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9 results on '"P.A.M. Guichon"'

1. Two photon effects in electron scattering

Author

P.A.M. Guichon

Subjects
Physics, Nuclear and High Energy Physics, Two-photon excitation microscopy, Hadron, Linearity, Nuclear fusion, Born approximation, Atomic physics, Nuclear Experiment, Polarization (waves), Electron scattering
Abstract

The apparent discrepancy between the Rosenbluth and the polarization transfer method for the ratio of the electric to magnetic proton form factors can be explained by a two-photon exchange correction which does not destroy the linearity of the Rosenbluth plot. Though intrinsically small, of the order of a few percent of the cross section, this correction is kinematically enhanced in the Rosenbluth method while it is small for the polarization transfer method, at least in the range of Q 2 where it has been used until now.

Published
2005
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2. Virtual compton scattering under π0 threshold at Q2=0.33 GeV2. Preliminary results

Author

P. Bartsch, J.E. Ducret, I. Ewald, Ch. Hyde-Wright, P. Vernin, G. Quemener, R. Geiges, R. Van de Vyver, G. Tamas, Marc Vanderhaeghen, A. Wagner, P. Merle, N. d'Hose, O. Ravel, R. Edelhoff, P.Y. Bertin, J. Van de Wiele, M. Kahrau, Vincent Breton, J.M. Friedrich, J. Martino, J. Roche, H. Kramer, Th. Gousset, E. A. J. M. Offermann, W.U. Boeglin, D. Lhuillier, G. Rosner, T. Caprano, A. Liesenfeld, P.A.M. Guichon, P. Sauer, S. Derber, N. Degrande, M. O. Distler, R. Böhm, K. Merle, H. Holvoet, P. Jennewein, V. Kunde, Y. Roblin, J. Berthot, G. De Meyer, C. Marchand, S. Kerhoas, D. Marchand, J. Y. Mougey, B. Lannoy, Th. Pospischil, H. Schmieden, Michael Tytgat, Harald Merkel, H. Fonvieille, Th. Walcher, L. Van Hoorebeke, S. Schardt, Dirk Ryckbosch, K. W. Krygier, R. Neuhausen, S. Wolf, and M. Korn

Subjects
Physics, Massless particle, Nuclear reaction, Elastic scattering, Nuclear physics, Nuclear and High Energy Physics, Photon, Scattering, Momentum transfer, Compton scattering, Virtual particle, Atomic physics, Nuclear Experiment
Abstract

We have measured the absolute unpolarized cross sections for photon electro-production off the proton ep → epγ with the Three-Spectrometer-Setup at MAMI at a momentum transfer q=600 MeV/c and a virtual photon polarization ɛ=0.62. The momentum q ′ of the outgoing real photon range from 33 to 111 MeV/c. We extracted two combinations of the recently introduced generalized polarizabilities [1,2].

Published
1999
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3. The (3He, t) reaction as a probe of the nuclear pionic mode

Author

P.A.M. Guichon, J. Delorme, Institut de Physique Nucléaire de Lyon (IPNL), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), and Flores, Sylvie

Subjects
Physics, Nuclear and High Energy Physics, Photon, 010308 nuclear & particles physics, Nuclear Theory, Mode (statistics), 01 natural sciences, Resonance (particle physics), Interpretation (model theory), Nuclear physics, Pion, 0103 physical sciences, Atomic physics, Nuclear Experiment, 010306 general physics, Excitation
Abstract

We present a theoretical interpretation of the ( 3 He, t) reaction on nuclei in the Δ resonance region. Our model is consistent with the constraints from pion and photon excitation channels. A sizeable part of the observed downward shift of the resonance is shown to be ascribable to a hitherto undetected nuclear mode at high excitation, the pionic branch. Interpretation of seemingly adverse results is discussed.

Published
1991
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4. The first determination of Generalized Polarizabilities of the proton by a Virtual Compton Scattering experiment

Author

M. Weiss, G. De Meyer, J. Marroncle, J. Van de Wiele, Vincent Breton, M. O. Distler, Dirk Ryckbosch, N. d'Hose, D. Marchand, B. Lannoy, Ch. Hyde-Wright, S. Kerhoas, R. Böhm, H. Schmieden, C. Marchand, Th. Walcher, Marc Vanderhaeghen, J.M. Friedrich, J. Martino, H. Holvoet, J. Roche, Michael Tytgat, G. Quéméner, A. Liesenfeld, P. Vernin, N. Degrande, R. Neuhausen, W.U. Boeglin, Harald Merkel, Y. Roblin, P.A.M. Guichon, U. Müller, J. Berthot, Daniela Rohe, D. Lhuillier, K. W. Krygier, P.Y. Bertin, A. Wagner, O. Ravel, M. Kahrau, Th. Pospischil, P. Merle, R. Van de Vyver, G. Tamas, P. Bartsch, J.E. Ducret, J. Y. Mougey, I. Ewald, P. Jennewein, L. Van Hoorebeke, D. Baumann, G. Rosner, H. Fonvieille, S. Derber, M. Ding, Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (DAPNIA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Arxiv, Import

Subjects
Physics, Photon, [PHYS.HEXP] Physics [physics]/High Energy Physics - Experiment [hep-ex], Proton, Center-of-momentum frame, 010308 nuclear & particles physics, Compton scattering, FOS: Physical sciences, General Physics and Astronomy, Virtual particle, Polarization (waves), 01 natural sciences, 3. Good health, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), Polarizability, 0103 physical sciences, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], Atomic physics, 010306 general physics, Nuclear Experiment, Microtron
Abstract

Absolute differential cross sections for the reaction (e+p -> e+p+gamma) have been measured at a four-momentum transfer with virtuality Q^2=0.33 GeV^2 and polarization \epsilon = 0.62 in the range 33.6 to 111.5 MeV/c for the momentum of the outgoing photon in the photon-proton center of mass frame. The experiment has been performed with the high resolution spectrometers at the Mainz Microtron MAMI. From the photon angular distributions, two structure functions which are a linear combination of the generalized polarizabilities have been determined for the first time., Comment: 4 pages, 3 figures

Published
2000

5. Virtual Compton Scattering and polarizabilities

Author

P.Y. Bertin, Ch. Hyde-Wright, J.E. Ducret, P. Vernin, S. Kerhoas, M. Weiss, D. Lhuillier, P. Merle, S. Derber, J. Van de Wiele, Daniela Rohe, O. Ravel, Vincent Breton, M. Ding, G. Tamas, J. Mougey, D. Baumann, C. Marchand, A. Wagner, N. D'Hose, K. W. Krygier, Th. Walcher, P. Jennewein, N. Degrande, M. Kahrau, Th. Pospischil, Marc Vanderhaeghen, U. Müller, H. Holvoet, B. Lannoy, P. Bartsch, W.U. Boeglin, P.A.M. Guichon, M. O. Distler, I. Ewald, Y. Roblin, J. Martino, G. Quemener, H. Schmieden, J. Berthot, Michael Tytgat, R. Van de Vyver, G. De Meyer, J.M. Friedrich, D. Marchand, Harald Merkel, G. Rosner, H. Fonvieille, R. Neuhausen, L. Van Hoorebeke, Dirk Ryckbosch, R. Böhm, A. Liesenfeld, J. Marroncle, Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Electromagnetic field, Physics, Nuclear and High Energy Physics, Particle physics, Proton, 010308 nuclear & particles physics, Nuclear Theory, Compton scattering, Measure (physics), Observable, 01 natural sciences, Nuclear physics, Pion, 0103 physical sciences, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], 010306 general physics, Nucleon, Nuclear Experiment, Microtron
Abstract

Virtual Compton Scattering (VCS) off the proton below pion threshold allows access to generalized polarizabilities of the proton. These observables measure the response of the nucleon to low energy electromagnetic field perturbations. This paper presents a comparison with Real Compton Scattering and also results for the first dedicated VCS experiment performed at the Mainz Microtron MAMI with high resolution spectrometers at Q2 = 0.33 GeV2.

Published
1999

6. The first dedicated Virtual Compton Scattering experiment at MAMI

Author

J.M. Friedrich, O. Ravel, A. Wagner, I. Ewald, Ch. Hyde-Wright, M. Kahrau, E. A. J. M. Offermann, P. Sauer, W.U. Boeglin, P. Vernin, A. Liesenfeld, P.A.M. Guichon, J. Martino, R. Edelhoff, G. Rosner, S. Derber, M. Ding, H. Fonvieille, N. d'Hose, M. O. Distler, P.Y. Bertin, Daniela Rohe, R. Neuhausen, G. Tamas, T. Caprano, J.E. Ducret, J. Y. Mougey, D. Baumann, J. Roche, Th. Pospischil, C. Marchand, K. Merle, V. Kunde, M. Korn, Dirk Ryckbosch, R. Böhm, P. Jennewein, K. W. Krygier, P. Merle, B. Lannoy, J. Berthot, G. Quemener, L. Van Hoorebeke, Marc Vanderhaeghen, J. Van de Wiele, Vincent Breton, Michael Tytgat, P. Bartsch, Y. Roblin, R. Van de Vyver, H. Schmieden, R. Geiges, Harald Merkel, H. Kramer, H. Holvoet, G. De Meyer, D. Marchand, Th. Gousset, N. Degrande, Th. Walcher, S. Kerhoas, S. Schardt, D. Lhuillier, Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), and Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Nuclear and High Energy Physics, Photon, Proton, Spectrometer, 010308 nuclear & particles physics, Momentum transfer, Compton scattering, 01 natural sciences, Nuclear physics, Momentum, Amplitude, 0103 physical sciences, Photon polarization, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], Nuclear Experiment, 010306 general physics
Abstract

We measured the absolute cross sections for photon electro-production off the proton, ep to ep gamma , with the high resolution spectrometers at MAMI at momentum transfer q=600 MeV/c and photon polarization epsilon =0.62. We covered the momentum range for the outgoing real photon q'=33/111 MeV/c. From the extracted virtual Compton scattering amplitude we deduce values for two structure functions related to the generalized polarizabilities of the proton.

Published
1999

7. The first Virtual Compton Scattering experiment at MAMI

Author

V. Kunde, Y. Roblin, A. Liesenfeld, P. Sauer, J. Berthot, P. Merle, P.Y. Bertin, J. Martino, Marc Vanderhaeghen, J. Roche, K. Merle, H. Schmieden, J.M. Friedrich, T. Caprano, S. Kerhoas, S. Schardt, R. Böhm, Daniela Rohe, G. Tamas, M. O. Distler, G. Quéméner, R. Van de Vyver, A. Wagner, O. Ravel, Harald Merkel, Th. Pospischil, Th. Gousset, J.E. Ducret, J. Y. Mougey, I. Ewald, N. d'Hose, P. Jennewein, N. Degrande, Th. Walcher, Michael Tytgat, D. Lhuillier, Ch. Hyde-Wright, R. Edelhoff, G. Rosner, G. De Meyer, H. Fonvieille, D. Marchand, P. Vernin, S. Derber, M. Kahrau, H. Kramer, J. Van de Wiele, Vincent Breton, P. Bartsch, W.U. Boeglin, M. Ding, P.A.M. Guichon, H. Holvoet, R. Geiges, C. Marchand, B. Lannoy, L. Van Hoorebeke, K. W. Krygier, Dirk Ryckbosch, R. Neuhausen, M. Korn, Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), De Sanctis E. Bianchi N. Muccifora V., VCS, Chadelas, Michèle, and Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Nuclear and High Energy Physics, [PHYS.HEXP] Physics [physics]/High Energy Physics - Experiment [hep-ex], Proton, Spectrometer, 010308 nuclear & particles physics, Compton scattering, Virtual particle, Observable, 01 natural sciences, 7. Clean energy, Nuclear physics, 0103 physical sciences, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], Nuclear Experiment, 010306 general physics, Microtron
Abstract

Virtual Compton scattering, i.e. the exclusive reaction γ ∗ p → γ′p′ with γ ∗ denoting a virtual photon, provides new insights on the internal structure of the proton. Below π 0 production threshold, this experiment measures the generalized polarizabilities of the proton as defined by Guichon et al [1], [2] and Drechsel et al [3]. These new electromagnetic observables, functions of Q 2 , enlarge the concept of electric (α0 and magnetic (β) polarizabilities in Real Compton Scattering ( Q 2 =0) [4]. The first VCS experiment [5] of this kind was measured at the three spectrometer facility at the Mainz Microtron MAMI for Q 2 =0.33 GeV 2 and we present in this paper the preliminary results.

Published
1999

8. Compton scattering and the nucleon valence wavefunction

Author

P.A.M. Guichon, Marc Vanderhaeghen, J. Van de Wiele, Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Robert, Suzanne

Subjects
Physics, Quark, Nuclear and High Energy Physics, Particle physics, [PHYS.HEXP] Physics [physics]/High Energy Physics - Experiment [hep-ex], 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, Nuclear Theory, Compton scattering, Compton wavelength, Inelastic scattering, 01 natural sciences, Scattering amplitude, Amplitude, 0103 physical sciences, [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], Nuclear Experiment, 010306 general physics, Nucleon, Wave function
Abstract

Calculations are presented for real Compton scattering on the nucleon in a PQCD formalism by starting from different quark distribution amplitudes of the nucleon. In a second step we present the formalism to extract this distribution amplitude in a model independent way from hard exclusive Compton scattering data.

Published
1996

9. Exchange current corrections for partial capture rates of muons in nuclei

Author

M. Giffon, J. Joseph, C. Samour, P.A.M. Guichon, R. Laverrière, Flores, Sylvie, Institut de Physique Nucléaire de Lyon (IPNL), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Muon, 010308 nuclear & particles physics, Nuclear Theory, Elementary particle, 01 natural sciences, Nuclear physics, Amplitude, Pion, State dependent, 0103 physical sciences, Nuclear fusion, Current (fluid), Nuclear Experiment, 010306 general physics
Abstract

A calculation is made of exchange current corrections for partial capture rates of muons in12C,16O,32S and40Ca nuclei. One-pion exchange is taken into account. Adler-Dothan's results are used to obtain the weak pion production amplitude. The nuclear states are described in the Tamm-Dancoff approximation. It is found that the corrections are very erratic and state dependent. A large effect is found for the 0+→0− transitions due to the size of the time part of the axial exchange current.

Published
1978

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