Physics Commons^™

Measurement Of Single- And Double-Spin Asymmetries In Deep Inelastic Pion Electroproduction With A Longitudinally Polarized Target, H. Avakian, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

We report the first measurement of the transverse momentum dependence of double-spin asymmetries in semi-inclusive production of pions in deep-inelastic scattering off the longitudinally polarized proton. Data have been obtained using a polarized electron beam of 5.7 GeV with the CLAS detector at the Jefferson Lab (JLab). Modulations of single spin asymmetries over the azimuthal angle between lepton scattering and hadron production planes φ have been measured over a wide kinematic range in Bjorken x and virtual photon squared four-momentum Q². A significant nonzero sin2φ single spin asymmetry was observed for the first time indicating strong spin-orbit …

Implementation Of The Clas12 Htcc Into Gemc, Nathan A. Harrison

Master's Theses

No abstract provided.

Speciation And Spectroscopy Of The Uranyl And Tetravalent Plutonium Nitrate Systems: Fundamental Studies And Applications To Used Fuel Reprocessing, Nicholas A. Smith

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation explores the use of UV-Visible spectroscopy and Time Resolved Laser Induced Fluorescence spectroscopy as near real time process monitors of uranium and plutonium concentrations in aqueous reprocessing trains. The molar absorptivities and linear ranges of these metals were investigated under total nitrate and acid concentrations similar to those found in current reprocessing systems. Concurrent to this, a new multiple wavelength monitor was derived that is capable of determining the total nitrate concentration spectroscopically. This method uses the uranium absorbance spectrum to calculate the nitrate concentration in solution. When used as part of an Advanced Safeguard suite, this technique …

Tensor Correlations Measured In 3He(E,E',Pp)N, H. Baghdasaryan, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

We have measured the ³He(e, e', pp)n reaction at an incident energy of 4.7 GeV over a wide kinematic range. We identified spectator correlated pp and pn nucleon pairs by using kinematic cuts and measured their relative and total momentum distributions. This is the first measurement of the ratio of pp to pn pairs as a function of pair total momentum p_tot. For pair relative momenta between 0.3 and 0:5 GeV / c, the ratio is very small at low p_tot and rises to approximately 0.5 at large p_tot. This …

Tensor Correlations Measured In 3he(E,E' Pp)N, H. Baghdasaryan, L. B. Weinstein, J. M. Laget, K. P. Adhikarii, M. Aghasyan, M. Amarian, M. Anghinolfi, H. Avakian, J. Ball, M. Battaglieri, R. P. Bennett, S. Bültmann, G. E. Dodge, C. E. Hyde, A. Klein, S. E. Kuhn, M. Mayer, C. Nepali, F. Sabatié, H. Seraydaryan, Z. W. Zhao

Physics Faculty Publications

We have measured the ³He(e,e' pp)n reaction at an incident energy of 4.7 GeV over a wide kinematic range. We identified spectator correlated pp and pn nucleon pairs by using kinematic cuts and measured their relative and total momentum distributions. This is the first measurement of the ratio of pp to pn pairs as a function of pair total momentum p_tot. For pair relative momenta between 0.3 and 0.5 GeV/c, the ratio is very small at low p_tot and rises to approximately 0.5 at large ptot. This shows the dominance of tensor over …

Determination Of The Axial-Vector Weak Coupling Constant With Ultracold Neutrons., J. Liu, Michael P. Mendenhall, Anthony T. Holley, Henning O. Back, Thomas J. Bowles, Leah J. Broussard, Richard Carr, Stephen Clayton, Scott Currie, Bradley W. Filippone, A. Garcı́A, Peter Geltenbort, Kevin P. Hickerson, J. Todd Hoagland, Gary E. Hogan, B. Hona, Takeyasu M. Ito, Chenyu Liu, Mark Makela, Russell R. Mammei, J.W. Martin, Daneil Melconian, Charles L. Morris, Robert W. Pattie, A. Pérez Galván, Margaret L. Pitt, Bradley Plaster, John C. Ramsey, R. Rios, R. Russell, Andy Saunders, Susan J. Seestrom, Walter E. Sondheim, E. Tatar, Robert B. Vogelaar, Brittany Vorndick, Christopher Wrede, H. Yan, Albert R. Young

Robert W. Pattie Jr.

Two-Loop Soft Anomalous Dimensions For Single Top Quark Associated Production With A W- Or H-, Nikolaos Kidonakis

Faculty and Research Publications

I present results for the two-loop soft anomalous dimensions for associated production of a single top quark with a W boson or a charged Higgs boson. The calculation uses expressions for the massive cusp anomalous dimension, which are presented in different forms, and it allows soft-gluon resummation at next-to-next-to-leading-logarithm (NNLL) accuracy. From the NNLL resummed cross section I derive approximate NNLO cross sections for bg→tW- and bg→tH- at LHC energies of 7, 10, and 14 TeV.

Absorption Of The Ω And Φ Mesons In Nuclei, M. Wood, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

Because of their long lifetimes, the ω and φ mesons are the ideal candidates for the study of possible modifications of the in-medium meson-nucleon interaction through their absorption inside the nucleus. During the E01-112 experiment at the Thomas Jefferson National Accelerator Facility, the mesons were photoproduced from ²H, C, Ti, Fe, and Pb targets. This Letter reports the first measurement of the ratio of nuclear transparencies for the e⁺e^- channel. The ratios indicate larger in-medium widths compared with what have been reported in other reaction channels. The absorption of the ω meson is stronger than that …

Differential Cross Sections And Recoil Polarizations For The Reaction Γp→K+Σ0, B. Dey, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

High-statistics measurements of differential cross sections and recoil polarizations for the reaction γp → K⁺Σ⁰ have been obtained using the CLAS detector at Jefferson Lab. We cover center-of-mass energies (√s) from 1.69 to 2.84 GeV, with an extensive coverage in the K⁺ production angle. Independent measurements were made using the K⁺pπ⁻(γ) and K⁺p(π⁻, γ ) final-state topologies, and were found to exhibit good agreement. Our differential cross sections show good agreement with earlier CLAS, SAPHIR, and LEPS results, while offering better statistical precision and …

Differential Cross Sections And Recoil Polarizations For The Reaction Γp→K+Σ0, B. Dey, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

High-statistics measurements of differential cross sections and recoil polarizations for the reaction γp → K⁺Σ⁰ have been obtained using the CLAS detector at Jefferson Lab. We cover center-of-mass energies ( √s) from 1.69 to 2.84 GeV, with an extensive coverage in the K⁺ production angle. Independent measurements were made using the K⁺pπ⁻(γ) and K⁺p(π⁻, γ) final-state topologies, and were found to exhibit good agreement. Our differential cross sections show good agreement with earlier CLAS, SAPHIR, and LEPS results, while offering better …

Neutron Flux And Energy Characterization Of A Plutonium-Beryllium Isotopic Neutron Source By Monte Carlo Simulation With Verification By Neutron Activation Analysis, Zachary R. Harvey

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this research was to characterize the neutron energy distribution and flux emitted from the UNLV plutonium-beryllium source, serial number MRC-N-W PuBe 453. This was accomplished through the use of the MCNPX/5 Monte-Carlo particle transport code to simulate radiation interactions within the physical environment of the source and its surroundings. The moderating drum currently containing the source as well as all of the sampling ports were accurately modeled in MCNPX/5. This geometry was then used to simulate the neutron interactions taking place in these geometries. The results of the simulations were then verified by the use of specifically …

Feasibility And Conceptual Design Of A C.W. Positron Source At Cebaf, Serkan Golge

Physics Theses & Dissertations

A feasibility study of a CW positron source for the 12 GeV upgrade at Jefferson Lab (JLAB) is provided. The proposed ≥ 100 nA Continuous Wave (CW) positron source at JLAB has several unique and challenging characteristics: high current incident electron beam at 126 MeV with a high beam power (up to a MW); CW e−beam and CW e+ production. The multiple scattering is a dominant process when creating e+ in a target, which results a large phase space area of the emitted positrons. An admittance study was done at CEBAF to find the maximum phase space area, which is …

Particle-Γ Spectroscopy Of The (P,D-Γ)155Gd Reaction: Neutron Single-Quasiparticle States At N=91, J. M. Allmond, C. W. Beausang, J. O. Rasmussen, T. J. Ross, M. S. Basunia, L. A. Bernstein, D. L. Bleuel, W. Brooks, N. Brown, J. T. Burke, B. Darakchieva, K. Dudziak, K. E. Evans, P. Fallon, H. B. Jeppesen, J. Leblanc, S. R. Lesher, M. A. Mcmahan, D. A. Meyer, L. Phair, N. D. Scielzo, S. R. Stroberg, M. Wiedeking

Physics Faculty Publications

A segmented Si telescope and HPGe array is used to study the ¹⁵⁶Gd(p,d-γ)¹⁵⁵Gd direct reaction by d-γ and d-γ-γ coincidence measurements using 25-MeV protons. The present investigation is the first time that this N = 91 nucleus and the N = 90 region—which is known for a rapid change from vibrational to rotational character, several low-lying 0⁺ states in the even-even nuclei, and large Coriolis (ΔΩ = 1) plus ΔN = 2 mixing in the even-odd nuclei—have been studied by particle-γ coincidence following a direct reaction with light ions. Gamma-ray energies and branches, …

The Combined Effects Of Radio Frequency And Gamma Irradiation On P-Channel Mosfets, Joshua D. Daniel

Theses and Dissertations

The purpose of this research was to investigate the combined effects of continuous gigahertz radio frequency signals and gamma irradiation on the threshold voltage of metal oxide semiconductor field effect transistors. The combined effects of gigahertz radio frequency waves and gamma irradiation on electronics presents a new challenge in electronic warfare and little is known of the combined effect on threshold voltage damage and recovery. The Fairchild NDS352AP, a commonly used commercial device, was irradiated by a cobalt-60 source under a +5 V bias with and without a radio frequency signal applied to the gate. The threshold voltage was measured …

Design And Construction Of A Thermal Diffusion Cloud Chamber, Alexander Donoghue

Physics

This paper will cover the theory behind a thermal diffusion cloud chamber. In addition to that it will cover the process, thought and material used to construct two different cloud chambers. It will also discuss the effects of materials used in each chamber on the working of the chamber.

Identification Of Bottom Quark Jets In Pb+Pb Collisions In Alice At The Lhc, Brandon Boswell

Physics

In the near future, the Large Hadron Collider (LHC) will begin colliding lead ions together with energies high enough to produce a state of matter known as the Quark-Gluon Plasma (QGP). Simulations have shown that Bottom-quark-jets (B-jets) are expected to be produced in these collisions, and that these B-jets provide a useful probe into the nature of the QGP. The ALICE detector (A Large Ion Collider Experiment) at the LHC is designed to study the nature of the QGP. In this paper we investigate the effect of requiring that an electron be inside observed jets and how this improves the …

A Qcd Analysis Of Zeus Diffractive Data, S. Chekanov, M. Derrick, S. Magill, B. Musgrave, D. Nicholass, J. Repond, R. Yoshida, Margarita C. K. Mattingly, P. Antonioli, G. Bari, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, F. Cindolo, M. Corradi, G. Iacobucci, A. Margotti, R. Nania, A. Polini, S. Antonelli, M. Basile, M. Bindi, L. Cifarelli, A. Contin, S. De Pasquale, G. Sartorelli, A. Zichichi, D. Bartsch, I. Brock, H. Hartmann

Faculty Publications

ZEUS inclusive diffractive-cross-section measurements have been used in a DGLAP next-to-leading-order QCD analysis to extract the diffractive parton distribution functions. Data on diffractive dijet production in deep inelastic scattering have also been included to constrain the gluon density. Predictions based on the extracted parton densities are compared to diffractive charm and dijet photoproduction data. © 2010 Elsevier B.V.

Characterization Of Plutonium Particles Originating From The Bomarc Accident -1960, Richard Charles Gostic

UNLV Theses, Dissertations, Professional Papers, and Capstones

Within the U.S. arsenal, 32 accidents with nuclear weapons were reported between 1950 and 1980. One of these accidents occurred at McGuire AFB in 1960. A BOMARC missile armed with a nuclear warhead caught on fire and as a result the warhead was destroyed. Sub-millimeter particles consisting of weapons grade plutonium (WGPu) produced by this accident were distributed around the site and remained in the environment for 47 years. Soil cores known to contain WGPu particles produced by this accident were obtained. The particles were localized and removed from the soil with the aid of high resolution computed tomography. The …

Beyond The Born Approximation: A Precise Comparison Of E+P And E-P Elastic Scattering In The Cebaf Large Acceptance Spectrometer (Clas), Megh Raj Niroula

Physics Theses & Dissertations

How well we know the structure of the proton depends on our knowledge of the form factors of the proton. The ratio of the electromagnetic form factors of the proton measured by the Rosenbluth and the polarization transfer methods differ by a factor of 3 at four momentum transfer squared (Q²)=5.6 GeV². The two photon exchange (TPE) effect is the leading candidate to explain this discrepancy. The theoretical estimates of the TPE effect are model dependent so precise measurement is required to resolve this problem. The TPE effect can be measured in a model independent way by measuring …

Exclusive Π- Electro-Production From The Neutron In The Resonance Region, Jixie Zhang

Physics Theses & Dissertations

The study of baryon resonances is crucial to our understanding of nucleon structure. Although the excited states of the proton have been studied in great detail, there are very few data available for the neutron resonances because of the difficulty inherent in obtaining a free neutron target. To overcome this limitation, the spectator tagging technique was used in one of the CEBAF Large Acceptance Spectrometer (CLAS) collaboration experiments, Barely off-shell Nuclear Structure (BoNuS), in Hall-B at Jefferson Lab. We have constructed a radial time projection chamber (RTPC) based on the gaseous electron multiplier (GEM) technology to detect low momentum …

Nuclear Electromagnetic Currents In Chiral Effective Field Theory, Saori Pastore

Physics Theses & Dissertations

A nucleon-nucleon potential and consistent nuclear electromagnetic currents are derived in chiral effective field theory retaining pions and nucleons as explicit degrees of freedom. The calculation of the potential is carried out up to next-to-next-to leading order (N²LO), while the currents include up to N³LO corrections. The potential at N² LO and currents at N³LO consist of two-pion-exchange and contact contributions. The currents are then utilized to study a number of low-energy electromagnetic observables induced by magnetic dipole transitions, such as the deuteron and trinucleon magnetic moments and the np, nd and n …

Measurement Of Γ-Emission Branching Ratios For 154,156,158Gd Compound Nuclei: Tests Of Surrogate Nuclear Reaction Approximations For (N,Γ) Cross Sections, N. D. Scielzo

Physics Faculty Publications

The surrogate nuclear reaction method can be used to determine neutron-induced reaction cross sections from measured decay properties of a compound nucleus created using a different reaction and calculated formation cross sections. The reliability of (n,γ) cross sections determined using the Weisskopf-Ewing and ratio approximations are explored for the ^{155, 157}Gd(n,γ) reactions. Enriched gadolinium targets were bombarded with 22-MeV protons and γ rays were detected in coincidence with scattered protons using the Silicon Telescope Array for Reaction Studies/Livermore-Berkeley Array for Collaborative Experiments (STARS/LiBerACE) silicon and germanium detector arrays. The γ-emission probabilities for the ^{154, 156, …}

Time Dependent Channel Packet Calculation Of Two Nucleon Scattering Matrix Elements, Brian S. Davis

Theses and Dissertations

A new approach to calculating nucleon-nucleon scattering matrix elements using a proven atomic time-dependent wave packet technique is investigated. Wave packets containing centripetal barrier information are prepared in close proximity to nuclear well. This is accomplished by first using an analytic equation to determine the wave packets in a suitable intermediate asymptotic state where the centripetal barrier is negligible. Then, the split operator technique is used to propagate the wave packets back to their original positions under the full Hamiltonian. Here, one wave packet is held stationary while the other is allowed to evolve and explore the nuclear well. Scattering …

Nuclear Forensics: Measurements Of Uranium Oxides Using Time-Of-Flight Secondary Ion Mass Spectrometry (Tof-Sims), Wesley A. Schuler

Theses and Dissertations

Over the past decade, law enforcement, governmental and public agencies have been stymied by the threat of the trafficking of nuclear materials. During this time span, reports from the International Atomic Energy Agency of illicit trafficking have increased eightfold from 20 to 160. For this reason, nuclear forensics is a burgeoning science focused on the identification of seized special nuclear materials. Identification of these materials is based upon the wealth of information that can be obtained by applying multiple analytical and measurement technologies. All of the information gained from each sample can then be used to further characterize other samples …

Three Dimensional Positron Annihilation Momentum Measurement Technique (3dpamm) Applied To Measure Oxygen-Atom Defects In 6h Silicon Carbide, Christopher S. Williams

Theses and Dissertations

A three-dimensional Positron Annihilation Spectroscopy System (3DPASS) capable to simultaneously measure three-dimensional electron-positron (e--e+) momentum densities measuring photons derived from e--e+ annihilation events was designed and characterized. 3DPASS simultaneously collects a single data set of correlated energies and positions for two coincident annihilation photons using solid-state double-sided strip detectors (DSSD). Positions of photons were determined using an interpolation method which measures a figure-of-merit proportional to the areas of transient charges induced on both charge collection strips directly adjacent to the charge collection strips interacting with the annihilation photons. The subpixel resolution was measured for both double-sided strip detectors (DSSD) and …

Thermal Neutron Point Source Imaging Using A Rotating Modulation Collimator (Rmc), Nathan O. Boyce

Theses and Dissertations

This thesis demonstrates a previously untested capability of the Rotating Modulation Collimator (RMC) to image a point-like neutron source. The encouraging results, achieved using low-energy neutrons, provide motivation for further refinement and continued research with higher-energy neutrons. The detector and the masks on an existing RMC imaging system were exchanged to function with neutrons. The source in this research produced a poly-energetic spectrum of neutrons through the reaction. The source of alpha particles was a 72.7 mCi ²³⁹Pu source. The RMC detector was located 250 cm from the bare source and operated for three hours to generate a modulation …

In-Situ, Gate Bias Dependent Study Of Neutron Irradiation Effects On Algan/Gan Hfets, Janusz K. Mikina

Theses and Dissertations

AlGaN/GaN Heterostructure Field Effect Transistors (HFETs) have come under increased study in recent years due to their highly desirable material and electrical properties and survivability even during and after exposure to extreme temperature and radiation environments. In this study, unpassivated and SiN passivated Al_0.27Ga_0.73N/GaN HFETs were subjected to neutron radiation at 120 K. The primary focus of the research was the effects of neutron irradiation on drain current, gate leakage current, threshold voltage shift, gate-channel capacitance, and the effects of biasing the gate during irradiation. In-situ measurements were conducted on transistor current, gate-channel capacitance, and gate …

Uncertainty Quantification Of Multi-Component Isotope-Separation Cascade Model, Khoi D. Tran

Theses and Dissertations

Monte Carlo uncertainty quantification (UQ) capability has been added to a code for modeling multi-component steady-state isotope-separation enrichment cascades to characterize the propagation of uncertainties in input data that define the cascade and the feed. Random samples of error for every computational input are drawn from its individual uncertainty distribution and added to the inputs, creating a set of enrichment cascade problems with perturbed inputs. The set of problems is solved using the verified code. The cascade outputs are then characterized using the empirical cumulative distribution. The uncertainty output data are analyzed to gain new insights into the behaviors of …

Measurement Of Dijet Photoproduction For Events With A Leading Neutron At Hera, S. Chekanov, M. Derrick, S. Magill, B. Musgrave, D. Nicholass, J. Repond, R. Yoshida, Margarita C. K. Mattingly, P. Antonioli, G. Bari, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, F. Cindolo, M. Corradi, G. Iacobucci, A. Margotti, R. Nania, A. Polini, S. Antonelli, M. Basile, M. Bindi, L. Cifarelli, A. Contin, S. De Pasquale, G. Sartorelli, A. Zichichi, D. Bartsch, I. Brock, H. Hartmann

Faculty Publications

Differential cross sections for dijet photoproduction and this process in association with a leading neutron, e ++p→e ++jet+jet+X(+n), have been measured with the ZEUS detector at HERA using an integrated luminosity of 40 pb -1. The fraction of dijet events with a leading neutron was studied as a function of different jet and event variables. Single- and double-differential cross sections are presented as a function of the longitudinal fraction of the proton momentum carried by the leading neutron, x L, and of its transverse momentum squared, pT2. The dijet data are compared to inclusive DIS and photoproduction results; they are …

High-Energy Amplitudes In N= 4 Sym In The Next-To-Leading Order, Ian Balitsky, Giovanni A. Chirilli

Physics Faculty Publications

The high-energy behavior of the N = 4 SYM amplitudes in the Regge limit can be calculated order by order in perturbation theory using the high-energy operator expansion in Wilson lines. At large Nc , a typical four-point amplitude is determined by a single BFKL pomeron. The conformal structure of the four-point amplitude is fixed in terms of two functions: pomeron intercept and the coefficient function in front of the pomeron (the product of two residues). The pomeron intercept is universal while the coefficient function depends on the correlator in question. The intercept is known in the first two orders …