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- Baryon resonances (2)
- Nucleon resonances (2)
- Spin-density matrix elements (2)
- AFM (1)
- Big bang cosmology (1)
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- Biomimetic material (1)
- Compound nuclei (1)
- Cosmic microwave background (1)
- Cosmological redshift (1)
- Direct reaction induced fission probability ratio (1)
- Doppler shift (1)
- Dresselhaus spin-orbit (1)
- Electrocouplings (1)
- Electron decay spectroscopy (1)
- Excitation (1)
- Exclusive channels of meson electroproduction off protons (1)
- Factorization property (1)
- Fibrinogen (1)
- Fluorescence (1)
- Gamma ray spectroscopy (1)
- Gluon (1)
- Gluonic-hybrid hadrons (1)
- Hadron (1)
- Hadronic physics (1)
- Hard scattering processes (1)
- Heavy elements (1)
- Hf isotopes (1)
- Interacting boson approximation (IBA) (1)
- Interferometric techniques (1)
- Internal surrogate ratio method (1)
Articles 1 - 20 of 20
Full-Text Articles in Entire DC Network
Partial Wave Analysis Of The Reaction Γp→Pω And The Search For Nucleon Resonances, M. Williams, Gerard P. Gilfoyle, Et. Al.
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.
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 θωc.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.
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
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.
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.
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.
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.
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 < xB < 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, xB, 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
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.
Π+ Photoproduction On The Proton For Photon Energies From 0.725 To 2.875 Gev, M. Dugger, Gerard P. Gilfoyle, Et. Al.
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
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 …
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
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
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 …
Search For The Photoexcitation Of Exotic Mesons In The Π+Π+Π- System, M. Nozar, Gerard P. Gilfoyle, Et. Al.
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.
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 Eγ = 3.0–3.8 GeV and -t = 0.4–1.0 GeV2. 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 Mπ+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
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.
The Mechanical Properties Of Individual, Electrospun Fibrinogen Fibers, Christine C. Helms, Corentin Coulais, Manoj Namboothiry, David L. Carroll, Roy R. Hantgan, Martin Guthold
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
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.
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 …
The Kinematic Origin Of The Cosmological Redshift, Emory F. Bunn, David W. Hogg
The Kinematic Origin Of The Cosmological Redshift, Emory F. Bunn, David W. Hogg
Physics Faculty Publications
A common belief about big-bang cosmology is that the cosmological redshift cannot be properly viewed as a Doppler shift (that is, as evidence for a recession velocity), but must be viewed in terms of the stretching of space. We argue that, contrary to this view, the most natural interpretation of the redshift is as a Doppler shift, or rather as the accumulation of many infinitesimal Doppler shifts. The stretching-of-space interpretation obscures a central idea of relativity, namely that it is always valid to choose a coordinate system that is locally Minkowskian. We show that an observed frequency shift in any …