Digital Commons Network^™

Remnants Of Spherical Shell Structures In Deformed Nuclei: The Impact Of An N = 64 Neutron Subshell Closure On The Structure Of N ≈ 90 Gadolinium Nuclei, T. J. Ross, R. O. Hughes, C. W. Beausang, J. M. Allmond, C. Angell, M. S. Basunia, D. L. Bleuel, J. T. Burke, R. J. Casperson, J. Escher, P. Fallon, R. Hatarik, J. Munson, S. Paschalis, M. Petri, L. Phair, J. J. Ressler, N. D. Scielzo

Physics Faculty Publications

Odd-mass gadolinium isotopes around N = 90 were populated by the (p,d) reaction, utilizing 25-MeV protons, resulting in population of low-spin quasineutron states at energies near and below the Fermi surface. Systematics of the single quasineutron levels populated are presented. A large excitation energy gap is observed between levels originating from the 2d_3/2, 1h_11/2, and 3s_1/2 spherical parents (above the N = 64 gap), and the 2d_5/2 (below the gap), indicating that the spherical shell model level spacing is maintained at least to moderate deformations.

Quadrupole Collectivity In Neutron-Rich Fe And Cr Isotopes, H. L. Crawford, R. M. Clark, P. Fallon, A. O. Macchiavelli, T. Baugher, D. Bazin, C. W. Beausang, J. S. Berryman, D. L. Bleuel, C. M. Campbell, M. Cromaz, G. De Angelis, A. Gade, R. O. Hughes, I. Y. Lee, S. M. Lenzi, F. Nowacki, S. Paschalis, M. Petri, A. Poves, A. Ratkiewicz, T. J. Ross, E. Sahin, D. Weisshaar, K. Wimmer, R. Winkler

Physics Faculty Publications

Intermediate-energy Coulomb excitation measurements are performed on the N≥40 neutron-rich nuclei ^{66, 68}Fe and ⁶⁴Cr. The reduced transition matrix elements providing a direct measure of the quadrupole collectivity B(E2; 2⁺₁→ 0⁺₁) are determined for the first time in ⁶⁸Fe₄₂ and ⁶⁴Cr₄₀ and confirm a previous recoil distance method lifetime measurement in ⁶⁶Fe₄₀. The results are compared to state-of-the-art large-scale shell-model calculations within the full fpgd neutron orbital model space using the Lenzi-Nowacki-Poves-Sieja effective interaction and confirm the results of the calculations that show …

High-Spin Study Of The Shell Model Nucleus 88Y49, M. Bunce, P. H. Regan, V. Werner, C. W. Beausang, A. Anagnostatou, M. Bowry, R. J. Casperson, D. Chen, N. Cooper, P. Goddard, R. O. Hughes, G. Ilie, P.J.R. Mason, B. Pauerstein, M. W. Reed, T. J. Ross, E. C. Simpson

Physics Faculty Publications

The near-yrast structure of the near-magic, odd-odd nucleus, ⁸⁸₃₉Y₄₉, has been studied into the high-spin regime. Investigations were performed at the Wright Nuclear Structure Laboratory, Yale University, using the ⁷⁴Ge(¹⁸O,p3n) and ⁷⁶Ge(¹⁸O,p5n) fusion-evaporation reactions at beam energies of 60 and 90 MeV, respectively. Gamma-ray energy coincidence analyses using both double (γ²) and triple (γ³) fold coincidences, together with angular correlation measurements, have been used to extend the previously reported level scheme to an excitation energy of 8.6 MeV and a …

Near-Threshold Neutral Pion Electroproduction At High Momentum Transfers And Generalized Form Factors, P. Khetarpal, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

We report the measurement of near-threshold neutral pion electroproduction cross sections and the extraction of the associated structure functions on the proton in the kinematic range Q² from 2 to 4.5 GeV² and W from 1.08 to 1.16 GeV. These measurements allow us to access the dominant pion-nucleon s-wave multipoles E₀₊ and S₀₊ in the near-threshold region. In the light-cone sum-rule framework (LCSR), these multipoles are related to the generalized form factors G₁^π0p (Q²) and G₂^π0p (Q²). The data are compared to these …

Spectroscopy Of 88Y By The (P,Dγ) Reaction, T. J. Ross, C. W. Beausang, R. O. Hughes, N. D. Scielzo, J. T. Burke, J. M. Allmond, C. Angell, M. S. Basunia, D. L. Bleuel, R. J. Casperson, J. Escher, P. Fallon, R. Hatarik, J. Munson, S. Paschalis, M. Petri, L. Phair, J. J. Ressler

Physics Faculty Publications

Low-spin, high-excitation energy states in ⁸⁸Y have been studied using the ⁸⁹Y(p,dγ) reaction. For this experiment a 25 MeV proton beam was incident upon a monoisotopic ⁸⁹Y target. A silicon telescope array was used to detect deuterons, and coincident γ rays were detected using a germanium clover array. Most of the known low-excitation-energy low-spin states populated strongly via the (p,d) reaction mechanism are confirmed. Two states are seen for the first time and seven new transitions, including one which bypasses the two low-lying isomeric states, are observed.

Triaxial Deformation And Nuclear Shape Transition In 192Au, Y. Oktem, D. L. Balabanski, B. Akkus, L. Amon Susam, L. Atanasova, C. W. Beausang, R. Cakirli, R. F. Casten, M. Danchev, M. Djongolov, E. Ganioglu, K. A. Gladnishki, J. Tm. Goon, D. J. Hartley, A. A. Hecht, R. Krucken, J. R. Novak, G. Rainovski, L. L. Riedinger, T. Venkova, I. Yigitoglu, N. V. Zamfir, O. Zeidan

Physics Faculty Publications

Background: Nuclei in the A≈190 mass region show gradual shape changes from prolate through nonaxial deformed shapes and ultimately towards spherical shapes as the Pb region is approached. Exploring how this shape evolution occurs will help us understand the evolution of collectivity in this region.

Purpose: The level scheme of the ¹⁹²Au nucleus in A ≈ 190 region was studied in order to deduce its deformations.

Methods: High-spin states of ¹⁹²Au have been populated in the ¹⁸⁶W(¹¹B, 5n) reaction at a beam energy of 68 MeV and their γ decay was studied …

Experimental Study Of The P11(1440) And D13(1520) Resonances From The Clas Data On Ep→E′Π+Π−P′, V. I. Mokeev, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

The transition helicity amplitudes from the proton ground state to the P₁₁(1440) and D₁₃(1520) excited states (v_γpN* electrocouplings) were determined from the analysis of nine independent one-fold differential π⁺π⁻p electroproduction cross sections off a proton target, taken with CLAS at photon virtualities of 0.25 < Q² < 0.60 GeV². The phenomenological reaction model was employed for separation of the resonant and nonresonant contributions to the final state. The P₁₁(1440) and D₁₃(1520) electrocouplings were obtained from the resonant amplitudes parametrized within the framework of a unitarized …

Comparison Of Forward And Backward Pp Pair Knockout In 3He(E,E′Pp)N, H. Baghdasaryan, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

Measuring nucleon-nucleon short range correlations (SRCs) has been a goal of the nuclear physics community for many years. They are an important part of the nuclear wave function, accounting for almost all of the high-momentum strength. They are closely related to the EMC effect. While their overall probability has been measured, measuring their momentum distributions is more difficult. In order to determine the best configuration for studying SRC momentum distributions, we measured the ³He(e,e’ pp)n reaction, looking at events with high-momentum protons (p_p > 0.35 GeV/c) and a low-momentum neutron ( …

Measurement Of The Entry-Spin Distribution Imparted To The High Excitation Continuum Region Of Gadolinium Nuclei Via (P,D) And (P,T) Reactions, T. J. Ross, C. W. Beausang, R. O. Hughes, J. M. Allmond, C. Angell, M. S. Basunia, D. L. Bleuel, J. T. Burke, R. J. Casperson, J. Escher, P. Fallon, R. Hatarik, J. Munson, S. Paschalis, M. Petri, L. Phair, J. J. Ressler, N. D. Scielzo, I. Thompson

Physics Faculty Publications

Over the last several years, the surrogate reaction technique has been successfully employed to extract (n,f) and (n,γ) cross sections in the actinide region to a precision of ∼5% and ∼20%, respectively. However, attempts to apply the technique in the rare earth region have shown large (factors of 2–3) discrepancies between the directly measured (n,γ) and extracted surrogate cross sections. One possible origin of this discrepancy lies in differences between the initial spin-parity population distribution in the neutron induced and surrogate reactions. To address this issue, the angular …

Statistical Γ Rays In The Analysis Of Surrogate Nuclear Reactions, N. D. Scielzo, J. Escher, J. M. Allmond, M. S. Basunia, C. W. Beausang, L. A. Bernstein, D. L. Bleuel, J. T. Burke, R. M. Clark, F. S. Dietrich, P. Fallon, J. Gibelin, B. L. Goldblum, S. R. Lesher, M. A. Mcmahan, E. B. Norman, L. Phair, E. Rodriguez-Vieitez, S. A. Sheets, I. Thompson, M. Wiedeking

Physics Faculty Publications

The surrogate nuclear reaction method is being applied in many efforts to indirectly determine neutron-induced reaction cross sections on short-lived isotopes. This technique aims to extract accurate (n,γ) cross sections from measured decay properties of the compound nucleus of interest (created using a different reaction). The advantages and limitations of a method that identifies the γ-ray decay channel by detecting any high-energy (“statistical”) γ ray emitted during the relaxation of the compound nucleus were investigated. Data collected using the Silicon Telescope Array for Reaction Studies and Livermore-Berkeley Array for Collaborative Experiments silicon and germanium detector arrays were used …

Measurement Of The Neutron F2 Structure Function Via Spectator Tagging With Clas, N. Baillie, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

We report on the first measurement of the F₂ structure function of the neutron from semi-inclusive scattering of electrons from deuterium, with low-momentum protons detected in the backward hemisphere. Restricting the momentum of the spectator protons to ≲ 100° MeV/c and their angles to ≳ 100° relative to the momentum transfer allows an interpretation of the process in terms of scattering from nearly on-shell neutrons. The Fⁿ₂ data collected cover the nucleon-resonance and deep-inelastic regions over a wide range of Bjorken x for 0.65 < Q² < 4.52 GeV², with uncertainties from nuclear corrections estimated to be less than …

Measurement Of The Generalized Form Factors Near Threshold Via Γ*P→Nπ+ At High Q2, K. Park, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

We report the first extraction of the pion-nucleon multipoles near the production threshold for the nπ⁺ channel at relatively high momentum transfer (Q² up to 4.2 GeV²). The dominance of the s-wave transverse multipole (E₀₊), expected in this region, allowed us to access the generalized form factor G₁ within the light-cone sum-rule (LCSR) framework as well as the axial form factor G_A. The data analyzed in this work were collected by the nearly 4π CEBAF Large Acceptance Spectrometer (CLAS) using a 5.754-GeV electron beam on a proton …

Utilizing (P,D) And (P,T) Reactions To Obtain (N,F) Cross Sections In Uranium Nuclei Via The Surrogate-Ratio Method, R. O. Hughes, C. W. Beausang, T. J. Ross, J. T. Burke, N. D. Scielzo, M. S. Basunia, C. M. Campbell, R. J. Casperson, H. L. Crawford, J. Escher, J. Munson, L. Phair, J. J. Ressler

Physics Faculty Publications

The surrogate ratio method has been tested for (p,d) and (p,t) reactions on uranium nuclei. ²³⁶U and ²³⁸U targets were bombarded with 28-MeV protons and the light ion recoils and fission fragments were detected using the Silicon Telescope Array for Reaction Studies detector array at the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory. The (p,df) reaction channels on ²³⁶U and ²³⁸U targets were used as a surrogate to determine the σ[²³⁶U(n,f)]/σ[²³⁴U(n, …

Upper Limits For The Photoproduction Cross Section For The Φ−−(1860) Pentaquark State Off The Deuteron, H. Egiyan, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

We searched for the Φ^--(1860) pentaquark in the photoproduction process off the deuteron in the Ξ^-π^--decay channel using CLAS. The invariant-mass spectrum of the Ξ^-π^- system does not indicate any statistically significant enhancement near the reported mass M = 1.860 GeV. The statistical analysis of the sideband-subtracted mass spectrum yields a 90%-confidence-level upper limit of 0.7 nb for the photoproduction cross section of Φ^--(1860) with a consecutive decay into Ξ^-π^- in the photon-energy range 4.5 GeV < E_γ < 5.5 GeV.

To The Continuum And Beyond: Structure Of U Nuclei, R. O. Hughes, C. W. Beausang, T. J. Ross, J. T. Burke, N. D. Scielzo, M. S. Basunia, C. M. Campbell, R. J. Casperson, H. L. Crawford, J. Munson, L. Phair, J. J. Ressler

Physics Faculty Publications

An experiment was performed at the 88-inch cyclotron at LBNL to investigate the structure of uranium isotopes and concurrently test the so-called surrogate ratio method. A 28 MeV proton beam was used to bombard ²³⁶U and ²³⁸U targets and the outgoing light ions were detected using the STARS silicon telescope allowing isotopic assignments and the excitation energy of the compound nucleus to be measured. A fission detector was placed at backward angles to give particle-fission coincidences, while the six clover germanium detectors of the LIBERACE array were used for particle-γ coincidences. The (p,d) reaction channels on ²³⁶U …

A Shell Model Study Of The High Spin States Of 88Y, M. Bunce, P. H. Regan, V. Werner, A. Anagnostatou, C. W. Beausang, M. Bowry, R. J. Casperson, D. Chen, N. Cooper, P. Goddard, R. O. Hughes, G. Ilie, P.J.R. Mason, B. Pauerstein, M. W. Reed

Physics Faculty Publications

Experiments were carried out at the Wright Nuclear Structure Laboratory at Yale University using the 21MV ESTU Tandem Van de Graaff accelerator with the purpose of studying ⁸⁸Y. A beam of ¹⁸O impinged at laboratory energies of 60, 65 and 70 MeV on a 600 μg/cm ^{2 74}Ge target with a thick (10mg/cm ²) ¹⁹⁷Au backing. This experiment was performed with the specific aim of accessing medium spin states of the nucleus of interest. A second experiment was undertaken to populate the nucleus of interest in higher spin states by impinging the same ^{18 …}

Comment On “Observation Of A Narrow Structure In 1H(Γ,KS0)X Via Interference With Φ-Meson Production”, M. Anghinolfi, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

In Ref. [1], the authors claim to observe a narrow structure in the mass spectrum constructed from the (pKL) system using data from the CLAS detector. The interpretation of this narrow structure given in Ref. [1] is as follows: “It may be due to the photoproduction of the Θ⁺pentaquark or some unknown Σ* resonance.” The authors go on to say that “it is unlikely for the observed structure to be due to a Σ* resonance.”

Surrogate Measurement Of The 238Pu(N,F) Cross Section, J. J. Ressler, J. T. Burke, J. Escher, C. Angell, M. S. Basunia, C. W. Beausang, L. A. Bernstein, D. L. Bleuel, R. J. Casperson, B. L. Goldblum, J. Gostic, R. Hatarik, R. Henderson, R. O. Hughes, J. Munson, L. Phair, T. J. Ross, N. D. Scielzo, E. Swanberg, I. Thompson, M. Wiedeking

Physics Faculty Publications

The neutron-induced fission cross section of ²³⁸Pu was determined using the surrogate ratio method. The (n,f) cross section over an equivalent neutron energy range 5–20 MeV was deduced from inelastic α-induced fission reactions on ²³⁹Pu, with ²³⁵U(α,α′f) and ²³⁶U(α,α′f) used as references. These reference reactions reflect ²³⁴U(n,f) and ²³⁵U(n,f) yields, respectively. The deduced ²³⁸Pu(n,f) cross section agrees well with standard data libraries up to …

Coherent Photoproduction Of Π+ From 3he, R. Nasseripour, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

We have measured the differential cross section for the γ³He→ π⁺t reaction. This reaction was studied using the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Real photons produced with the Hall-B bremsstrahlung tagging system in the energy range from 0.50 to 1.55 GeV were incident on a cryogenic liquid ³He target. The differential cross sections for the γ³He→ π⁺t reaction were measured as a function of photon-beam energy and pion-scattering angle. Theoretical predictions to date cannot explain the large cross sections except at backward angles, …

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 …

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 …

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 …

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, …

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, …}

Differential Cross Section And Recoil Polarization Measurements For The Γp→K+Λ Reaction Using Clas At Jefferson Lab, M. E. Mccracken, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

We present measurements of the differential cross section and 'B; recoil polarization for the γp → K⁺Λ reaction made using the CLAS detector at Jefferson Lab. These measurements cover the center-of-mass energy range from 1.62 to 2.84 GeV and a wide range of center-of-mass K⁺ production angles. Independent analyses were performed using the K⁺pπ⁻ and K⁺p (missing π⁻) final-state topologies; results from these analyses were found to exhibit good agreement. These differential-cross-section measurements show excellent agreement with previous CLAS and LEPS results and offer increased precision and a 300-MeV increase …

Fission Fragment Isomers Populated Via 6Li+232Th., J. J. Ressler, J. A. Caggiano, C. J. Francy, P. N. Peplowski, J. M. Allmond, C. W. Beausang, L. A. Bernstein, D. L. Bleuel, J. T. Burke, P. Fallon, A. A. Hecht, D. V. Jordan, S. R. Lesher, M. A. Mcmahan, T. S. Palmer, L. Phair, N. D. Scielzo, P. G. Swearingen, G. A. Warren, M. Wiedeking

Physics Faculty Publications

Short-lived isomers in fission fragments following bombardment of 45-MeV ⁶Li on ²³²Th were examined. Isomers in the A ~ 95,122, and 132 mass regions were observed. New isomeric decays were observed in ¹²¹In [T_1/2=17(2) μs], ¹²³In (T_1/2≳100 μs), and ¹²⁵Sb [T_1/2=25(4) μs]. These isomers are suggested to arise from ν(h_11/2⊗d_3/2)7⁻and ν(h_11/2⊗s_1/2)5⁻ neutron core excitations coupling with the valence proton.

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.