Physical Sciences and Mathematics Commons^™

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 …

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 …

Enigma - Ongoing Development Towards Novel Beta-Decay Spectroscopy Station At Isolde, Philipp Wagenknecht

Masters Theses

Beta decay and collinear laser spectroscopy are proven efficient tools to study nuclear structure far from stability. Two areas of significance are investigations into nuclear deformation and shape coexistence, as well as delayed neutron emissions used in nuclear energy applications. This contribution presents the ongoing development towards a novel beta-decay spectroscopy station for the VITO experiment at CERN’s radioactive ion beam facility ISOLDE. The setup will utilize both collinear laser spectroscopy and beta-decay spectroscopy to measure the energy and spin-parities of the ground and excited states of radioactive beams. Initial designs of the support structure, magnetic field, and detector array …

Transverse Energy Analysis In Small Collision Systems, Alexander L. Aukerman

Masters Theses

Heavy Ion Collisions performed in the LHC at Cern are capable of generating a new phase of nuclear matter known as the Quark Gluon Plasma. In addition to running heavy ion collisions, the detectors dedicated to studying the QGP perform collisions utilizing smaller collision systems for the sake of comparing key measurements associated with the creation of a QGP. The transverse energy of the particles generated from the collision is one such key measurement. For the sake of comparison an analysis is performed on the transverse energy measurements taken from proton-proton collisions.

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 …

An Overview Of Approaches To Nuclear Security In Ghana, Raymond Agalga, Paul Atta Amoah, Daniel Nii Adjei, Daniel Frederick Charles, Emmanuel Ofori Darko

International Journal of Nuclear Security

Ghana has significantly improved its nuclear security infrastructure over the years. However, as threats increase by the day and new applications of nuclear and radiological technology are designed and implemented, Ghana must develop a rigid and comprehensive approach to mitigating the negative impacts on its nuclear security while improving prevention, detection, and deterrence of nuclear and radiological terrorism within its geographical space. This paper overviews the approaches adopted by Ghana to build a strong nuclear security regime within the past decade. These include improving legal frameworks for nuclear security by establishing an independent Nuclear Regulatory Authority; assessing nuclear security culture …

Design Of An Accelerator-Based Shielding Experiment At The Nasa Space Radiation Laboratory Relevant To Enclosed, Shielded Environments In Space, Lawrence H Heilbronn, Michael Sivertz, Adam Rusek, Charlie Pearson, Martha Clowdsley, Luis Castellanos, Natalie Mcgirl, Ashwin Srikrishna, Cary Zeitlin

Faculty Publications and Other Works -- Nuclear Engineering

Recent calculations indicate that the dose equivalent in an enclosed, shielded environment in a galactic cosmic ray field will increase or remain unchanged when shielding thickness increases beyond 20 to 30 g/cm2. This trend is seen out to 100 g/cm2, beyond which calculations were not run since depths greater than this are not envisioned for human missions in deep space. If these calculations are accurate, then an optimal shielding thickness (or narrow range of thicknesses) exists, with important implications for spacecraft and habitat design. Crucially, the calculation reveals a minimum dose equivalent value that cannot be reduced with added shielding, …