Physical Sciences and Mathematics Commons^™

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 …

Inclusive-Jet Photoproduction At Hera And Determination Of Α S, H. Abramowicz, I. Abt, L. Adamczyk, M. Adamus, R. Aggarwal, S. Antonelli, P. Antonioli, A. Antonov, M. Arneodo, V. Aushev, Y. Aushev, O. Bachynska, A. Bamberger, A. N. Barakbaev, G. Barbagli, G. Bari, F. Barreiro, N. Bartosik, D. Bartsch, M. Basile, O. Behnke, J. Behr, U. Behrens, L. Bellagamba, A. Bertolin, S. Bhadra, M. Bindi, C. Blohm, V. Bokhonov, T. Bołd, K. Bondarenko

Faculty Publications

Inclusive-jet cross sections have been measured in the reaction ep→e+jet+X for photon virtuality Q 2γp centre-of-mass energies in the region 142γp-1. Jets were identified using the k T, anti-k T or SIScone jet algorithms in the laboratory frame. Single-differential cross sections are presented as functions of the jet transverse energy, ETjet, and pseudorapidity, jet, for jets with ETjet>17 GeV and -1< jet

Characterization Of Heavy Ion Beams At The Heavy Ion Medical Accelerator In Chiba Using A Li-Drifted 5-Mm Silicon Detector, Alexander Lang

Nuclear Engineering Reports

Measurements were taken at the Heavy Ion Medical Accelerator in Chiba, Japan (HIMAC) to characterize accelerator beams to assist in the study of various tissue equivalent proportional counters (TEPCs) designed by Colorado State University (CSU), Oklahoma State University (OSU), and the National Aeronautics and Space Administration (NASA). There were four beams that were part of the HIMAC experiment:

• 290 MeV/nucleon carbon
• 150 MeV/nucleon helium
• 500 MeV/nucleon argon
• 500 MeV/nucleon iron

For the first time ever, a single, 5-mm lithium drifted silicon detector was used to characterize the beam and measure the spectrum of particles striking the TEPCs. If successful, this …

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 …

Search For A T-Odd, P-Even Triple Correlation In Neutron Decay, T. E. Chupp, R. L. Cooper, K. P. Coulter, S. J. Freedman, B. K. Fujikawa, A. Garcia, Gordon L. Jones, H. P. Mumm, J. S. Nico, A. K. Thompson, C. A. Trull, F. E. Wietfeldt, J. F. Wilkerson

Articles

Background: Time-reversal-invariance violation, or equivalently CP violation, may explain the observed cosmological baryon asymmetry as well as indicate physics beyond the Standard Model. In the decay of polarized neutrons, the triple correlation D⟨⃗Jn⟩/Jn⋅(⃗βe׈pν) is a parity-even, time-reversal-odd observable that is uniquely sensitive to the relative phase of the axial-vector amplitude with respect to the vector amplitude. The triple correlation is also sensitive to possible contributions from scalar and tensor amplitudes. Final-state effects contribute to D at the level of 10−5 and can be calculated with a precision of 1% or better.

Purpose: We have improved the sensitivity to T-odd, P-even …

Hrc Enews — 2012 Summer, Megan M. Iudice

Publications (HRC)

This issue contains staff accomplishments and announcements, event listings, and a "new faces" listing for new staff, affiliates, and researchers.

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 …

Hrc Enews — 2012 Spring, Megan M. Iudice

Publications (HRC)

This issue contains staff accomplishments and announcements, event listings, and a "new faces" listing for new staff, affiliates, and researchers.

Measurement Of The Neutron F2 Structure Function Via Spectator Tagging With Clas, N. Baillie, S. Tkachenko, J. Zhang, P. Bosted, S. Bültmann, M. E. Christy, H. Fenker, K. A. Griffioen, C. E. Keppel, S. E. Kuhn, K. P. Adhikari, D. Adikaram, M. J. Amaryan, H. Baghdasaryan, G. Dodge, N. Guler, C. E. Hyde, A. Klein, A. Klimenko, L. B. Weinstein

Physics Faculty Publications

We report on the first measurement of the F₂ structure function of the neutron from the semi-inclusive scattering of electrons from deuterium, with low-momentum protons detected in the backward hemisphere. Restricting the momentum of the spectator protons to ≲ 100MeV/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 …

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.

Boost-Invariant (2+1)-Dimensional Anisotropic Hydrodynamics, Mauricio Martinez, Radoslaw Ryblewski, Michael T. Strickland

Physics and Astronomy Faculty Publications

We present results of the application of the anisotropic hydrodynamics (aHydro) framework to (2+1)-dimensional boost-invariant systems. The necessary aHydro dynamical equations are derived by taking moments of the Boltzmann equation using a momentum-space anisotropic one-particle distribution function. We present a derivation of the necessary equations and then proceed to numerical solutions of the resulting partial differential equations using both realistic smooth Glauber initial conditions and fluctuating Monte Carlo Glauber initial conditions. For this purpose we have developed two numerical implementations: one that is based on straightforward integration of the resulting partial differential equations supplemented by a two-dimensional weighted Lax-Friedrichs smoothing …

Assessing The Feasibility Of Cosmic-Ray Acceleration By Magnetic Turbulence At The Magnetic Center, M. Fatuzzo, F. Melia

Faculty Scholarship

No abstract provided.

Quantitative Study Of Spin-Flip Co-Tunneling Transport In A Quantum Dot, S. Herbert, T-M. Liu, A. N. Ngo

Faculty Scholarship

No abstract provided.

Hrc Enews — 2012 Winter, Megan M. Iudice

Publications (HRC)

This issue contains staff accomplishments and announcements, event listings, and a "new faces" listing for new staff, affiliates, and researchers.

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.”

Evidence For The Onset Of Color Transparency In Ρ0 Electroproduction Off Nuclei, L. El Fassi, L. Zana, H. Hafidi, M. Holtrop, B. Mustapha, W. K. Brooks, H. Hakobyan, Z. Zheng, K. P. Adhikari, D. Adikaram, M. J. Amaryan, H. Baghdasaryan, S. Bültmann, G. E. Dodge, C. E. Hyde, A. Klein, S. E. Kuhn, M. Mayer, H. Seraydaryan, L. B. Weinstein

Physics Faculty Publications

We have measured the nuclear transparency of the incoherent diffractive A( e , e ′ ρ⁰ ) process in ¹²C and ⁵⁶Fe targets relative to ²H using a 5 GeV electron beam. The nuclear transparency, the ratio of the produced ρ⁰ ʼs on a nucleus relative to deuterium, which is sensitive to ρA interaction, was studied as function of the coherence length (lc), a lifetime of the hadronic fluctuation of the virtual photon, and the four-momentum transfer squared (Q²). While the transparency for both ¹²C and ⁵⁶Fe …

Directed And Elliptic Flow Of Charged Particles In Cu + Cu Collisions At √ˢᶰᶰ =22.4 Gev, G. Agakishiev, M. M. Aggarwal, S. Bueltmann, I. Koralt, X. Zhu, Star Collaboration

Physics Faculty Publications

This paper reports results for directed flow v₁ and elliptic flow v₂ of charged particles in Cu + Cu collisions at √ˢᶰᶰ = 22.4 GeV at the Relativistic Heavy Ion Collider. The measurements are for the 0-60% most central collisions, using charged particles observed in the STAR detector. Our measurements extend to 22.4-GeV Cu + Cu collisions the prior observation that v₁ is independent of the system size at 62.4 and 200 GeV and also extend the scaling of v₁ with η/y_beam to this system. The measured v₂p_T in Cu + Cu …

Ρ0 Photoproduction In Auau Collisions At √ Snn = 62.4 Gev Measured With The Star Detector, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, A. V. Alakhverdyants, I. Alekseev, J. Alford, B. D. Anderson, C. D. Anson, D. Arkhipkin, S. Bueltmann, I. Koralt, D. Plyku

Physics Faculty Publications

Vector mesons may be photoproduced in relativistic heavy-ion collisions when a virtual photon emitted by one nucleus scatters from the other nucleus, emerging as a vector meson. The STAR Collaboration has previously presented measurements of coherent ρ⁰ photoproduction at center of mass energies of 130 GeV and 200 GeV in AuAu collisions. Here, we present a measurement of the cross section at 62.4 GeV; we find that the cross section for coherent ρ0 photoproduction with nuclear breakup is 10.5 ± 1.5 ± 1.6mb at 62.4 GeV. The cross-section ratio between 200 GeV and 62.4 GeV is 4.4 ± 0.6, …

Observation Of A Narrow Structure In 1H(Ykso)X Via Interference With Φ-Meson Production, M. J. Amaryan, G. Gavalian, C. Nepali, M. V. Polyakov, W. J. Briscoe, G. E. Dodge, C. E. Hyde, F. Klein, V. Kuznetsov, I. Strakovsky, J. Zhang

Physics Faculty Publications

We report observation of a narrow peak structure at ~1.54 GeV with a Gaussian width σ = 6 MeV in the missing mass of K_S in the reaction γ+p → pK_SK_L. The observed structure may be due to the interference between a strange (or antistrange) baryon resonance in the pK_L system and the φ(K_SK_L) photoproduction leading to the same final state. The statistical significance of the observed excess of events estimated as the log-likelihood ratio of the resonant signal + background hypothesis and the φ-production-based background-only hypothesis …

Comparison Of Forward And Backward Pp Pair Knockout In 3He(E,E'Pp)N, H. Baghdasaryan, L. B. Weinstein, J. M. Laget, K. P. Adhikari, M. Aghasyan, M. J. Amaryan, M. Anghinolfi, J. Ball, M. Battaglieri, A. S. Biselli, G. Dodge, C. E. Hyde, S. E. Kuhn, H. Seraydaryan

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 (p …

Energy And System Size Dependence Of Two- And Four-Particle Ν2 Measurements In Heavy-Ion Collisions At √ˢᴺᴺ = 62.4 And 200 Gev And Their Implications On Flow Fluctuations And Nonflow, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, A. V. Alakhverdyants, M. Bueltmann, Star Collaboration

Physics Faculty Publications

We present STAR measurements of azimuthal anisotropy by means of the two- and four-particle cumulants ν₂ ν₂{2} and ν₂{4}) for Au + Au and Cu + Cu collisions at center-of-mass energies √ˢᴺᴺ = 62.4 and 200 GeV. The difference between ν₂{2}² and ν₂{4}² is related to ν₂fluctuations (σ_ν2) and nonflow (δ₂). We present an upper limit to σ_ν2/ν₂. Following the assumption that eccentricity fluctuations σ_ε dominate ν₂ fluctuations σ_ν2/ν_{2 ≈ σε/ε} we …

Virtual Compton Scattering And The Generalized Polarizabilities Of The Proton At Q2 = 0.92 And 1.76 Gev2, H. Fonvielle, G. Laveissiere, N. Degrande, C. Jutier, L. Todor, G. E. Dodge, C. E. Hyde, K. Mccormick, P. E. Ulmer, L. B. Weinstein

Physics Faculty Publications

Virtual Compton scattering (VCS) on the proton has been studied at the Jefferson Laboratory using the exclusive photon electroproduction reaction ep → epγ. This paper gives a detailed account of the analysis which has led to the determination of the structure functions P_LL − P_TT/ε and P_LT and the electric and magnetic generalized polarizabilities (GPs) α_E(Q²)and β_M(Q²) at values of the four-momentum transfer squared Q² = 0.92 and 1.76 GeV². These data, together with the results of VCS experiments at lower momenta, help building a …