Nuclear Commons^™

Crab Cavity Requirements For The Jefferson Lab Electron-Ion Collider, Salvador Isaac Sosa Güitrón

Physics Theses & Dissertations

An Electron-Ion Collider (EIC) has been proposed to be the next large facility to explore the dynamics of quarks and gluons inside nuclei. A conceptual design for a Jefferson Lab Electron-Ion Collider (JLEIC) is being developed. It is based on the CEBAF 12 GeV machine as a full energy electron beam injector. Two crucial requirements of JLEIC are high luminosity in the 10³⁴ cm^-2s^-1 range, and full acceptance detection of particles. The full acceptance requirement relies on having the beams collide at a relatively large crossing angle of 50 mrad. Such a large crossing angle, however, …

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 …

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 …

Determination Of The Neutron Beta-Decay Asymmetry Parameter A Using Polarized Ultracold Neutrons, Michael A.-P. Brown

Theses and Dissertations--Physics and Astronomy

The UCNA Experiment at the Los Alamos Neutron Science Center (LANSCE) is the first measurement of the β-decay asymmetry parameter A₀ using polarized ultracold neutrons (UCN). A₀ , which represents the parity-violating angular correlation between the direction of the initial neutron spin and the emitted decay electron’s momentum, determines λ = g_A /g_V , the ratio of the weak axial-vector and vector coupling constants. A high-precision determination of λ is important for weak interaction physics, and when combined with the neutron lifetime it permits an extraction of the CKM matrix element V_ud solely …

Magnetic Field Design To Reduce Systematic Effects In Neutron Electric Dipole Moment Measurements, James Ryan Dadisman

Theses and Dissertations--Physics and Astronomy

Charge-Conjugation (C) and Charge-Conjugation-Parity (CP) Violation is one of the three Sakharov conditions to explain via baryogenesis the observed baryon asymmetry of the universe (BAU). The Standard Model of particle physics (SM) contains sources of CP violation, but cannot explain the BAU. This motivates searches for new physics beyond the standard model (BSM) which address the Sakharov criteria, including high-precision searches for new sources of CPV in systems for which the SM contribution is small, but larger effects may be present in BSM theories. A promising example is the search for the electric dipole moment of the neutron (nEDM), which …

Probing The Low-X Gluon Helicity Distribution With Dijet Double Spin Asymmetries In Polarized Proton Collisions At √S = 510 Gev, Suvarna Ramachandran

Theses and Dissertations--Physics and Astronomy

The proton is a complex subatomic particle consisting of quarks and gluons, and one of the key questions in nuclear physics is how the spin of the proton is distributed amongst its constituents. Polarized deep inelastic scattering experiments with leptons and protons estimate that the quark spin contribution is approximately 30%. The limited kinematic reach of these experiments, combined with the fact that they are only indirectly sensitive to the electrically neutral gluon, means they can provide very little information about the gluon contribution to the spin of the proton. In contrast, hadronic probes, such as polarized proton collisions provide …

Electrons For Neutrinos Addressing Critical Neutrino-Nucleus Issues A Run Group Proposal Resubmission To Jefferson Lab Pac 46, A. Ashkenazy, R. Cruz Torres, S. Gilad, O. Hen, G. Laskaris, A. Papadopoulou, M. Patsyuk, A Schmidt, B. Schmookler, E. P. Segarra, F. Hauenstein, M. Hattawy, C. Hyde, M. Khachatryan, Sebastian Kuhn, L. B. Weinstein, E. O. Cohen, M. Duer, E. Piasetzky, D. Higinbotham, S. Stepanyan, H. Szumila-Vance, S. A. Wood, Christopher Marshall, K. Mahn, J. Morrison, L. Pickering, A. Beck, I. Korover, S. Mey-Tal Beck, A. El Alaoui, H. Hakobian, T. Mineeva, J. Miller, W. Brooks, M. Betancourt, T. Katori, I. Balossino, L. Barion, G. Ciullo, M. Contalbrigo, P. Lenisa, A. Movsisyan, L. L. Pappalardo, D. Watts, L. Zana, D. Ireland, D. Sokhan, N. Kalantarians, S. Li

Physics Faculty Publications

The extraction of neutrino mixing parameters from neutrino oscillation experiments relies on the reconstruction of the incident neutrino energy and knowledge of the neutrino-nucleus interaction cross section for various nuclei and incident neutrino energies. The energy reconstruction is done using the yield and kinematics of particles produced from neutrino interactions in nuclei. However, none of these energy reconstruction techniques have been tested experimentally using beams of known energy.

Because neutrinos and electrons are both leptons, they interact with nuclei in similar ways. We propose to measure electron scattering from a variety of targets at a range of beam energies in …

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 …

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 …

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.

Exclusive Production Of Phi Vector Meson During Hera-Ii, Brent Lawson

Honors Theses and Capstones

The Hadron Electron Ring Accelerator (HERA) in Germany, which ran from 1992 to 2007, is to date the only high energy electron and proton collider. The ZEUS detector at HERA measured the collisions of 27.5 GeV electrons with 920 GeV protons. Elastic vector meson production was measured during the first phase of HERA (HERA-I) from 1992 to 2000 before HERA was upgraded in 2003 (HERA-II) with increased luminosity. The goal of this project was to analyze data collected during the HERA-II run to identify and quantify the exclusive production of the  vector meson. Runs from the ZEUS experiment were …

Ψ(2s) Versus J/Ψ Suppression In Proton-Nucleus Collisions From Factorization Violating Soft Color, Yan-Qing Ma, Raju Venugopalan, Kazuhiro Watanabe, Hong-Fei Zhang

Physics Faculty Publications

We argue that the large suppression of the ψ(2S) inclusive cross section relative to the J/ψ inclusive cross section in proton-nucleus (p+A) collisions can be attributed to factorization breaking effects in the formation of quarkonium. These factorization breaking effects arise from soft color exchanges between charm-anticharm pairs undergoing hadronization and comoving partons that are long lived on time scales of quarkonium formation. We compute the short distance pair production of heavy quarks in the color glass condensate (CGC) effective field theory and employ an improved color evaporation model (ICEM) to describe their hadronization into quarkonium at large distances. The …

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 …

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 …

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 …

Measurement Of The Beam Asymmetry Σ And The Target Asymmetry T In The Photoproduction Of Ω Mesons Off The Proton Using Clas At Jefferson Laboratory, P. Roy, K. P. Adhikari, G. Charles, G. Gavalian, A. Klein, M. Mayer, Y. Prok, B. Torayev, J. Zhang, Z. W. Zhao

Physics Faculty Publications

he photoproduction of ω mesons off the proton has been studied in the reaction γp → pω using the CEBAF Large Acceptance Spectrometer (CLAS) and the frozen-spin target in Hall B at the Thomas Jefferson National Accelerator Facility. For the first time, the target asymmetry T has been measured in photoproduction from the decay ω → π⁺π⁻π⁰, using a transversely polarized target with energies ranging from just above the reaction threshold up to 2.8 GeV. Significant nonzero values are observed for these asymmetries, reaching about 30–40% in the third-resonance region. New measurements for the …

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 …

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 …

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 …

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.