P Ambrozewicz

Publications (174)199.87 Total impact

• Source

  Available from: John Robert Arrington

  Conference Proceeding: Electroproduction of kaons on light nuclei

  B. Zeidman, D. Abbott, A. Ahmidouch, P. Ambrozewicz, C. S. Armstrong, J. Arrington, R. Asaturyan, K. Assamagan, S. Avery, K. Bailey, [......], S. Tajima, L. Tang, B. Terburg, A. Uzzle, S. Wood, H. Yamaguchi, C. Yan, L. Yuan, M. Zeier, B. Zihlmann
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  ABSTRACT: The A(e,eiK+)YX reaction on H, D, {sup 3}He, and {sup 4}He was investigated in Hall C at CEBAF. Data were obtained for Q{sup 2} {approx} 0.35 and 0.5 GeV{sup 2} at 3.245 GeV. The missing mass spectra for both H and D are fitted with Monte-Carlo simulations incorporating peaks corresponding to Lambda production on the proton and Sigma production on both the proton and neutron. For D, the cross section ratio Sigma{sup 0}/Sigma{sup -} {approx} 2, and excess yield close to the thresholds for Lambda and Sigma production can be attributed to final-state interactions; models are compared to the data. The analysis of the data for the He targets is in a more preliminary state with broader quasi-free peaks resulting from the higher Fermi momenta. Evidence for bound Lambda-hypernuclear states is seen and other structure may be present.
  08/2001
• Article: Electroproduction of kaons and light hypernuclei

  J. Reinhold, D. Abbott, A. Ahmidouch, P. Ambrozewicz, C.S. Armstrong, J. Arrington, R. Asaturyan, K. Assamagan, S. Avery, K. Bailey, [......], L. Tang, B. Terburg, A. Uzzle, S. Wood, H. Yamaguchi, C. Yan, L. Yuan, B. Zeidman, M. Zeier, B. Zihlmann
  Nuclear Physics A 03/2001; 684:470. · 1.54 Impact Factor
• Article: Associated Λ production at Jefferson Lab

  O. K. Baker, S. Avery, K. Assamagan, K. Beard, J. Cha, T. Eden, P. Gueye, W. Hinton, M. Harvey, C. Keppel, [......], E. Hungerford, W. Kim, K. Kino, M. Maeda, T. Saito, T. Terasawa, H. Tsubota, L. Kramer, P. Markowitz, B. A. Raue
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  ABSTRACT: The 1H(e,e'K+)Λ and 1H(e,e'K+)Σ0 reactions were studied as a function of the squared four-momentum-transfer, Q2, and the virtual photon polarization, ɛ, thus enabling the separation of the longitudinal and transverse parts of the cross section. The existence of a sizable longitudinal component for the 1H(e,e'K+)Λ reaction seems to be indicated by these data.
  Nuclear Physics A 07/1998; 639:189-196. · 1.54 Impact Factor
• Source

  Available from: W. J. Briscoe

  Article: Cascade production in the reactions γp→ K^{+} K^{+}(X) and γp→ K^{+} K^{+} π^{-}(X)

  + Γp, L Guo, D P Weygand, M Battaglieri, R De Vita, V Kubarovsky, P Stoler, M J Amaryan, P Ambrozewicz, M Anghinolfi, [......], D P Watts, L B Weinstein, M Williams, E Wolin, M H Wood, A Yegneswaran, L Zana, J Zhang, B Zhao, Z W Zhao
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  ABSTRACT: Photoproduction of the cascade resonances has been investigated in the reactions γp → K + K + (X) and γp → K + K + π − (X). The mass splitting of the ground state (Ξ − , Ξ 0) doublet is measured to be 5.4 ± 1.8 MeV/c 2 , consistent with existing measurements. The differential (total) cross sections for the Ξ − have been determined for photon beam energies from 2.75 to 3.85 (4.75) GeV, and are consistent with a production mechanism of Y * → K + Ξ − through a t-channel process. The reaction γp → K + K + π − [Ξ 0 ] has also been investigated in search of excited cascade resonances. No significant signal of excited cascade states other than the Ξ − (1530) is observed. The cross section results of the Ξ − (1530) have also been obtained for photon beam energies from 3.35 to 4.75 GeV.
  01/1920; 8(15):10-33.
• Source

  Available from: W. J. Briscoe

  Article: Deeply virtual and exclusive electroproduction of ω-mesons

  The Clas, L Morand, D Doré, M Garçon, M Guidal, J.-M Laget, S Morrow, F Sabatié, E Smith, G Adams, [......], J Shaw, A V Skabelin, V Vlassov, L B Weinstein, D P Weygand, M Williams, E Wolin, M H Wood, A Yegneswaran, L Zana
  S.S. Stepanyan B.E. Stokes I.I. Strakovsky D.J. Tedeschi. 1421262913193335(33).
• Article: Kaon electroproduction on deuterium

  J. Reinhold, D. Abbott, A. Ahmidouch, P. Ambrozewicz, C.S. Armstrong, J. Arrington, K. Assamagan, K. Bailey, O.K. Baker, S. Beedoe, [......], J.P. Schiffer, R.E. Segel, S. Stepanyan, V. Tadevosian, L. Tang, B. Terburg, S. Wood, C. Yan, B. Zeidman, B. Zihlmann
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  ABSTRACT: Kaon electroproduction on deuterium and hydrogen targets has been measured at beam energies of 3.245 and 2.445 GeV and momentum transfer Q2 = 0.38 and 0.5 (GeV/c)2. Associated Λ production off a proton in the deuteron exhibits a quasifree production mechanism. The electroproduction of a Σ− off the neutron could be extracted for the first time with reasonable errors.
  Nuclear Physics A. 639:197.
• Article: Radiative decays of the Σ0(1385) and Λ(1520) hyperons

  S. Taylor, G. S. Mutchler, G. Adams, P. Ambrozewicz, E. Anciant, M. Anghinolfi, B. Asavapibhop, G. Asryan, G. Audit, H. Avakian, [......], L. B. Weinstein, H. Weller, D. P. Weygand, C. S. Whisnant, M. Williams, E. Wolin, M. H. Wood, A. Yegneswaran, J. Yun, L. Zana
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  ABSTRACT: The electromagnetic decays of the Σ0(1385) and Λ(1520) hyperons were studied in photon-induced reactions γp→K+Λ(1116)γ in the Large Acceptance Spectrometer detector at the Thomas Jefferson National Accelerator Facility. We report the first observation of the radiative decay of the Σ0(1385) and a measurement of the Λ(1520) radiative decay width. For the Σ0(1385)→Λ(1116)γ transition, we measured a partial width of 479±120(stat)-100+81(sys) keV, larger than all of the existing model predictions. For the Λ(1520)→Λ(1116)γ transition, we obtained a partial width of 167±43(stat)-12+26(sys) keV.
  Phys. Rev. C. 71(5).
• Article: Measurement of longitudinal and transverse cross sections in the 3He(e,e′π+)3H reaction at W=1.6 GeV

  D. Gaskell, A. Ahmidouch, P. Ambrozewicz, H. Anklin, J. Arrington, K. Assamagan, S. Avery, K. Bailey, O. K. Baker, S. Beedoe, [......], T. Takahashi, L. Tang, B. Terburg, D. Van Westrum, J. Volmer, T. P. Welch, S. Wood, L. Yuan, B. Zeidman, B. Zihlmann
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  ABSTRACT: The coherent 3He(e,e′π+)3H reaction was measured at Q2=0.4 (GeV/c)2 and W=1.6 GeV for two values of the virtual photon polarization, ε, allowing the separation of longitudinal and transverse cross sections. The results from the coherent process on 3He were compared to H(e,e′π+)n data taken at the same kinematics. This marks the first direct comparison of these processes. At these kinematics (pπ=1.1 GeV/c), pion rescattering from the spectator nucleons in the 3He(e,e′π+)3H process is expected to be small, simplifying the comparison to π+ production from the free proton.
  Phys. Rev. C. 65(1).
• Article: Longitudinal Electroproduction of Charged Pions from 1H, 2H, and 3He

  A. Ahmidouch, P Ambrozewicz, H. Anklin, J. Arrington, D. Gaskell
• Source

  Available from: John Robert Arrington

  Article: Separation of the longitudinal and transverse cross sections in the $^{1}H(e,e'K^{+})\Lambda$ and $^{1}H(e,e'K^{+})\Sigma^{0}$ reactions

  R. M. Mohring, D. Abbott, A. Ahmidouch, T.A. Amatuni, P Ambrozewicz, T Angelescu, C. S. Armstrong, J. Arrington, K. Assamagan, S. Avery, [......], T Terasawa, H. Tsubota, G. M. Urciuoli, J Volmer, W. Vulcan, T.P. Welch, R Williams, S. Wood, C Yan, B. Zeidman
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  ABSTRACT: We report measurements of cross sections for the reaction p(e,e'K)Y, for both the Lambda and Sigma_0 hyperon states, at an invariant mass of W=1.84 GeV and four-momentum transfers 0.5<Q2<2 (GeV/c)2. Data were taken for three values of virtual photon polarization, allowing the decomposition of the cross sections into longitudinal and transverse components. The Lambda data is a revised analysis of prior work, whereas the Sigma_0 results have not been previously reported.
• Article: Measurement of beam-spin asymmetries for π⁺ electroproduction above the baryon resonance region

  H Avakian, V D Burkert, L Elouadrhiri, N. Bianchi, G Adams, A. Afanasev, P Ambrozewicz, E Anciant, M Anghinolfi, D. S. Armstrong, [......], H Weller, D P Weygand, C S Whisnant, E Wolin, M H Wood, A Yegneswaran, J Yun, B Zhang, J Zhao, Z Zhou
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  ABSTRACT: We report the first evidence for a nonzero beam-spin azimuthal asymmetry in the electroproduction of positive pions in the deep-inelastic kinematic region. Data for the reaction ep→e'pi(+)X have been obtained using a polarized electron beam of 4.3 GeV with the CEBAF Large Acceptance Spectrometer at the Thomas Jefferson National Accelerator Facility. The amplitude of the sin phi modulation increases with the momentum of the pion relative to the virtual photon, z. In the range z=0.5-0.8 the average amplitude is 0.038+/-0.005+/-0.003 for a missing mass M-X gt 1.1 GeV and 0.037+/-0.007+/-0.004 for M-X gt 1.4 GeV
• Article: First measurement of transferred polarization in the exclusive ep to e'K/sup +/ Lambda reaction

  D S Carman, K Joo, M D Mestayer, B A Raue, G Adams, P Ambrozewicz, E Anciant, M Anghinolfi, D. S. Armstrong, B Asavapibhop, [......], H Weller, D P Weygand, C S Whisnant, E Wolin, M H Wood, A Yegneswaran, J Yun, B Zhang, J Zhao, Z Zhou
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  ABSTRACT: The first measurements of the transferred polarization for the exclusive ep to e'K + Lambda reaction have been performed at Jefferson Laboratory using the CLAS spectrometer. A 2.567 GeV beam was used to measure the hyperon polarization over Q/sup 2/ from 0.3 to 1.5 (GeV/c)/sup 2/, W from 1.6 to 2.15 GeV, and over the full K/sup +/ center-of-mass angular range. Comparison with predictions of hadrodynamic models indicates strong sensitivity to the underlying resonance contributions. A nonrelativistic quark-model interpretation of our data suggests that the ss quark pair is produced with spins predominantly antialigned. Implications for the validity of the most widely used quark-pair creation operator are discussed.
• Source

  Available from: A. Deppman

  Article: Complete angular distribution measurements of two-body deuteron photodisintegration between 0.5 and 3 GeV

  M Mirazita, F Ronchetti, P Rossi, E De Sanctis, G Adams, P Ambrozewicz, E Anciant, M Anghinolfi, B Asavapibhop, G Audit, [......], L B Weinstein, H Weller, D P Weygand, C S Whisnant, E Wolin, M H Wood, A Yegneswaran, J Yun, B Zhang, Z Zhou
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  ABSTRACT: Nearly complete angular distributions of the two-body deuteron photodisintegration differential cross section have been measured using the CEBAF Large Acceptance Spectrometer detector and the tagged photon beam at the Thomas Jefferson National Accelerator Facility. The data cover photon energies between 0.5 and 3.0 GeV and center-of-mass proton scattering angles 10degrees-160degrees. The data show a persistent forward- backward angle asymmetry over the explored energy range, and are well described by the nonperturbative quark gluon string model.
• Article: Two-nucleon momentum distributions measured in ³He(e,e ' pp)n

  R A Niyazov, L B Weinstein, G Adams, P Ambrozewicz, E Anciant, M Anghinolfi, B Asavapibhop, G Asryan, G Audit, T Auger, [......], A V Vlassov, K Wang, H Weller, D P Weygand, C S Whisnant, E Wolin, M H Wood, A Yegneswaran, J Yun, B Zhang
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  ABSTRACT: We have measured the ³He(e,e'pp)n reaction at 2.2 GeV over a wide kinematic range. The kinetic energy distribution for "fast" nucleons (p > 250 MeV/c) peaks where two nucleons each have 20% or less, and the third nucleon has most of the transferred energy. These fast pp and pn pn pairs are back to back with little momentum along the three-momentum transfer, indicating that they are spectators. Calculations by Sargsian and by Laget also indicate that we have measured distorted two- nucleon momentum distributions by striking one nucleon and detecting the spectator correlated pair.
• Article: Measurement of the polarized structure function sigma(LT ') for p((e)over-right-arrow,e(')pi(+))n in the Delta(1232) resonance region

  K Joo, L C Smith, I. G. Aznauryan, V D Burkert, R Minehart, G Adams, P Ambrozewicz, E Anciant, M Anghinolfi, B Asavapibhop, [......], K Wang, L B Weinstein, H Weller, D P Weygand, M Williams, E Wolin, M H Wood, A Yegneswaran, J Yun, L Zana
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  ABSTRACT: The polarized longitudinal-transverse structure function sigma(LT') has been measured using the p((e) over right arrow ,e'pi(+))n reaction in the Delta(1232) resonance region at Q(2)=0.40 and 0.65 GeV2. No previous sigma(LT') data exist for this reaction channel. The kinematically complete experiment was performed at the Jefferson Lab with the CEBAF large acceptance spectrometer using longitudinally polarized electrons at an energy of 1.515 GeV. A partial-wave analysis of the data shows generally better agreement with recent phenomenological models of pion electroproduction compared to the previously measured pi(0)p channel. A fit to both pi(0)p and pi(+)n channels using a unitary isobar model suggests the unitarized Born terms provide a consistent description of the nonresonant background. The t-channel pion pole term is important in the pi(0)p channel through a rescattering correction, which could be model dependent.
• Article: Survey of ALT′ asymmetries in semi-exclusive electron scattering on 4He and 12C

  D. Protopopescu, F.W. Hersman, M. Holtrop, G. Adams, P. Ambrozewicz, E. Anciant, M. Anghinolfi, B. Asavapibhop, G. Asryan, G. Audit, [......], H. Weller, D.P. Weygand, C.S. Whisnant, M. Williams, E. Wolin, M.H. Wood, A. Yegneswaran, J. Yun, L. Zana, B. Zhang
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  ABSTRACT: Single spin azimuthal asymmetries ALT′ were measured at Jefferson Lab using 2.2 and 4.4 GeV longitudinally polarised electrons incident on 4He and 12C targets in the CLAS detector. ALT′ is related to the imaginary part of the longitudinal-transverse interference and in quasifree nucleon knockout it provides an unambiguous signature for final state interactions (FSI). Experimental values of ALT′ were found to be below 5%, typically |ALT′|⩽3% for data with good statistical precision. Optical model in eikonal approximation (OMEA) and relativistic multiple-scattering Glauber approximation (RMSGA) calculations are shown to be consistent with the measured asymmetries.
  Nuclear Physics A.
• Article: Tensor polarization of the ϕ meson photoproduced at high t

  K. McCormick, G. Audit, J. M. Laget, G. Adams, P. Ambrozewicz, E. Anciant, M. Anghinolfi, B. Asavapibhop, T. Auger, H. Avakian, [......], H. Weller, D. P. Weygand, C. S. Whisnant, M. Witkowski, E. Wolin, M. H. Wood, A. Yegneswaran, J. Yun, J. Zhao, Z. Zhou
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  ABSTRACT: As part of a measurement [ E. Anciant et al. Phys. Rev. Lett. 85 4682 (2000)] of the cross section of ϕ meson photoproduction to high momentum transfer, we measured the polar angular decay distribution of the outgoing K+ in the channel ϕ→K+K− in the ϕ center-of-mass frame (the helicity frame). We find that s-channel helicity conservation (SCHC) holds in the kinematical range where t-channel exchange dominates (up to −t∼2.5 GeV2 for Eγ=3.6 GeV). Above this momentum, u-channel production of a ϕ meson dominates and induces a violation of SCHC. The deduced value of the ϕNN coupling constant lies in the upper range of previously reported values.
  Phys. Rev. C. 69(3).
• Article: Measurement of the polarized structure function σLT′ for p(e⃗,e′p)π0 in the Δ(1232) resonance region

  K. Joo, L. C. Smith, V. D. Burkert, R. Minehart, G. Adams, P. Ambrozewicz, E. Anciant, M. Anghinolfi, B. Asavapibhop, G. Audit, [......], L. B. Weinstein, H. Weller, D. P. Weygand, C. S. Whisnant, E. Wolin, M. H. Wood, A. Yegneswaran, J. Yun, J. Zhao, Z. Zhou
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  ABSTRACT: The polarized longitudinal-transverse structure function σLT′ has been measured in the Δ(1232) resonance region at Q2=0.40 and 0.65GeV2. Data for the p(e⃗,e′p)π0 reaction were taken at Jefferson Lab with the CEBAF large acceptance spectrometer (CLAS) using longitudinally polarized electrons at an energy of 1.515 GeV. For the first time a complete angular distribution was measured, permitting the separation of different nonresonant amplitudes using a partial wave analysis. Comparison with previous beam asymmetry measurements at MAMI indicate a deviation from the predicted Q2 dependence of σLT′ using recent phenomenological models.
  Phys. Rev. C. 68(3).
• Article: Two-Nucleon Momentum Distributions Measured in^}$$3$$ He (e, e^{$$′$$ pp) n

  RA Niyazov, LB Weinstein, G Adams, P Ambrozewicz, E Anciant, M Anghinolfi, B Asavapibhop, G Asryan, G Audit, T Auger, others
  Physical review letters. 92(5):52303.
• Article: Observation of an exotic S=+ 1 baryon in exclusive photoproduction from the deuteron

  S Stepanyan, K Hicks, DS Carman, E Pasyuk, RA Schumacher, ES Smith, DJ Tedeschi, L Todor, G Adams, P Ambrozewicz, others
  Physical Review Letters. 91(25):252001.