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Rahbar, A.; Aas, B.; Bleszyński, E.; Bleszynski, M.; Haji‐Saeid, M.; Igo, G.; Irom, F.; Pauletta, G.; Wang, A.T.M.; McClelland, J. B.; Amann, J. F.; Carey, T. A.; Cornelius, W. D.; Barlett, Martin L; Hoffmann, G. W.; Glashausser, C.; Nanda, S.; Gazzaly, M.

doi:10.1103/physrevlett.47.1811

Cited by 86 publications

(6 citation statements)

References 12 publications

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“…Outgoing proton polarizations were determined by the HRS focal-plane polarimeter in a manner discussed in detail recently. 13,14 The beam polarization was continuously monitored with in-beam polarimeters and use of the quench-ratio method. 15 The measurements for Pb consisted of five settings of the magnetic field of the HRS covering the broad quasielastic peak centered at an excitation energy co = 66 MeV.…”

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confidence: 99%

Inclusive Scattering of 500-MeV Protons and Pionic Enhancement of the Nuclear Sea-Quark Distribution

et al. 1984

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We have measured a complete set of polarization-transfer observables in the inclusive scattering of 500-MeV protons from 2 H and Pb at # = 1.75 fm -1 ., Axial longitudinal and transverse response functions derived from these data show no differences between Pb and 2 H. This implies no enhancement of the nuclear pion field in heavy nuclei and consequently that models of the low-* A dependence of certain nuclear structure functions requiring such an enhancement are unlikely to be correct.PACS numbers: 25.40.Ep, 24.70. + sThe recent discovery of significant differences 1 between the F 2 structure functions of 2 H and Fe has aroused much interest in both the nuclear-and particle-physics communities. This so-called European Muon Collaboration (EMC) effect 1 is strong evidence that some constituents of nuclear matter behave quite differently in a large nucleus compared with free (or almost free, as in deuterium) nucleons. The question of what specific quark or quark-cluster phenomena give rise to the enhancement in F\ Q /Ff in the region of the scaling variable x ^ 0.3 has been the subject of numerous calculations. 2 " 10 One possibility, closely connected to current issues in medium-energy physics, is that the enhancement in F\* at small x is due to the nuclear pion field. 2 " 5 For many years it has been conjectured that the pion field might be enhanced in a region of momentum transfer q -2 fm -1 ; extreme enhancements, currently out of favor, would lead to a low critical density for pion condensation. Scattering of a lepton by such an enhanced field naturally leads to increased scattering in the range x ~~ mJm N \ thus pions seem an intuitively appealing candidate for understanding the low-x EMC effect.The most direct probe of the nuclear pion field is the nucleon, which couples to other nucleons via pion exchange. Under suitable approximation (discussed below) the axial-longitudinal coupling of the nucleon to the pion field may be isolated from other couplings by measuring a complete set of polarization-transfer observables 11 " 13 and forming the longitudinal spin-flip probability, S L .We have measured a complete set of polarization-transfer observables for the inclusive excitation of the quasielastic continuum in 2 H and natural Pb with 500-MeV protons. At a momentum transfer of 1.75 fm -1 we find no enhancement of the longitudinal spin-flip probability for Pb compared with 2 H. We believe that this is strong evidence against any enhancement in the nuclear pion field in this range of momentum transfer; this in turn casts serious doubt on explanations of the EMC effect requiring excess pions. [2][3][4][5] Beams of 500-MeV protons alternately polarized normal to the reaction plane (N), longitudinally (along the beam, L), and sideways (S = NxL) were provided by the Clinton P. Anderson Meson Physics Facility (LAMPF). Protons inelastically scattered at 0i ab = 18.5° from natural Pb foils and a liquid deuterium target were momentum analyzed in the high-resolution spectrometer (HRS). Outgoing proton polarizations were ...

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Inclusive Scattering of 500-MeV Protons and Pionic Enhancement of the Nuclear Sea-Quark Distribution

et al. 1984

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“…We have analysed the bulk of the existing experimental data (mainly from LAMPF, IUCF and TRIUMF accelerators [8][9][10][11][12]) for elastic proton scattering at several energies: 160, 180, 200, 280, 400, ,489, 500 and 800 MeV, from two target nuclei, namely; 58 Ni and 90 Zr. The experimental data consists of , in all cases, the differential cross section and analysing power measurements at many scattering angles.…”

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Proton Elastic Scattering from 58Ni and 90Zr at Intermediate Energy

El-moneim¹,

El-Nohy²,

Elzaher³

et al. 2012

JNPP

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Elastic proton scattering at energies between 160 and 800 MeV from 58Ni and 90Zr has been studied within the global Dirac optical model. In this work we calculate potential parameters which give good fits to the experimental data using parameterization code comprising differential cross section and analysing power measurements using DWUCK4. The real and imaginary potentials are well determined and behave regularly with energy. The behaviour of the real central effective potential shows the development of a "wine-bottle" shape in the transition energy region and the persistence of a small attractive potential in the nuclear surface region, even at 800 MeV.

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“…'(p', p)= g a"V", PBr n =1 Par Br 2& t '(P, P2~P P2) (23) where PB E+ 2 (24) such that the scattering amplitude obeys the optical…”

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Boost, recoil, and Wigner rotation effects on no-pair analyses of proton elastic scattering

Tjon

Wallace

1991

Phys. Rev. C

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The relativistic "no-pair" potential for elastic proton scattering is shown to reduce to a conventional tp form using optimal factorization of the optical potential and the impulse approximation. The nucleon-nucleon t matrix is needed in the Breit frame and it may be obtained by boosting the NN c.m. frame t matrix. It is shown that the general form of the boost involves a Mufller factor, Wigner rotation operators acting on spins, and a Lorentz boost of momentum arguments. The reduction to tp form clarifies how the no-pair analysis differs from conventional Watson or Kerman, McManus, and Thaler (KMT) analyses which usually omit Wigner rotation effects and use a Galilean boost of momentum arguments of the t matrix instead of a Lorentz boost. Recent calculations in momentum space have found rather minor off-shell effects based on the no-pair analysis but other calculations have reported substantial effects based on the KMT formalism. Off-shell effects owing to the momentum dependence of the NN t matrix are found to be considerably smaller than the difference between published no-pair and KMT calculations. It is shown that technical differences, predominantly caused by use of a Galilean boost and inaccurate Coulomb corrections, are capable of explaining the disparate results at least at 200

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First Measurement of the Spin Rotation ParameterQforp-Ca40

Cited by 86 publications

References 12 publications

Inclusive Scattering of 500-MeV Protons and Pionic Enhancement of the Nuclear Sea-Quark Distribution

Inclusive Scattering of 500-MeV Protons and Pionic Enhancement of the Nuclear Sea-Quark Distribution

Proton Elastic Scattering from 58Ni and 90Zr at Intermediate Energy

Boost, recoil, and Wigner rotation effects on no-pair analyses of proton elastic scattering

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