Nuclear Commons^™

Design And Characterization Of Multi-Spectral Underwater Beam-Port For Pool-Type Research Reactors, Meshari Mesfer Alqahtani

Doctoral Dissertations

“The beam-port is a cardinal facility at research reactors necessary for dry irradiation, testing and measurement experiments. The Missouri University of Science and Technology Reactor (MSTR) is one such reactor with a beam-port. Installation of additional beam-port in such reactor facilities can be prohibitive. A novel remedy to this is an underwater beam-port for pool-type reactors. The design and characterization of a conceptual underwater multi-spectral beam-port for neutron and gamma fluxes were completed for the MSTR. The neutron spectra from the MSTR were simulated using the Monte Carlo N-particle (MCNP). The determined neutron spectra were experimentally validated using SAND-II. The …

Characterization Of The Cylinderical Split Internal-Loop Photobioreactor With Scenedesmus Microalgae: Advanced Culturing, Modeling, And Hydrodynamics, Laith S. Sabri

Doctoral Dissertations

"Microalgae are fast growing photoynthetic microorganisms and it have very wide range of industrial applications such as biofuels and wastewater treatment. These cells can be grown in a wide variety of systems ranging from open culture systems (e.g., ponds) to closed culture systems of photobioreactor (e.g., airlift). The open culture systems exist in the external environment, and hence, are not intrinsically controllable. However, the microalgae production in enclosed photobioreactors faces prohibitively high production costs with special difficulty in reactor design and scale-up. The light availability and utilization efficiency in the photobioreactor in terms of design and scale-up consider as the …

Correlation Between Delay Time And Measured Concentration And Concentration Uncertainty By Neutron Activation Analysis, James Thomas Seman

Doctoral Dissertations

"For the last several decades, it has been apparent that new methods of identifying explosives can help investigators trace their origins. One way to identify an explosive is through the use of taggants: materials added to a product that encodes information about the product such as when it was manufactured.

This research investigates the survivability of a new identification taggant called the Nuclear Barcode that overcomes some of the downfalls that have been identified in prior taggants. The Nuclear Barcode encodes information as a unique combination of concentrations of rare earths (Ho, Eu, Sm, Lu, and Dy) and precious metals …

Neutronics Studies On The Nist Reactor Using The Ga Leu Fuel, Kyle A. Britton

Theses and Dissertations

The National Bureau of Standards Reactor (NBSR) located on the National Institute of Standards and Technology (NIST) Gaithersburg campus, is currently underway of fuel conversion from high enriched uranium (HEU) fuel to low enriched uranium (LEU) fuel. One particular challenging part of the conversion of the NBSR is the high average flux level (2.5×10¹⁴ n/cm²-s) required to maintain experimental testing capabilities of the reactor, without significant changes to the external structures of the reactor. Recently the General Atomics (GA) Training Research Isotopes General Atomics (TRIGA) fuel has shown some promising features as a LEU candidate for the …

Customized Multi-Group Cross Section Generation With Njoy For Discrete Ordinates Computed Tomography And Radiography Simulation, Steven Michael Wagstaff

Masters Theses

"The purpose of this work was to explore the creation of photoatomic multi-group cross section libraries to be used with a software package DOCTORS (Discrete Ordinates Computed TOmography and Radiography Simulator). This software solves the linear Boltzmann equation using the discrete ordinates method [1]. To create these libraries, NJOY2016 was used, creating both fine and broad energy multi-group cross section files. The cross section's accuracy was tested against an equivalent Monte Carlo simulation using MCNP6.

Two simulation geometries were used. The first, a cylindrical water phantom with a single source projection placed in front, simulating an X-ray radiography. The second …

Modulated Photothermal Radiometry: Detector Sensitivity Study And Experimental Setup, Jessica Nicole Seals

Masters Theses

"This thesis outlines the development of a system used for determining the surface thermal diffusivity of both non-irradiated and irradiated materials. The motivation for this work is to establish a modulated photothermal radiometry (PTR) system on the campus of Missouri University of Science and Technology. One of the main efforts described in this thesis is the design and construction of the physical apparatus. Along the way, it was necessary to perform a detailed sensitivity analysis of the system to determine whether the expected signal emitted from the sample falls within the bounds of detectivity for the HgCdTe (MCT) detector used …

Simulation Of Inverse Compton Scattering And Its Implications On The Scattered Linewidth, N. Ranjan, B. Terzić, G. A. Krafft, V. Petrillo, I. Drebot, L. Serafini

Physics Faculty Publications

Rising interest in inverse Compton sources has increased the need for efficient models that properly quantify the behavior of scattered radiation given a set of interaction parameters. The current state-of-the-art simulations rely on Monte Carlo-based methods, which, while properly expressing scattering behavior in high-probability regions of the produced spectra, may not correctly simulate such behavior in low-probability regions (e.g. tails of spectra). Moreover, sampling may take an inordinate amount of time for the desired accuracy to be achieved. In this paper, we present an analytic derivation of the expression describing the scattered radiation linewidth and propose a model to describe …

Measurements Of The Separated Longitudinal Structure Function Fl From Hydrogen And Deuterium Targets At Low Q2, V. Tvaskis, A. Tvaskis, I. Niculescu, D. Abbott, G. S. Adams, A. Afanasev, A. Ahmidouch, T. Angelescu, J. Arrington, A. Klein

Physics Faculty Publications

Structure functions, as measured in lepton-nucleon scattering, have proven to be very useful in studying the partonic dynamics within the nucleon. However, it is experimentally difficult to separately determine the longitudinal and transverse structure functions, and consequently there are substantially less data available in particular for the longitudinal structure function. Here, we present separated structure functions for hydrogen and deuterium at low four-momentum transfer squared, Q² < 1GeV², and compare them with parton distribution parametrization and k_T factorization approaches. While differences are found, the parametrizations generally agree with the data, even at the very low-Q² scale of …

Search For Three-Nucleon Short-Range Correlations In Light Nuclei, Z. Ye, P. Solvignon, D. Nguten, P. Aguilera, Z. Ahmed, H. Albataineh, K. Allada, B. Anderson, D. Anez, L. B. Weinstein

Physics Faculty Publications

We present new data probing short-range correlations (SRCs) in nuclei through the measurement of electron scattering off high-momentum nucleons in nuclei. The inclusive ⁴He/³He cross section ratio is observed to be both x and Q² independent for 1.5 < x < 2, confirming the dominance of two-nucleon short-range correlations. For x > 2, our data support the hypothesis that a previous claim of three-nucleon correlation dominance was an artifact caused by the limited resolution of the measurement. While 3N-SRCs appear to have an important contribution, our data show that isolating 3N-SRCs is significantly more complicated than for 2N-SRCs.

Center Of Mass Motion Of Short-Range Correlated Nucleon Pairs Studied Via The A(E, E'Pp) Reaction, Clas Collaboration, L. B. Weinstein, M. J. Amaryan, F. Hauenstein, A. Klein, S. E. Kuhn

Physics Faculty Publications

Short-range correlated (SRC) nucleon pairs are a vital part of the nucleus, accounting for almost all nucleons with momentum greater than the Fermi momentum (k_F). A fundamental characteristic of SRC pairs is having large relative momenta as compared to k_F, and smaller center of mass (c.m.) which indicates a small separation distance between the nucleons in the pair. Determining the c.m. momentum distribution of SRC pairs is essential for understanding their formation process. We report here on the extraction of the c.m. motion of proton-proton (pp) SRC pairs in carbon and, for the first …

Exclusive Photoproduction Of Πº Up To Large Values Of Mandelstam Variables S, T, And U With Clas, Clas Collaboration, M. C. Kunkel, M. J. Amaryan, S. Bültmann, G. Charles, C. E. Hyde, A. Klein, S E. Kuhn, J. Poudel, Y. Prok, L. B. Weinstein, Z. W. Zhao

Physics Faculty Publications

Exclusive photoproduction cross sections have been measured for the process γp→pπ⁰[e⁺e⁻(γ)] with the Dalitz decay final state using tagged photon energies in the range of E_γ= 1.275–5.425 GeV. The complete angular distribution of the final state π⁰ , for the entire photon energy range up to large values of t and u, has been measured for the first time. The data obtained show that the cross section dσ/dt , at mid to large angles, decreases with energy as s^{−6.89±0.26} . This is in agreement with the perturbative QCD quark …

Measurement Of The Q² Dependence Of The Deuteron Spin Structure Function G1 And Its Moments At Low Q² With Clas, Clas Collaboration, K. P. Adhikari, L. El Fassi, S E. Kuhn, M. J. Amaryan, S. Bültmann, G. Charles, Gail Dodge, N. Guler, C. E. Hyde, A. Klein, D. Payette, J. Poudel, Y. Prok, L. B. Weinstein, J. Zhang, Z. W. Zhao

Physics Faculty Publications

We measured the g₁ spin structure function of the deuteron at low Q², where QCD can be approximated with chiral perturbation theory (χPT). The data cover the resonance region, up to an invariant mass of W ≈ 1.9  GeV. The generalized Gerasimov-Drell-Hearn sum, the moment Γ^d₁ and the spin polarizability γ^d₀ are precisely determined down to a minimum Q² of 0.02  GeV² for the first time, about 2.5 times lower than that of previous data. We compare them to several χPT calculations and models. These results are the first in a …

Semi-Inclusive Πº Target And Beam-Target Asymmetries From 6 Gev Electron Scattering With Clas, S. Koirala, S E. Kuhn, D. Adikaram, M. J. Amaryan, S. Bültmann, G. Charles, Gail Dodge, N. Guler, M. Khachatryan, A. Klein, Y. Prok, L. B. Weinstein, Z. W. Zhao

Physics Faculty Publications

We present precision measurements of the target and beam-target spin asymmetries from neutral pion electroproduction in deep-inelastic scattering (DIS) using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. We scattered 6-GeV, longitudinally polarized electrons off longitudinally polarized protons in a cryogenic ¹⁴NH₃ target, and extracted double and single target spin asymmetries for ep → e′π⁰X in multidimensional bins in four-momentum transfer (1.0 < Q² < 3.2 GeV²), Bjorken-x (0.12 < x < 0.48), hadron energy fraction (0.4 < z < 0.7), transverse pion momentum (0 < P_T < 1.0 GeV), and azimuthal angle ϕ_h between the lepton scattering and hadron production planes. We extracted asymmetries as a function of both x and P_T, which provide access to transverse-momentum …

High Field Q Slope And The Effect Of Low-Temperature Baking At 3 Ghz, G. Ciovati, G. Eremeev, F. Hannon

Physics Faculty Publications

A strong degradation of the unloaded quality factor with field, called high field Q slope, is commonly observed above B_p ≅ 100 mT in elliptical superconducting niobium cavities at 1.3 and 1.5 GHz. In the present experiments several 3 GHz niobium cavities were measured up to and above B_p ≅ 100 mT. The measurements show that a high field Q slope phenomenon limits the field reach at this frequency, that the high field Q slope onset field depends weakly on the frequency, and that the high field Q slope can be removed by the typical empirical solution of …

Quantum Monte Carlo Calculations Of Weak Transitions In A=6-10 Nuclei, S. Pastore, A. Baroni, S. Gandolfi, R. Schiavilla, R. B. Wiringa

Physics Faculty Publications

Ab initio calculations of the Gamow-Teller (GT) matrix elements in the β decays of ⁶He and ¹⁰C and electron captures in 7Be are carried out using both variational and Green's function Monte Carlo wave functions obtained from the Argonne v18 two-nucleon and Illinois-7 three-nucleon interactions, and axial many-body currents derived from either meson-exchange phenomenology or chiral effective field theory. The agreement with experimental data is excellent for the electron captures in ⁷Be, while theory overestimates the ⁶He and ¹⁰C data by ~2% and ~10%, respectively. We show that for these systems correlations in the nuclear …

Resonances From Lattice Qcd, Raúl A. Briceño

Physics Faculty Publications

The spectrum of hadron is mainly composed as shortly-lived states (resonance) that decay onto two or more hadrons. These resonances play an important role in a variety of phenomenologically significant processes. In this talk, I give an overview on the present status of a rigorous program for studying of resonances and their properties using lattice QCD. I explain the formalism needed for extracting resonant amplitudes from the finite-volume spectra. From these one can extract the masses and widths of resonances. I present some recent examples that illustrate the power of these ideas. I then explain similar formalism that allows for …

K± Production In Semi-Inclusive Deep Inelastic Scattering Using Transversely Polarized Targets And The Solid Spectrometer, John Arrington, Whitney Armstrong, Paul Reimer, Seamus Riordan, Junqi Xie, Zhihong Ye, Andrew Puckett, Haiyan Gao, Chao Gu, Xiaqing Li, Weizhi Xiong, Zhiwen Zhao, Fatiha Benmokhtar, Alexandre Camsonne, Jian-Ping Chen, Tianbo Liu, Miha Mihovilovič, Simon Širca, Mitra Shabestari, Mohammad Hattawy, Garth Huber, Abhay Despande, Klaus Dehmelt, Nils Feege, Thomas Hemmick, Krishna Kumar, Sanghwa Park, Jinlong Zhang, Chendi Shen, Fuyue Wang, Yi Wang

Physics Faculty Publications

We propose to perform the measurement of K^± production in the Semi-Inclusive Deep Inelastic Scattering (SIDIS) using both the transversely polarized proton (NH₃) target and the transversely polarized ³He target (as effective polarized neutron target) on the SoLID spectrometer. This measurement will be carried out in parallel with the already approved SoLID spectrometer. This measurement will be carried out in parallel with the already approved SoLID experiments which will measure the π^± production in SIDIS, including E12-10-006 with transversely polarized ³He target and E12-11-108 with a transversely polarized NH₃ target. We will perform the off-line analysis to extract …

Parton Distribution Functions On The Lattice And In The Continuum, Joseph Karpie, Kostas Orginos, Anatoly Radyushkin, Savvas Zafeiropoulos

Physics Faculty Publications

Ioffe-time distributions, which are functions of the Ioffe-time ν, are the Fourier transforms of parton distribution functions with respect to the momentum fraction variable x. These distributions can be obtained from suitable equal time, quark bilinear hadronic matrix elements which can be calculated from first principles in lattice QCD, as it has been recently argued. In this talk I present the first numerical calculation of the Ioffe-time distributions of the nucleon in the quenched approximation.

Study Of J/Ψ Photoproduction Off Deuteron, M. D. Baker, A. J. Freese, L. Guo, C. Hyde, Y. Ilieva, B. Mckinnon, P. Nadel-Turonski, M. Sargsian, V. Kubarovsky, S. Stepanyan, N. Zachariou, Z. W. Zhao

Physics Faculty Publications

Exclusive, near-threshold quasi-real photoproduction of J/ψ off the deuteron provides attractive opportunities to study interesting physics. Besides studying the gluonic structure of bound nucleons and the deuteron (in coherent production), studying the final-state interactions allows a direct access to the elementary J/ψN cross section. There is one measurement of the near-threshold quasi-elastic J/ψ production off the deuteron, however data on final-state interactions or of the coherent cross section do not exist. With its high luminosity and large acceptance, the CLAS12 detector is well suited to measure near-threshold photoproduction of J/ψ off the deuteron.

This is a proposal to measure the …

Scattering Processes And Resonances From Lattice Qcd, Raúl A. Briceño, Jozef J. Dudek, Ross D. Young

Physics Faculty Publications

The vast majority of hadrons observed in nature are not stable under the strong interaction; rather they are resonances whose existence is deduced from enhancements in the energy dependence of scattering amplitudes. The study of hadron resonances offers a window into the workings of quantum chromodynamics (QCD) in the low-energy nonperturbative region, and in addition many probes of the limits of the electroweak sector of the standard model consider processes which feature hadron resonances. From a theoretical standpoint, this is a challenging field: the same dynamics that binds quarks and gluons into hadron resonances also controls their decay into lighter …