Digital Commons Network^™

Partial Wave Analysis Of The Reaction Γp→Pω And The Search For Nucleon Resonances, M. Williams, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

An event-based partial wave analysis (PWA) of the reaction γp → pω has been performed on a high-statistics dataset obtained using the CLAS at Jefferson Lab for center-of-mass energies from threshold up to 2.4 GeV. This analysis benefits from access to the world’s first high-precision spin-density matrix element measurements, available to the event-based PWA through the decay distribution of ω → π ⁺π ⁻π⁰. The data confirm the dominance of the t-channel π⁰ exchange amplitude in the forward direction. The dominant resonance contributions are consistent with the previously identified states F₁₅(1680) and …

Differential Cross Sections And Spin Density Matrix Elements For The Reaction Γp→Pω, M. Williams, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

High-statistics differential cross sections and spin-density matrix elements for the reaction γp → pω have been measured using the CEBAF large acceptance spectrometer (CLAS) at Jefferson Lab for center-of-mass (c.m.) energies from threshold up to 2.84 GeV. Results are reported in 112 10-MeV wide c.m. energy bins, each subdivided into cos θ^ω_c.m. bins of width 0.1. These are the most precise and extensive ω photoproduction measurements to date. A number of prominent structures are clearly present in the data. Many of these have not previously been observed due to limited statistics in earlier measurements.

Electroexcitation Of Nucleon Resonances From Clas Data On Single Pion Electroproduction, I. G. Aznauryan, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

We present results on the electroexcitation of the low mass resonances ∆(1232)P₃₃, N(1440)P₁₁, N(1520)D₁₃, and N(1535)S₁₁ in a wide range of Q₂. The results were obtained in the comprehensive analysis of data from the Continuous Electron Beam Accelerator Facility (CEBAF) large acceptance spectrometer (CLAS) detector at the Thomas Jefferson National Accelerator Facility (JLab) on differential cross sections, longitudinally polarized beam asymmetries, and longitudinal target and beam-target asymmetries for π electroproduction off the proton. The data were analyzed using two conceptually different approaches—fixed-t dispersion …

G Factor Of The 2+1 State Of 172Hf, Z. Berant, E. Oster, R. J. Casperson, A. Wolf, V. Werner, A. Heinz, R. F. Casten, G. Gurdal, E. A. Mccutchan, D. S. Brenner, J. R. Terry, R. Winkler, E. Williams, J. Qian, A. Schmidt, M. K. Smith, T. Ahn, C. W. Beausang, P. H. Regan, T. J. Ross, M. Bunce, B. Darakchieva, D. A. Meyer, J. Leblanc, K. Dudziak, C. Bauer, G. Henning

Physics Faculty Publications

The g factor of the 2⁺₁ state of ¹⁷²Hf was measured using the perturbed angular correlation technique in a static external magnetic field. The result, g(2⁺₁) = 0.25(5), is discussed in relation to the systematics of the previously reported g factors in the Hf isotopes and compared with the predictions of several models. An interesting outcome of the analysis presented in this paper is the agreement between the calculated g factors within the interacting boson approximation (IBA) and the results of a large-scale shell model calculation. This agreement supports the emphasis in the …

Differential Cross Sections For The Reactions Γp→Pη And Γp→Pη', M. Williams, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

High-statistics differential cross sections for the reactions γp → pη and γp → pη' have been measured using the CEBAF large acceptance spectrometer (CLAS) at Jefferson Lab for center-of-mass energies from near threshold up to 2.84 GeV. The η' results are the most precise to date and provide the largest energy and angular coverage. The η measurements extend the energy range of the world’s large-angle results by approximately 300 MeV. These new data, in particular the η' measurements, are likely to help constrain the analyses being performed to search for new baryon resonance states.

Photoproduction Of Π​+Π​- Meson Pairs On The Proton, M. Battaglieri, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

The exclusive reaction γp → pπ⁺π^- was studied in the photon energy range 3.0–3.8 GeV and the momentum transfer range 0:4 < -t < 1:0 GeV². Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility. In this kinematic range, the integrated luminosity was about 20 pb^-1. The reaction was isolated by detecting the π⁺ and proton in CLAS, and reconstructing the π^- via the missing-mass technique. Moments of the di-pion decay angular distributions were derived from the experimental data. Differential cross sections for the S, P, and D …

Photodisintegration Of 4He Into P + T, R. Nasseripour, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

The two-body photodisintegration of ⁴He into a proton and a triton has been studied using the CEBAF Large-Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. Real photons produced with the Hall-B bremsstrahlung-tagging system in the energy range from 0.35 to 1.55 GeV were incident on a liquid ⁴He target. This is the first measurement of the photodisintegration of ⁴He above 0.4 GeV. The differential cross sections for the γ ⁴He → pt reaction were measured as a function of photon-beam energy and proton-scattering angle and are compared with the latest model calculations by J.M. …

Beam Spin Asymmetries In Deeply Virtual Compton Scattering (Dvcs) With Clas At 4.8 Gev, G. Gavalian, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

We report measurements of the beam spin asymmetry in deeply virtual Compton scattering (DVCS) at an electron beam energy of 4.8 GeV using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The DVCS beam spin asymmetry has been measured in a wide range of kinematics, 1.0 < Q² < 2.8 (GeV/c)², 0.12 < x_B < 0.48, and 0.1 < −t < 0.8 (GeV/c)², using the reaction ep → e' p X. The number of H(e, e' γ p) and H(e, e'π⁰p) events are separated in each (Q², x_B, t …

High-K Multi-Quasiparticle States And Rotational Bands In 255103Lr., H. B. Jeppesen, R. M. Clark, K. E. Gregorich, A. V. Afanasjev, M. N. Ali, J. M. Allmond, C. W. Beausang, M. Cromaz, M. A. Deleplanque, I. Dragojevic, J. Dvorak, P. A. Ellison, P. Fallon, M. A. Garcia, J. M. Gates, S. Gros, I. Y. Lee, A. O. Macchiavelli, S. L. Nelson, H. Nitsche, L. Stavsetra, F. S. Stephens, M. Wiedeking

Physics Faculty Publications

Two isomeric states have been identified in ²⁵⁵Lr. The decay of the isomers populates rotational structures. Comparison with macroscopic-microscopic calculations suggests that the lowest observed sequence is built upon the [624]9/2⁺ Nilsson state. However, microscopic cranked relativistic Hartree-Bogoliubov (CRHB) calculations do not reproduce the moment of inertia within typical accuracy. This is a clear challenge to theories describing the heaviest elements.

Distance Dependence Of Electron Transfer Kinetics For Azurin Protein Adsorbed To Monolayer Protected Nanoparticle Film Assemblies, Morgan Lynn Vargo, Chris P. Gulka, John K. Gerig, Christopher M. Manieri, Jonathan D. Dattelbaum, Carolyn B. Marks, Nathaniel T. Lawrence, Matthew L. Trawick, Michael C. Leopold

Chemistry Faculty Publications

The distance dependence and kinetics of the heterogeneous electron transfer (ET) reaction for the redox protein azurin adsorbed to an electrode modified with a gold nanoparticle film are investigated using cyclic voltammetry. The nanoparticle films are comprised of nonaqueous nanoparticles, known as monolayer-protected clusters (MPCs), which are covalently networked with dithiol linkers. The MPC film assembly serves as an alternative adsorption platform to the traditional alkanethiolate self-assembled monolayer (SAM) modified electrodes that are commonly employed to study the ET kinetics of immobilized redox proteins, a strategy known as protein monolayer electrochemistry. Voltammetric analysis of the ET kinetics for azurin adsorbed …

Π+ Photoproduction On The Proton For Photon Energies From 0.725 To 2.875 Gev, M. Dugger, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

Differential cross sections for the reaction γp → nπ⁺ have been measured with the CEBAF Large Acceptance Spectrometer (CLAS) and a tagged photon beam with energies from 0.725 to 2.875 GeV. Where available, the results obtained here compare well with previously published results for the reaction. Agreement with the SAID andMAID analyses is found below 1 GeV. The present set of cross sections has been incorporated into the SAID database, and exploratory fits have been made up to 2.7 GeV. Resonance couplings have been extracted and compared to previous determinations. With the addition of these cross sections to the …

Relative 235U(N,Γ) And (N,F) Cross Sections From 235U(D,Pγ) And (D,Pf), J. M. Allmond, L. A. Bernstein, C. W. Beausang, L. Phair, D. L. Bleuel, J. T. Burke, J. Escher, K. E. Evans, B. L. Goldblum, R. Hatarik, H. B. Jeppesen, S. R. Lesher, M. A. Mcmahan, J. O. Rasmussen, N. D. Scielzo, M. Wiedeking

Physics Faculty Publications

The internal surrogate ratio method allows for the determination of an unknown cross section, such as (n,γ), relative to a better-known cross section, such as (n,f), by measuring the relative exit-channel probabilities of a surrogate reaction that proceeds through the same compound nucleus. The validity of the internal surrogate ratio method is tested by comparing the relative γ and fission exit-channel probabilities of a ²³⁶U^∗ compound nucleus, formed in the ²³⁵U(d,p) reaction, to the known ²³⁵U(n,γ) and (n,f) cross sections. A model-independent method for measuring the …

Pairing Software-Managed Caching With Decay Techniques To Balance Reliability And Static Power In Next-Generation Caches, Kelly Shaw, Margaret Martonosi

Department of Math & Statistics Technical Report Series

Since array structures represent well over half the area and transistors on-chip, maintaining their ability to scale is crucial for overall technology scaling. Shrinking transistor sizes are resulting in increased probabilities of single events causing single- and multi-bit upsets which require adoption of more complex and power hungry error detection and correction codes (ECC) in hardware. At the same time, SRAM leakage energy is increasing partly due to technology trends and partly due to the increasing number of transistors present.

This paper proposes and evaluates methods of reducing the static power requirements of caches, while also maintaining high reliability. In …

Surrogate Ratio Method In The Actinide Region Using The (Α,Α'F) Reaction, S. R. Lesher, J. T. Burke, L. A. Bernstein, H. Ai, C. W. Beausang, D. L. Bleuel, R. M. Clark, F. S. Dietrich, J. Escher, P. Fallon, J. Gibelin, B. L. Goldblum, I. Y. Lee, A. O. Macchiavelli, M. A. Mcmahan, K. Moody, E. B. Norman, L. Phair, E. Rodriguez-Vieitez, N. D. Scielzo, M. Wiedeking

Physics Faculty Publications

In the Surrogate Method, the measured decay probability of a compound nucleus formed via a direct reaction is used to extract the cross section for a reaction with a different entrance channel that proceeds through the same compound nucleus. An extension of the Surrogate Method, the Surrogate Ratio Method (SRM), uses a ratio of measured decay probabilities to infer an unknown cross section relative to a known one. To test the SRM we compare the direct-reaction-induced fission probability ratio of ²³⁴U(α, α’ f ) to ²³⁶U(α, α’f ) with the ratio of cross sections …

Spin-Polarization In Quantum Wires: Influence Of Dresselhaus Spin-Orbit Interaction And Cross-Section Effects, L. Villegas-Lelovsky, C. Trallero-Giner, Mariama Rebello Sousa Dias, V. Lopez-Richard, G. E. Marques

Physics Faculty Publications

We examine the effects of the full Dresselhaus spin-orbit coupling on laterally confined quantum wire states. An analysis of the relative contributions due to linear, quadratic, and cubic Dresselhaus spin-orbit terms on the energy levels, spin splitting, and spin polarization has been carried out. The effects of wire cross-sectional geometry shapes on the electronic structure are explored. In particular we compared the results of semicylindrical and cylindrical confinements and have found important differences between the spin degeneracy of the ground-state level and the spin-polarization dependence on sign inversion of the free linear momentum quantum number along the wire axis. Different …

Optical Properties Of Multilayer-Polyelectrolyte Films With Incorporated Gold Nanomaterials (Solid Nanoparticles And Hollow Nanoshells), Robert Watson Day

Honors Theses

The growth of various multilayer‐polymer multilayer‐nanoparticle films was successfully achieved. Multilayer‐polymer multilayer‐nanoparticle films with 1, 3, and 5 polymer layers between nanoparticle layers exhibit significantly different optical properties due to the differences in magnitude of particle plasmon coupling. These film systems were also successfully extended to hollow gold nanoshells, which have significantly enhanced optical properties in comparison to solid gold nanoparticles of similar sizes. A proposal for utilizing this increased sensitivity of the gold nanoshells to explore the ‘microenvironments’ for optimizing potential sensing applications is also presented.

Polyelectrolyte-Linked Film Assemblies Of Nanoparticles And Nanoshells: Growth, Stability, And Optical Properties, Anne A. Galyean, Justin Malinowski, Robert W. Day, Kevin W. Kittredge, Michael C. Leopold

Chemistry Faculty Publications

Multi-layer films of nanoparticles and nanoshells featuring various polymeric linkage molecules have been assembled and their optical properties characterized. The growth dynamics, including molecular weight effects, and stability of the various nanoparticle film constructions, using both single polymer as well as combinations of alternating charge polyelectrolytes as linking mechanisms, are presented. The polymeric linkers studied include poly-L-lysine, poly-L-arginine, poly(allylamine hydrochloride), and polyamidoamine dendrimers. Significantly air stable films were achieved with the use of multi-layered polymeric bridges between the nanoparticles and nanoshells. Optical sensitivity normally observed with these nanomaterials in solution was observed for their corresponding film geometries, with the nanoshell …

Search For The Photoexcitation Of Exotic Mesons In The Π​+Π​+Π- System, M. Nozar, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

A search for exotic mesons in the π⁺π⁺π^- system photoproduced by the charge exchange reaction γp → π⁺π⁺π^- was carried out by the CLAS Collaboration at Jefferson Lab. A tagged-photon beam with energies in the 4.8 to 5.4 GeV range, produced through bremsstrahlung from a 5.744 GeV electron beam, was incident on a liquid-hydrogen target. A partial wave analysis was performed on a sample of 83 000 events, the highest such statistics to date in this reaction at these energies. The main objective of this study was to look …

Measurement Of Direct Ƒ0(980) Photoproduction On The Proton, M. Battaglieri, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

We report on the results of the first measurement of exclusive ƒ₀(980) meson photoproduction on protons for E_γ = 3.0–3.8 GeV and -t = 0.4–1.0 GeV^2. Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility. The resonance was detected via its decay in the π⁺ π^- channel by performing a partial wave analysis of the reaction γ p → pπ⁺π^-. Clear evidence of the ƒ₀(980) meson was found in the interference between P and S waves at M_{π⁺π …}

Multi-Quasiparticle States In 256Rf, H. B. Jeppesen, I. Dragojevic, R. M. Clark, K. E. Gregorich, M. N. Ali, J. M. Allmond, C. W. Beausang, D. L. Bleuel, M. Cromaz, M. A. Deleplanque, P. A. Ellison, P. Fallon, M. A. Garcia, J. M. Gates, J. P. Greene, S. Gros, I. Y. Lee, H. L. Liu, A. O. Macchiavelli, S. L. Nelson, H. Nitsche, J. R. Pavan, L. Stavsetra, F. S. Stephens, M. Wiedeking, R. Wyss, F. R. Xu

Physics Faculty Publications

Excited states in ²⁵⁶Rf were populated via the ²⁰⁸Pb(⁵⁰Ti,2n) fusion–evaporation reaction. Delayed γ-ray and electron decay spectroscopy was performed and three isomeric states in ²⁵⁶Rf have been identified. A fourth low-energy nonyrast state was identified from the γ-ray decay of one of the higher lying isomers. The states are interpreted as multi-quasiparticle excitations.

Trimethylsilyl Trifluoromethanesulfonate- Accelerated Addition Of Catalytically Generated Zinc Acetylides To Aldehydes, C. Wade Downey, Brian D. Mahoney, Vincent R. Lipari

Chemistry Faculty Publications

In the presence of TMSOTf, a wide variety of terminal acetylenes add rapidly and efficiently to aldehydes via a catalytically generated zinc acetylide. In the absence of TMSOTf, no reaction is observed under otherwise identical conditions.

The Mechanical Properties Of Individual, Electrospun Fibrinogen Fibers, Christine C. Helms, Corentin Coulais, Manoj Namboothiry, David L. Carroll, Roy R. Hantgan, Martin Guthold

Physics Faculty Publications

We used a combined atomic force microscope (AFM)/fluorescence microscope technique to study the mechanical properties of individual, electrospun fibrinogen fibers in aqueous buffer. Fibers (average diameter 208 nm) were suspended over 12 μm-wide grooves in a striated, transparent substrate. The AFM, situated above the sample, was used to laterally stretch the fibers and to measure the applied force. The fluorescence microscope, situated below the sample, was used to visualize the stretching process. The fibers could be stretched to 2.3 times their original length before breaking; the breaking stress was 22·10⁶ Pa. We collected incremental stress-strain curves to determine the …

Phase Shift Sequences For An Adding Interferometer, Peter Hyland, Brent Follin, Emory F. Bunn

Physics Faculty Publications

Cosmic microwave background (CMB) polarimetry has the potential to provide revolutionary advances in cosmology. Future experiments to detect the very weak B-mode signal in CMB polarization maps will require unprecedented sensitivity and control of systematic errors. Bolometric interferometry may provide a way to achieve these goals. In a bolometric interferometer (or other adding interferometer), phase shift sequences are applied to the inputs in order to recover the visibilities. Noise is minimized when the phase shift sequences corresponding to all visibilities are orthogonal. We present a systematic method for finding sequences that produce this orthogonality, approximately minimizing both the length of …

Electroproduction Of Pπ+​Π- Off Protons At 0.2 < Q2 < 0.6 Gev2 And 1.3 < W < 1.57 Gev With The Clas Detector, G. V. Fedotov, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

This paper reports on the most comprehensive data set obtained on differential and fully integrated cross sections for the process ep → e'pπ⁺π ⁻. The data were collected with the CLAS detector at Jefferson Laboratory. Measurements were carried out in the as yet unexplored kinematic region of photon virtuality 0.2 < Q² < 0.6 GeV² and invariant mass of the final hadron system W from 1.3 to 1.57 GeV. For the first time, nine independent one-fold differential cross sections were determined in each bin of W and Q² covered by the measurements. A phenomenological analysis of the data …

Common Cyclic Vectors For Unitary Operators, William T. Ross, Warren R. Wogen

Department of Math & Statistics Faculty Publications

In this paper, we determine whether or not certain natural classes of unitary multiplication operators on L²(dƟ) have common cyclic vectors. For some classes which have common cyclic vectors, we obtain a classification of these vectors.

A Nonlinear Extremal Problem On The Hardy Space, William T. Ross, Stephan Ramon Garcia

Department of Math & Statistics Faculty Publications

We relate some classical extremal problems on the Hardy space to norms of truncated Toeplitz operators and complex symmetric operators

Complementary Responses To Mean And Variance Modulations In The Perfect Integrate-And-Fire Model, Joanna R. Wares, Todd W. Troyer

Department of Math & Statistics Faculty Publications

In the perfect integrate-and-fire model (PIF), the membrane voltage is proportional to the integral of the input current since the time of the previous spike. It has been shown that the firing rate within a noise free ensemble of PIF neurons responds instantaneously to dynamic changes in the input current, whereas in the presence of white noise, model neurons preferentially pass low frequency modulations of the mean current. Here, we prove that when the input variance is perturbed while holding the mean current constant, the PIF responds preferentially to high frequency modulations. Moreover, the linear filters for mean and variance …

Biology In Mathematics At The University Of Richmond, Lester Caudill

Department of Math & Statistics Faculty Publications

In an effort to meet the needs of science students for modeling skills, three new courses have been created at the University of Richmond: Scientific Calculus I and II, and Mathematical Models in Biology and Medicine. The courses are described, and lessons learned and future directions are discussed.

Extending The Skill Test For Disease Diagnosis, Shu-Chuan Lin, Paul H. Kvam, Jye-Chyi Lu

Department of Math & Statistics Faculty Publications

For diagnostic tests, we present an extension to the skill plot introduced by Briggs and Zaretski (Biometrics 2008; 64:250–261). The method is motivated by diagnostic measures for osteopetrosis in a study summarized by Hans et al. (The Lancet 1996; 348:511–514). Diagnostic test accuracy is typically defined using the area (or partial area) under the receiver operator characteristic (ROC) curve. If partial area is used, the resulting statistic can be highly subjective because the focus region of the ROC curve corresponds to a set of low false‐positive rates that are chosen by the experimenter. This paper introduces a more …

[Introduction To] The Hardy Space Of A Slit Domain, William T. Ross, Alexandra Aleman, Nathan S. Feldman

Bookshelf

If H is a Hilbert space and T : H ? H is a continous linear operator, a natural question to ask is: What are the closed subspaces M of H for which T M ? M? Of course the famous invariant subspace problem asks whether or not T has any non-trivial invariant subspaces. This monograph is part of a long line of study of the invariant subspaces of the operator T = M (multiplication by the independent variable z, i. e. , M f = zf ) on a z z Hilbert space of analytic functions on a bounded …