by constraining the ³⁰P(p,γ)³¹S reaction rate.

However, direct measurement of …

The Impact Of A Nuclear Disturbance On A Space-Based Quantum Network, Alexander Miloshevsky

Doctoral Dissertations

Quantum communications tap into the potential of quantum mechanics to go beyond the limitations of classical communications. Currently, the greatest challenge facing quantum networks is the limited transmission range of encoded quantum information. Space-based quantum networks offer a means to overcome this limitation, however the performance of such a network operating in harsh conditions is unknown. This dissertation analyzes the capabilities of a space-based quantum network operating in a nuclear disturbed environment. First, performance during normal operating conditions is presented using Gaussian beam modeling and atmospheric modeling to establish a baseline to compare against a perturbed environment. Then, the DEfense …

The Structure Of 71ni Via Beta-Delayed Neutron Spectroscopy Of 71co, Andrew Keeler

Doctoral Dissertations

Studies of beta decays can give insights into the underlying structure of the nucleus. In particular, decays of closed-shell and near-closed-shell nuclei can provide important benchmarks for structure models, which are used in simulations of r-process nucleosynthesis. This work reports on a study of beta decays of ⁷¹Co produced in an experiment that was carried out in October 2016 at MSU’s National Superconducting Cyclotron Laboratory (NSCL) using the Versatile Array of Neutron Detectors at Low Energy (VANDLE). In order to carry out this experiment, a novel position-sensitive scintillating detector was developed to enable the sub-nanosecond timing response that VANDLE …

Improving Sensitivities In 0𝒗ββ Decay Searches By Utilizing Pen As A Structural Scintillating Material, Brennan Theresa Hackett

Doctoral Dissertations

Neutrinoless double beta decay, 0nbb is currently the only experimental test to unambiguously determine the majorana nature of the neutrino. There is a large international effort to measure 0nbb decay, with several detector technologies being pursued. This dissertation will consider the LEGEND experiment (Large Enriched Germanium Experiment for Neutrinoless bb Decay), an international effort to measure 0nbb decay with ⁷⁶Ge as both the target isotope and the detecting material.

LEGEND has a 200 kg stage and a 1000 kg stage, each requiring extremely low levels of background radiation at Q_bb (E = 2.039 MeV). These ultra-low background levels …

Measurement Of Jet Constituent Yields In Pb-Pb Collisions At √Snn = 5.02 Tev Using The Alice Detector, Charles P. Hughes

Doctoral Dissertations

Hard partonic scatterings serve as an important probe of quark-gluon-plasma (QGP) properties. The properties of jets and their constituents can provide a tool for understanding the partonic energy loss mechanisms. Low momentum jets offer a unique window into partonic energy loss because they reconstruct the partons which have lost a significant amount of energy to the QGP medium. The main difficulty in studying low momentum jets in heavy ion collisions is the presence of a significant uncorrelated background of low momentum hadrons from soft processes. One way to deal with this background is to use jet- hadron correlations to fit …

Calibration Of The Lux-Zeplin Dual-Phase Xenon Time Projection Chamber With Internally Injected Radioisotopes, Christopher D. Nedlik

Doctoral Dissertations

Self-shielding in ton-scale liquid xenon (LXe) detectors presents a unique challenge for calibrating detector response to interactions in the detector's innermost volume. Calibration radioisotopes must be injected directly into the LXe to reach the central volume, where they must either decay away with a short half life or be purified out. We present an overview of, and results from, the prototype source injection system (SIS) developed at the University of Massachusetts Amherst for the LUX-ZEPLIN experiment (LZ). The SIS is designed to refine techniques for the injection and removal of precise activities of various calibration radioisotopes that are useful in …

Beta-Delayed Neutron Emission Spectroscopy In The 78ni Region And Development Of Yso-Based Implantation Detector, Maninder Singh

Doctoral Dissertations

Decays of Cu isotopes provide a laboratory to study the properties for nearly doubly-magic nuclei with a significant neutron excess which are also relevant for the r-process models. The beta-decay properties of doubly-magic ⁷⁸Ni (N=50) are imprinted in the neighboring Cu decay, nuclei with a single proton outside the Z=28 core. The investigated isotopes ^79,80,81Cu are strong beta-delayed neutron precursors, suggesting that their decay strength distribution lies above neutron separation energies in ^79,80,81Zn daughters.

For decay studies, a segmented scintillator YSO (Y₂SiO₅ : Ce doped) based implantation detector was developed at the University of …

Tokamak 3d Heat Load Investigations Using An Integrated Simulation Framework, Thomas Looby

Doctoral Dissertations

Reactor class nuclear fusion tokamaks will be inherently complex. Thousands of interconnected systems that span orders of magnitude in physical scale must operate cohesively for the machine to function. Because these reactor class tokamaks are all in an early design stage, it is difficult to quantify exactly how each subsystem will act within the context of the greater systems. Therefore, to predict the engineering parameters necessary to design the machine, simulation frameworks that can model individual systems as well as the interfaced systems are necessary. This dissertation outlines a novel framework developed to couple otherwise disparate computational domains together into …

The Upgraded Measurement Of The Neutron Lifetime Using The In-Beam Method, Jimmy P. Caylor

Doctoral Dissertations

Precision measurements of neutron beta decay can provide answers to some of the most fundamental questions in particle physics, astrophysics and cosmology. Neutron beta decay is the simplest semi-leptonic decay; therefore, it provides a clean test of the charged current sector of the Standard Model (SM). A precise measurement of the neutron lifetime and λ, the ratio of axial vector and vector coupling constants of the weak interaction, allows for a determination of the Cabibbo-Kobayashi-Moskawa (CKM) matrix element V_ud that is free from nuclear structure effects. The SM predicts that the CKM matrix is unitary; therefore, the measurement of …

Measurement Of Neutrino-Induced Neutron Production In Lead, Brandon J. Becker

Doctoral Dissertations

The COHERENT Collaboration is an experimental effort to make the first measurement of coherent elastic neutrino-nucleus scattering (CE𝜈NS). The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory provides an intense, timed source of neutrinos from the decay of pions and muons produced during the spallation of mercury by 1 GeV protons generated in a particle accelerator. COHERENT seeks to make an unambiguous measurement by using a variety of low-threshold detectors capable of measuring the low-energy nuclear recoils resulting from CE𝜈NS interactions. This already challenging task is further complicated with the presence of backgrounds. Consequently, we must seek to reduce …

Study Of One-Nucleon Transfer Reactions, Jerome Mathew Kovoor

Doctoral Dissertations

The structure of nuclei away from the line of stability and near the driplines in the nuclear chart has been of huge interest since the arrival of radioactive ion beam facilities. The properties of nuclei evolve as a function of proton and neutron numbers and understanding the mechanisms behind this is one of the keys to explaining the strong nuclear force. Single-nucleon transfer reactions using deuteron targets are powerful probes of nuclear structure when the emitted proton or neutron is measured with high fidelity.

A variety of structure phenomena are observed in the beryllium isotopes marking them particularly attractive for …

A High Rate Pixelated Neutron Detector For Neutron Reflectometry At The Spallation Neutron Source, Su-Ann Chong

Doctoral Dissertations

This work presents the development of a high-rate 6Li-based pixelated neutron detector for neutron reflectometry instruments at the Spallation Neutron Source (SNS), Oak Ridge National Laboratory. The current detector technology falls short on the instrument requirements, particularly on the counting rate capability. This detector was designed specifically to overcome the limitation in counting rate by having a fully pixelated design from neutron conversion layer to photodetector and readout system. For the neutron converting layer, a 6Li-based neutron scintillator was used. Each scintillator element was coupled to a photodetector, in this case, a silicon photomultiplier (SiPM). The output of each SiPM …

Electroweak Interactions And Fundamental Symmetries In Light Nuclei With Short-Range Effective Field Theories, Zichao Yang

Doctoral Dissertations

Effective field theories(EFTs) are powerful tools to study nuclear systems that display separation of scales. In this dissertation, we present halo EFT results for the $\beta$-delayed proton emission from $^{11}$Be, and pionless EFT results for three-nucleon systems. Halo nuclei are simply described by a tightly bound core and loosely bound valence nucleons. Using the halo EFT, we calculate the rate of the rare decay $^{11}$Be, which is a well-known halo nucleus, into $^{10}\text{Be} + p +e^- + \bar{\nu}_e$. We assume a shallow $1/2 ^+$ resonance in the $^{10}$Be$-p$ system with an energy consistent with a recent experiment by Ayyad {\it …

Production Of Protactinium-229 Via Deuteron Irradiation Of Thorium-232, Naser Burahmah

Doctoral Dissertations

²²⁵Ac [Actinium-225] is a promising radionuclide for targeted alpha therapy of cancer. ²²⁹Pa can lead to the production of ²²⁹Th [Thorium-229] and ²²⁵Ac [Actinium-225]. Deuteron bombardment on natural thorium targets has been investigated to measure cross sections of protactinium isotopes. In this work, ²²⁹Pa [Protactinium-229] excitation function was measured via deuteron energies up to 50 MeV [Mega electron volt] of thin thorium foils. The irradiation took place at Lawrence Berkeley National Laboratory’s (LBNL) 88-Inch Cyclotron. The target processing and analysis were performed at Oak Ridge National Laboratory (ORNL). The target consisted of 4 thin foils …

In Situ Cosmogenic Backgrounds In The Majorana Demonstrator, Andrew Lopez

Doctoral Dissertations

Neutrino-less double-beta decay is a proposed type of radioactive decay that, if observed, could answer several outstanding physics questions, such as "Is the neutrino its own antiparticle otherwise known as a Majorana particle?", "What is the mass of the neutrino?", and "What is the neutrino mass hierarchy?" As technology and experimental techniques improve, the sensitivity of experiments looking for rare events becomes more dependent on the backgrounds. Some of these backgrounds can be reduced using shielding techniques such as implementing a veto system, selecting radiopure components, and conducting the experiment deep underground. However some amount of cosmogenically induced backgrounds remain …

Towards Neutron Transformation Searches, Joshua L. Barrow

Doctoral Dissertations

To probe the origins of the baryon asymmetry, baryon number violation, the last unconfirmed Sakharov condition, must be definitively observed experimentally. Similarly, the nature of dark matter is currently unknown, and calls out for new candidates to be investigated. Each of these issues can be considered through the study of neutron transformations.

Some rare baryon number violating processes, such as neutron-antineutron transformations, are expected to probe baryogenesis. Here, I show progress on this discovery target through construction of more accurate Monte Carlo models, the design of future detectors, creation of more complete atmospheric neutrino background simulations, and use of automated …

Study Of 134in Beta-Delayed Neutron Emission And Development Of A New Generation Neutron Detector, Joseph Heideman

Doctoral Dissertations

Beta-delayed neutron emission in very neutron-rich nuclei plays an essential role in nuclear structure and the understanding of the astrophysical r-process. A complete description of this process requires knowledge of both steps, beta decay and neutron emission. A leading theory poses the intermediate daughter nucleus to behave as a compound nucleus. The conditions for beta-delayed neutron emission of 134In are not well described by the assumptions in the neutron pandemonium hypothesis, therein providing a unique case to this process due to the proximity to 132Sn. Single-particle states in 133Sn obvserved after neutron emission have dissimilar shell occupancy compared to neutron-hole …

Probability Distribution Of Equations Of State For Astrophysical Simulations, Xingfu Du

Doctoral Dissertations

The detection of gravitational wave during the neutron star merger event GW170817 greatly enhanced our ability to probe the interiors of neutron stars. Future measurements of similar events will put further constraints to the equation of state (EOS) of nuclear matter. Also, uncertainties in the EOS create variations in the results of astrophysical simulations of core-collapse supernovae and neutron star mergers. In order to quantify the uncertainties, we construct a probability distribution of equations of state (EOSs). We create a new EOS which respects experimental, observational and theoretical constraints on the nature of matter in various density and temperature regimes. …

Characterization Of Neutron Irradiated Accident Tolerant Nuclear Fuel Cladding Silicon Carbide & Radiation Detector Deadtime, Bader Almutairi

Doctoral Dissertations

“In part I, the pulse shape characteristics generated by a Geiger Muller (GM) detector and recorded by an oscilloscope manually, were investigated. The objective of part I was (1) to find a correlation between pulse shape and the operating voltage; and (2) to assess if pulse shape properties followed distinct patterns comparable to detector deadtime findings reported by a previous study. It was observed that (1) there is a strong correlation between pulse shape and operating voltage, and (2) pulse shape falls in three distinct regions similar to detector deadtime. Furthermore, parts II and III are companions and share the …

Applications Of Machine Learning In Nuclear Imaging And Radiation Detection, Shaikat Mahmood Galib

Doctoral Dissertations

"The main focus of this work is to use machine learning and data mining techniques to address some challenging problems that arise from nuclear data. Specifically, two problem areas are discussed: nuclear imaging and radiation detection. The techniques to approach these problems are primarily based on a variant of Artificial Neural Network (ANN) called Convolutional Neural Network (CNN), which is one of the most popular forms of 'deep learning' technique.

The first problem is about interpreting and analyzing 3D medical radiation images automatically. A method is developed to identify and quantify deformable image registration (DIR) errors from lung CT scans …

Development Of A Switchable Radioisotope Generator, Kyle Mitchell Paaren

Doctoral Dissertations

The Switchable Radioisotope Generator utilizes alpha-induced reactions to produce a combination of photons, neutrons, and protons with varying fluxes dependent on target materials and source geometry. The activity/strength of the secondary radiation is further controlled by manipulating the number of alpha particles that can interact with the target material(s). Analytical equations were solved to confirm secondary radiation production from target materials using average cross sections from TENDL data. TENDL and JENDL data was confirmed by analytically solving for the total alpha-induced cross sections. This information was used to produce the provisional and utility Patent No: US20190013109A1. TENDL data was then …

Alpha Radiation Studies And Related Backgrounds In The Darkside-50 Detector, Alissa Monte

Doctoral Dissertations

DarkSide-50 is the current phase of the DarkSide direct dark matter search program, operating underground at the Laboratori Nazionali del Gran Sasso in Italy. The detector is a dual-phase argon Time Projection Chamber (TPC), designed for direct detection of Weakly Interacting Massive Particles (WIMPs), and housed within a veto system of liquid scintillator and water Cherenkov detectors. Since switching to a target of low radioactivity argon extracted from underground sources in April 2015, the background is no longer dominated by naturally occurring 39Ar. However, alpha backgrounds from radon and its daughters remain, both from the liquid argon bulk and internal …