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41 results on '"Bermuth, J."'

1. 3He(e,e′pp) and 3He(e,e′pn) reactions at AmPS and MAMI

Author

Middleton, D. G., Annand, J. R. M., Ases Antelo, M., Ayerbe, C., Barneo, P., Baumann, D., Bermuth, J., Bernauer, J., Blok, H. P., Böhm, R., Bosnar, D., Ding, M., Distler, M. O., Friedrich, J., García Llongo, J., Glazier, D. I., Grabmayr, P., Hehl, T., Heim, J., Hesselink, W. H. A., Jans, E., Jover Mañas, G., Kohl, M., Lapikás, L., MacGregor, I. J. D., Martin, I., McGeorge, J. C., Merkel, H., Merle, P., Monstad, K., Moschini, F., Müller, U., Pérez Benito, R., Pospischil, Th., Potokar, M., Rosner, G., Seimitz, M., de Vries, H., Walcher, Th., Watts, D. P., Weinriefer, M., Weiss, M., and Zihlmann, B.

Published
2008
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2. Separated cross-sections in $ \pi^{0}_{}$ electroproduction at threshold at Q2 = 0.05GeV2/c2

Author

Weis, M., Bartsch, P., Baumann, D., Bermuth, J., Bernstein, A. M., Bohinc, K., Böhm, R., Ding, M., Distler, M. O., Ewald, I., Friedrich, J. M., Friedrich, J., Kahrau, M., Kohl, M., Krygier, K. W., Liesenfeld, A., Merkel, H., Merle, P., Müller, U., Neuhausen, R., Pavan, M. M., Pospischil, Th., Potokar, M., Rosner, G., Schmieden, H., Seimetz, M., Širca, S., Wagner, A., Walcher, Th., and The A1 Collaboration

Published
2008
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3. Measurement of the LT-asymmetry in πelectroproduction at the energy of the Δ(1232)-resonance

Author

Elsner, D., Süle, A., Barneo, P., Bartsch, P., Baumann, D., Bermuth, J., Böhm, R., Bosnar, D., Ding, M., Distler, M., Drechsel, D., Ewald, I., Friedrich, J., Friedrich, J. M., Grözinger, S., Jennewein, P., Kamalov, S., H. Klein, F., Kohl, M., Krygier, K. W., Merkel, H., Merle, P., Müller, U., Neuhausen, R., Pospischil, Th., Potokar, M., Rosner, G., Schmieden, H., Seimetz, M., Strähle, O., Tiator, L., Walcher, Th., and Weis, M.

Published
2006
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4. Measurement of the electric form factor of the neutron at Q2 = 0.3-0.8 (GeV/ c) 2 ⋆

Author

Glazier, D. I., Seimetz, M., Annand, J. R. M., Arenhövel, H., Ases Antelo, M., Ayerbe, C., Bartsch, P., Baumann, D., Bermuth, J., Böhm, R., Bosnar, D., Ding, M., Distler, M. O., Elsner, D., Friedrich, J., Hedicke, S., Jennewein, P., Jover Ma nas, G., Klein, F. H., Klein, F., Kohl, M., Krygier, K. W., Livingston, K., MacGregor, I. J. D., Makek, M., Merkel, H., Merle, P., Middleton, D., Müller, U., Neuhausen, R., Nungesser, L., Ostrick, M., Pérez Benito, R., Pochodzalla, J., Pospischil, Th., Potokar, M., Reiter, A., Rosner, G., Sanner, J., Schmieden, H., Süle, A., Walcher, Th., Watts, D. P., and Weis, M.

Published
2005
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5. Evidence for narrow Δ0(1232) states in the 12 C(e,e'pπ−}11 C Reaction

Author

Bartsch, P., Baumann, D., Bermuth, J., Bohinc, K., Böhm, R., Bosnar, D., Clawiter, N., Derber, S., Ding, M., Distler, M.O., Ebbes, A., Ewald, I., Friedrich, J.M., Friedrich, J., Jennewein, P., Kahrau, M., Kohl, M., Kozlov, A., Krygier, K.W., Kuss, M., Liesenfeld, A., Merkel, H., Merle, P., Müller, U., Neuhausen, R., Pospischil, T., Potokar, M., Rohe, D., Rosner, G., Schmieden, H., Širca, S., Wagner, A., Walcher, T., Weis, M., and Wolf, S.

Published
1999
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6. Photoemission of spinpolarized electrons from strained GaAsP

Author

Drescher, P., Andresen, H. G., Aulenbacher, K., Bermuth, J., Dombol, Th., Fischerz, H., Euteneuer, H., Faleev, N. N., Galaktionov, M. S., v. Harrach, D., Hartmann, P., Hoffmann, J., Jennewein, P., Kaiser, K. H., Köbis, S., Kovalenkov, O. V., Kreide, H. J., Langbeine, J., Mamaev, Y. A., Nachtigall, Ch., Petri, M., Plützer, S., Reicherte, E., Schemies, M., Schöpe, H. -J., Steffens, K. -H., Steigerwald, M., Subashiev, A. V., Trautner, H., Vinokurov, D. A., Yashin, Y. P., and Yavich, B. S.

Published
1996
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7. First measurements of the 16O(e, e'pn)14N reaction

Author

Middleton, D. G., Annand, J. R. M., Barbieri, C., Barneo, P., Bartsch, P., Baumann, D., Bermuth, J., Bosnar, D., Blok, H. P., Böhm, R., Ding, M., Distler, M. O., Elsner, D., Friedrich, J., Giusti, C., Glazier, D. I., Grabmayr, P., Grözinger, S., Hehl, T., Heim, J., Hesselink, W. H. A, Jans, E., Klein, F., Kohl, M., Lapikás, L., MacGregor, I. J. D., Martin, I., McGeorge, J. C., Merkel, H., Merle, P., Moschini, F., Müller, U., Pospischil, Th., Rosner, G., Schmieden, H., Seimetz, M., Süle, A., de Vries, H., Walcher, Th., Watts, D. P., Weis, M., and Zihlmann, B.

Published
2006
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9. Investigation of the Exclusive He3(e,e′pn)H1 Reaction

Author

Middleton, D. G., Annand, J. R M, Antelo, M. Ases, Ayerbe, C., Barneo, P., Baumann, D., Bermuth, J., Bernauer, J., Blok, H. P., Böhm, R., Bosnar, D., Ding, M., Distler, M. O., Friedrich, J., Llongo, J. García, Glazier, D. I., Golak, J., Glöckle, W., Grabmayr, P., Hehl, T., Heim, J., Hesselink, W. H A, Jans, E., Kamada, H., Mañas, G. Jover, Kohl, M., Lapikás, L., MacGregor, I. J D, Martin, I., McGeorge, J. C., Merkel, H., Merle, P., Monstad, K., Moschini, F., Müller, U., Nogga, A., Pérez-Benito, R., Pospischil, Th, Potokar, M., Rosner, G., Seimetz, M., Skibiński, R., De Vries, H., Walcher, Th, Watts, D. P., Weinriefer, M., Weiss, M., Witała, H., and Zihlmann, B.

Subjects
Nuclear Theory, Physics and Astronomy(all), Nuclear Experiment
Abstract

Cross sections for the He3(e,e′pn)H1 reaction were measured for the first time at energy transfers of 220 and 270 MeV for several momentum transfers ranging from 300 to 450MeV/c. Cross sections are presented as a function of the momentum of the recoil proton and the momentum transfer. Continuum Faddeev calculations using the Argonne V18 and Bonn-B nucleon-nucleon potentials overestimate the measured cross sections by a factor 5 at low recoil proton momentum with the discrepancy becoming smaller at higher recoil proton momentum.

Published
2009
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10. Investigation of the Exclusive ^{3}He(e,e'pn)p Reaction

Author

Middleton, D. G., Annand, J. R. M., Antelo, M. Ases, Ayerbe, C., Barneo, P., Baumann, D., Bermuth, J., Bernauer, J., Blok, H. P., Bosnar, D., B��hm, R., Ding, M., Distler, M. O., Friedrich, J., Llongo, J. Garc��a, Glazier, D. I., Golak, J., Gl��ckle, W., Grabmayr, P., Hehl, T., Heim, J., Hesselink, W. H. A., Jans, E., Kamada, H., Ma��as, G. Jover, Kohl, M., Lapik��s, L., MacGregor, I. J. D., Martin, I., McGeorge, J. C., Merkel, H., Merle, P., Monstad, K., Moschini, F., M��ller, U., Nogga, A., Benito, R. P��rez, Pospischil, Th., Potokar, M., Rosner, G., Seimetz, M., Skibi��ski, R., de Vries, H., Walcher, Th., Watts, D. P., Weinriefer, M., Weiss, M., Wita��a, H., and Zihlmann, B.

Subjects
Nuclear Theory, FOS: Physical sciences, Physics::Accelerator Physics, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

Cross sections for the ^{3}He(e,e'pn)p reaction were measured for the first time at energy transfers of 220 and 270 MeV for several momentum transfers ranging from 300 to 450 MeV/c. Cross sections are presented as a function of the momentum of the recoil proton and the momentum transfer. Continuum Faddeev calculations using the Argonne V18 and Bonn-B nucleon-nucleon potentials overestimate the measured cross sections by a factor 5 at low recoil proton momentum with the discrepancy becoming much smaller at higher recoil momentum., 5, pages, 3 figures

Published
2009

11. Investigation of the Exclusive ^{; ; ; 3}; ; ; He(e, e'pn)p Reaction

Author

Middleton, D.G., Annand, J.R.M., Ases Antelo, M., Ayerbe, C., Barneo, P., Baumann, D., Bermuth, J., Bernauer, J., Blok, H.P., Bosnar, Damir, Böhm, R., Ding, M., Distler, M.O., Friedrich, J., García Llongo, J., Glazier, D. G., Golak, J., Glöckle, W., Grabmayr, P., Hehl, T., Heim, J., Hesselink, W.H.A., Jans, E., Kamada, H., Jover Mañ, As, G., Kohl, M., Lapikás, L., MacGregor, I.J.D., Martin, I., McGeorge, J.C., Merkel, H., Merle, P., Monstad, K., Moschini, F., Müller, U., Nogga, A., Pérez Benito, R., Pospischil, Th., Potokar, M., Rosner, G., Seimetz, M., Skibiński, R., de Vries, H., Walcher, Th., Watts, D.P., Weinriefer, M., Weiss, M., Witała, H., and Zihlmann, B.

Subjects
Nuclear Theory, Physics::Accelerator Physics, nuclear reactions, inelastic electron scattering, few-body systems, Forces in hadronic systemf, Nuclear Experiment
Abstract

Cross sections for the ^{; ; ; 3}; ; ; He(e, e'pn)p reaction were measured for the first time at energy transfers of 220 and 270 MeV for several momentum transfers ranging from 300 to 450 MeV/c. Cross sections are presented as a function of the momentum of the recoil proton and the momentum transfer. Continuum Faddeev calculations using the Argonne V18 and Bonn-B nucleon-nucleon potentials overestimate the measured cross sections by a factor 5 at low recoil proton momentum with the discrepancy becoming much smaller at higher recoil momentum.

Published
2009

12. Measurement of the LT-asymmetry in pi(0) electroproduction at the energy of the Delta(1232)-resonance

Author

Elsner, D., Süle, A., Barneo, P., Bartsch, P., Baumann, D., Bermuth, J., Böhm, R., Bosnar, D., Ding, M., Distler, M., Drechsel, D., Ewald, I., Friedrich, J., Friedrich, J. M., Grözinger, S., Jennewein, P., Kamalov, S., Klein, F. H., Kohl, M., Krygier, K. W., Merkel, H., Merle, P., Müller, U., Neuhausen, R., Pospischil, Th., Potokar, M., Rosner, G., Schmieden, H., Strähle, M. Seimetz O., Tiator, L., Walcher, Th., and Weis, M.

Subjects
Meson production, Electromagnetic processes and properties, Baryon resonances, Nuclear Experiment
Abstract

The reaction p(e,e'p)pi^0 has been studied at Q^2=0.2 (GeV/c)^2 in the region of W=1232 MeV. From measurements left and right of q, cross section asymmetries \rho_LT have been obtained in forward kinematics \rho_LT(\theta_\pi^0=20deg) = (-11.68 +/- 2.36_stat +/- 2.36_sys)$ and backward kinematics \rho_LT(\theta_\pi^0=160deg) =(12.18 +/- 0.27_stat +/- 0.82_sys). Multipole ratios \Re(S_1+^* M_1+)/|M_1+|^2 and \Re(S_0+^* M_1+)/|M_1+|^2 were determined in the framework of the MAID2003 model. The results are in agreement with older data. The unusally strong negative \Re(S_0+^* M_1+)/|M_1+|^2 required to bring also the result of Kalleicher et al. in accordance with the rest of the data is almost excluded., Comment: 7 pages, 7 figures, 4 tables. Changed content. Accepted for publication in EPJA

Published
2006

13. The neutron charge form factor and target analyzing powers from 3He-pol.(e-pol., e'n) scattering

Author

Bermuth, J., Merle, P., Carasco, C., Baumann, D., Bohm, D., Bosnar, Damir, Ding, M., Distler, M.O., Friedrich, J., Friedrich, J.M., Golak, J., Glockle, W., Hauger, M., Heil, W., Jennewein, P., Jourdan, J., Kamada, H., Klein, A., Kohl, M., Krusche, B., Krygier, K.W., Merkel, H., Muller, U., Neuhausen, R., Nogga, A., Normand, C., Otten, E., Pospischil, T., Potokar, M., Rohe, D., Schmieden, H., Schmiedeskamp, J., Seimetz, M., Sick, I., Sirca, S., Skibinski, R., Testa, G., Walcher, T., Warren, G., Weis, M., Witala, H., Wohrle, H., and Zeier M.

Subjects
Neutron charge form factor, Final-state interaction, High Energy Physics::Experiment, Nuclear Experiment
Abstract

The charge form factor of the neutron has been determined from asymmetries measured in quasi-elastic 3He-pol.(e-pol., e'n) at a momentum transfer of 0.67(GeV/c)2. In addition, the target analysing power Ay0, has been measured to study effects of final state interactions and meson exchange currents.

Published
2003

14. Final state interaction effects in 3He-pol(e-pol, e'p)

Author

Carasco, C., Bermuth, J., Merle, P., Bartsch, P., Baumann, D., Bohm, R., Bosnar, Damir, Ding, M., Distler, M.O., Friedrich, J., Friedrich, J.M., Golak, J., Glockle, W., Hauger, M., Heil, W., Jennewein, P., Jourdan, J., Kamada, H., Klein, A., Kohl, M., Krygier, K.W., Merkel, H., Muller, U., Neuhausen, R., Nogga, A., Normand, C., Otten, E., Pospischil, T., Potokar, M., Rohe, D., Schmieden, H., Schmiedeskamp, J., Seimetz, M., Sick, I., Sirca, S., Skibinski, R., Testa, G., Walcher, T., Warren, G., Weis, M., Witala, H., and Wohrle, H.

Subjects
Polarized electron scattering, 3He-structure, Final-state interaction
Abstract

Asymmetries in quasi-elastic 3He-pol(e-pol, e'P)have been measured at a momentum transfer of 0.67 (GeV/c)2 and are compared to a calculation which takes into account relativistic kinematics in the final state and a relativistic one-body current operator. With an exact solution of the Faddeev equation for the 3He-ground state and an approximate treatment of final state interactions in the continuum good agreement is found with the experimental data.

Published
2003

15. Measurement of the beam helicity asymmetry in the p(e_pol), e' p)pi0 reaction at the energy of delta(1232) resonance

Author

Bartsch, P., Baumann, D., Bermuth, J., Bohm, R., Bohinc, K., Bosnar, Damir, Ding, M., Distler, M., Drechsel, D., Elsner, D., Ewald, I., Friedrich, J., Friedrich, J.M., Grozinger, S., Hedicke, S., Jennewein, P., Kahrau, M., Kamalov, S.S., Klein, F., Krygier, K.W., Liesenfeld, A., Merkel, H., Merle, P., Muller, U., Neuhausen, R., Pospischil, T., Potokar, M., Rosner, G., Schmieden, H., Seimetz, M., Sule, A., Tiator, L., Wagner, A., Walcher, T., and Weis M.

Subjects
Beam-helicity asymmetry, Delta particle, hadron models, Nuclear Experiment
Abstract

In a p(e_pol, e'p)pi_0 out-of-plane coincidence experiment at the 3-spectrometer setup of the Mainz Microtron MAMI, the beam-helicity asymmetry has been precisely measured around the energy of the Delta(1232) resonance and Q^2 = 0.2 (GeV/c)^2. The results are in disagreement with three up-to-date model calculations. This is interpreted as lack of understanding of the non-resonant background, which in dynamical models is related to the pion cloud.

Published
2002

16. Measurement of the beam-helicity asymmetry in the p(e_pol,e'p)pi_0 reaction at the energy of the Delta(1232) resonance

Author

Bartsch, P., Baumann, D., Bermuth, J., Boehm, R., Bohinc, K., Bosnar, D., Ding, M., Distler, M., Drechsel, D., Elsner, D., Ewald, I., Friedrich, J., Friedrich, J. M., Groezinger, S., Hedicke, S., Jennewein, P., Kahrau, M., Kamalov, S. S., Klein, F., Krygier, K. W., Liesenfeld, A., Merkel, H., Merle, P., Mueller, U., Neuhausen, R., Pospischil, Th., Potokar, M., Rosner, G., Schmieden, H., Seimetz, M., Suele, A., Tiator, L., Wagner, A., Walcher, Th., and Weis, M.

Subjects
FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

In a p(e_pol,e'p)pi_0 out-of-plane coincidence experiment at the 3-spectrometer setup of the Mainz Microtron MAMI, the beam-helicity asymmetry has been precisely measured around the energy of the Delta(1232) resonance and Q^2 = 0.2 (GeV/c)^2. The results are in disagreement with three up-to-date model calculations. This is interpreted as lack of understanding of the non-resonant background, which in dynamical models is related to the pion cloud., 5 pages, 2 figures, 2 tables

Published
2001

17. Neutral pion threshold production at Q^2=0.05 GeV^2/c^2 and Chiral Perturbation Theory

Author

Merkel, Harald, Bartsch, Peter, Baumann, Dagmar, Bermuth, J��rg, Bernstein, Aron M., Bohinc, Klemen, B��hm, Ralph, Clawiter, Norbert, Derber, Sabine, Ding, Matthias, Distler, Michael O., Ewald, Ingo, Friedrich, Jan M., Friedrich, J��rg, Jennewein, Peter, Kahrau, Marco, Kohl, Michael, Krygier, Klaus Werner, Kuss, Michael, Liesenfeld, Arnd, Merle, Pascal, Miskimen, Rory A., M��ller, Ulrich, Neuhausen, Reiner, Pavan, Marcello M., Pospischil, Thomas, Potokar, Milan, Rosner, G��nther, Schmieden, Hartmut, Seimetz, Michael, ��irca, Simon, Wagner, Axel, Walcher, Thomas, and Weis, Markus

Subjects
FOS: Physical sciences, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

New data are presented on the p(e,e'p)\pi^0 reaction at threshold at a four-momentum transfer of Q^2=0.05 GeV^2/c^2. The data were taken with the three-spectrometer setup of the A1 Collaboration at the Mainz Microtron MAMI. The complete center of mass solid angle was covered up to a center of mass energy of 4 MeV above threshold. Combined with measurements at three different values of the virtual photon polarization \epsilon, the structure functions \sigma_T, \sigma_L, \sigma_{TT}, and \sigma_{TL} are determined. The results are compared with calculations in Heavy Baryon Chiral Perturbation Theory and with a phenomenological model. The measured cross section is significantly smaller than both predictions., Comment: 4 pages, 3 Postscript figures, latex2e, v2 minor changes

Published
2001

18. Measurement of the recoil polarization in the p(e, e'p)π0 reaction at the Δ(1232) resonance

Author

Pospischil, T.H., Bartsch, P., Baumann, D., Bermuth, J., Bohm, R., Bohinc, K., Derber, S., Ding, M., Distler, M., Drechsel, D., Elsner, D., Ewald, I., Friedrich, J., Friedrich, J.M., Geiges, R., Hedicke, S., Jennewein, P., Kahrau, M., Kamalov, S.S., Klein, F., Krygier, K.W., Lac, J., Liesenfeld, A., McIntyre, J., Merkel, H., Merle, P., Muller, U., Neuhausen, R., Potokar, M., Ransome, R.D., Rohe, D., Rosner, G., Schmieden, H., Seimetz, M., Sirca, S., Sick, I., Sule, A., Tiator, L., Wagner, A., Walcher, T., Warren, G.A., and Weis, M.

Subjects
QC
Abstract

The recoil proton polarization in the reaction P(e, elp)φ0 at the energy of the [Triangle Open] (1232) resonance was measured. Because of the spin precession in the magnetic spectrometer all three polarization components Px, Py, and Pz were simultaneously accessible. From Px the Coulomb quadrupole to magnetic dipole ratio was determined in the framework of the Mainz Unitary Isobar Model as colossal magnetoresistance (CMR)(Q2 = 0.121 GeV) = (-6.4 ± 0.7stat ± 0.8syst)%, which is in good agreement with the result obtained from the polarization ratio Px/Pz.

Published
2001

19. Polarization transfer in the $^{4}$He$(\vec{e},e' \vec{p}^{3}$H reaction

Author

Dieterich, S., Bartsch, P., Baumann, D., Bermuth, J., Bohinc, K., B��hm, R., Bosnar, D., Derber, S., Ding, M., Distler, M., Ewald, I., Friedrich, J., Friedrich, J. M., Gilman, R., Glashausser, C., Hauger, M., Jennewein, P., Jourdan, J., Kelly, J. J., Kohl, M., Kozlov, A., Krygier, K. W., Kumbartzki, G., Lac, J., Liesenfeld, A., Merkel, H., M��ller, U., Neuhausen, R., Pospischil, Th., Ransome, R. D., Rohe, D., Rosner, G., Schmieden, H., Seimetz, M., Sick, I., Strauch, S., Udias, J. M., Vignote, J. R., Wagner, A., Walcher, Th., Warren, G., and Weis, M.

Subjects
Nuclear Theory, FOS: Physical sciences, Physics::Accelerator Physics, Nuclear Experiment (nucl-ex), Nuclear Experiment
Abstract

Polarization transfer in the 4He(e,e'p)3H reaction at a Q^2 of 0.4 (GeV/c)^2 was measured at the Mainz Microtron MAMI. The ratio of the transverse to the longitudinal polarization components of the ejected protons was compared with the same ratio for elastic ep scattering. The results are consistent with a recent fully relativistic calculation which includes a predicted medium modification of the proton form factor based on a quark-meson coupling model., 5 pages, Latex, 2 postscript figures, submitted to Physics Letters B

Published
2000

20. Measurement of the recoil polarization in the p (\vec e, e' \vec p) pi^0 reaction at the \Delta(1232) resonance

Author

Pospischil, Th., Bartsch, P., Baumann, D., Bermuth, J., Boehm, R., Bohinc, K., Derber, S., Ding, M., Distler, M., Drechsel, D., Elsner, D., Ewald, I., Friedrich, J., Friedrich, J. M., Geiges, R., Hedicke, S., Jennewein, P., Kahrau, M., Kamalov, S. S., Klein, F., Krygier, K. W., Lac, J., Liesenfeld, A., McIntyre, J., Merkel, H., Merle, P., Mueller, U., Neuhausen, R., Potokar, M., Ransome, R. D., Rohe, D., Rosner, G., Schmieden, H., Seimetz, M., Sirca, S., Sick, I., Suele, A., Tiator, L., Wagner, A., Walcher, Th, Warren, G. A., and Weis, M.

Subjects
Nuclear Experiment
Abstract

The recoil proton polarization has been measured in the p (\vec e,e'\vec p) pi^0 reaction in parallel kinematics around W = 1232 MeV, Q^2 = 0.121 (GeV/c)^2 and epsilon = 0.718 using the polarized c.w. electron beam of the Mainz Microtron. Due to the spin precession in a magnetic spectrometer, all three proton polarization components P_x/P_e = (-11.4 \pm 1.3 \pm 1.4) %, P_y = (-43.1 \pm 1.3 \pm 2.2) %, and P_z/P_e = (56.2 \pm 1.5 \pm 2.6) % could be measured simultaneously. The Coulomb quadrupole to magnetic dipole ratio CMR = (-6.4\pm 0.7_{stat}\pm 0.8_{syst}) % was determined from P_x in the framework of the Mainz Unitary Isobar Model. The consistency among the reduced polarizations and the extraction of the ratio of longitudinal to transverse response is discussed., Comment: 5 pages LaTeX, 1 table, 2 eps figures

Published
2000

21. Measurement of the electric neutron form factor G[sub en] in the exclusive reaction [sup 3]Hvector e(evector ,e[sup ′]n) at momentum transfer Q[sup 2]=0.67 (GeV/c)[sup 2].

Author

Bermuth, J.

Subjects
*FORM factor (Nuclear physics), *NEUTRONS, *MOMENTUM transfer
Abstract

The experiment to measure Gen in the quasielastic reaction [sup 3]He(e, e' n) at fourmomentum transfer Q² = 0.67 (GeV/c)² has been continued in June 2000. The asymmetry with respect to reversal of the electron helicity has been measured both for perpendicular and for parallel orientation of the [sup 3]He spin with respect to q. From the asymmetry ratio we finally obtained G[sub en] = 0 0468 amp; 0.0064[sub syst] ± 0.0027[sub stat]. In addition, the asymmetry A[sup 0, sub y] with the target spin normal to the scattering plane and the electrons unpolarized, has been measured in the reaction [sup 3]He(e,e'p(n)). A[sup 0, sub y] is a direct observable of FSI and MEC effects. It allows to check theoretical predictions. Thereby one gains redundancies in the attempt to derive single particle properties of the free neutrons from measurement on bound neutrons, and one can verify whether [sup 3]He can be used as an effective polarized neutron target. [ABSTRACT FROM AUTHOR]

Published
2001

22. Polarized high pressure 3Hvector e target at MAMI.

Author

Rohe, Daniela, Bartsch, P., Baumann, D., Becker, J., Bermuth, J., de Bever, L. J., Böhm, R., Buttazoni, S., Caprano, T., Clawiter, N., Deninger, A., Derber, S., Ding, M., Distler, M., Ebbes, A., Ebert, M., Ewald, I., Friedrich, J., Friedrich, J. M., and Geiges, R.

Published
1998
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25. 3He( e, e′ pp) and 3He( e, e′ pn) reactions at AmPS and MAMI.

Author

Middleton, D. G., Annand, J. R. M., Ases Antelo, M., Ayerbe, C., Barneo, P., Baumann, D., Bermuth, J., Bernauer, J., Blok, H. P., Böhm, R., Bosnar, D., Ding, M., Distler, M. O., Friedrich, J., García Llongo, J., Glazier, D. I., Grabmayr, P., Hehl, T., Heim, J., and Hesselink, W. H. A.

Subjects
MEASUREMENT, NUCLEAR reactions, COLLISIONS (Nuclear physics), PARTICLES (Nuclear physics), NUCLEAR physics, MATHEMATICAL analysis
Abstract

This paper reports on measurements of the 3He( e, e′ pp) reaction measured at AmPS and the 3He( e, e′ pn) reaction measured at MAMI. The measurements were performed in similar kinematics to allow a comparison to be made between the cross sections of the two reactions. Results are shown for both reactions together with a comparison for the 3He( e, e′ pp) data with continuum Faddeev calculations. [ABSTRACT FROM AUTHOR]

Published
2008
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26. Separated cross-sections in πelectroproduction at threshold at Q2 = 0.05GeV2/c2.

Author

Weis, M., Bartsch, P., Baumann, D., Bermuth, J., Bernstein, A. M., Bohinc, K., Böhm, R., Ding, M., Distler, M. O., Ewald, I., Friedrich, J. M., Kahrau, M., Kohl, M., Krygier, K. W., Liesenfeld, A., Merkel, H., Merle, P., Müller, U., Neuhausen, R., and Pavan, M. M.

Subjects
PARTICLES (Nuclear physics), PROTONS, CENTER of mass, PHOTONS, BARYONS, MATHEMATICAL models
Abstract

The differential cross-sections σ0 = σT + εσL , σLT , and σTT of π0 electroproduction from the proton were measured from threshold up to an additional center-of-mass energy of 40MeV, at a value of the photon four-momentum transfer of Q 2 = 0.05 GeV2/c2 and a center-of-mass angle of θ = 90° . By an additional out-of-plane measurement with polarized electrons σLT' was determined. This showed for the first time the presence of an imaginary part of the s -wave above the π+ threshold, which is usually interpreted as a unitary cusp. The predictions of the Heavy Baryon Chiral Perturbation Theory (HBChPT) are in disagreement with these data. On the other hand, the data are somewhat better predicted by the MAID phenomenological model and are in good agreement with the dynamical model DMT. [ABSTRACT FROM AUTHOR]

Published
2008
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27. Measurement of the electric form factor of the neutron at Q2 = 0.3-0.8 (GeV/ c)2a.

Author

Glazier, D.I., Seimetz, M., Annand, J.R.M., Arenhövel, H., Ases Antelo, M., Ayerbe, C., Bartsch, P., Baumann, D., Bermuth, J., Böhm, R., Bosnar, D., Ding, M., Distler, M.O., Elsner, D., Friedrich, J., Hedicke, S., Jennewein, P., Mañnas, G. Jover, Klein, F.H., and Kohl, M.

Subjects
APPROXIMATION theory, SCATTERING (Physics), PARTICLES (Nuclear physics), ELLIPSOMETRY, OPTICAL measurements, OPTICAL polarization
Abstract

The electric form factor of the neutron, GE,n, has been measured at the Mainz Microtron by recoil polarimetry in the quasielasticD(¯e,e’¯n)preaction. Three data points have been extracted at squared four-momentum transfersQ2 = 0.3, 0.6 and 0.8 (GeV/c)2. Corrections for nuclear binding effects have been applied. [ABSTRACT FROM AUTHOR]

Published
2005
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28. The neutron charge form factor and target analyzing powers from <f>3<ovl type="rarr" STYLE="S">He</ovl>(e→,e′n)</f> scattering

Author

Bermuth, J., Merle, P., Carasco, C., Baumann, D., Böhm, R., Bosnar, D., Ding, M., Distler, M.O., Friedrich, J., Friedrich, J.M., Golak, J., Glöckle, W., Hauger, M., Heil, W., Jennewein, P., Jourdan, J., Kamada, H., Klein, A., Kohl, M., and Krusche, B.

Subjects
*NEUTRONS, *QUASIELASTIC light scattering
Abstract

The charge form factor of the neutron has been determined from asymmetries measured in quasi-elastic 3He(e→,e′n) at a momentum transfer of 0.67 (GeV/c)2. In addition, the target analyzing power, Ayo, has been measured to study effects of final state interactions and meson exchange currents. [Copyright &y& Elsevier]

Published
2003
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29. Final state interaction effects in 3(e→,e′p).

Author

Carasco, C., Bermuth, J., Merle, P., Bartsch, P., Baumann, D., Böhm, R., Bosnar, D., Ding, M., Distler, M. O., Friedrich, J., Friedrich, J. M., Golak, J., Glöckle, W., Hauger, M., Heil, W., Jennewein, P., Jourdan, J., Kamada, H., Klein, A., and Kohl, M.

Subjects
*MOMENTUM transfer, *KINEMATICS
Abstract

Asymmetries in quasi-elastic 3(e→,e′p) have been measured at a momentum transfer of 0.67 (GeV/c)2 and are compared to a calculation which takes into account relativistic kinematics in the final state and a relativistic one-body current operator. With an exact solution of the Faddeev equation for the 3He-ground state and an approximate treatment of final state interactions in the continuum good agreement is found with the experimental data. [Copyright &y& Elsevier]

Published
2003
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31. Evidence for narrow Δ0(1232) states in the 12 C( e, e' pπ−}11 C Reaction.

Author

Bartsch, P., Baumann, D., Bermuth, J., Bohinc, K., Böhm, R., Bosnar, D., Clawiter, N., Derber, S., Ding, M., Distler, M.O., Ebbes, A., Ewald, I., Friedrich, J.M., Friedrich, J., Jennewein, P., Kahrau, M., Kohl, M., Kozlov, A., Krygier, K.W., and Kuss, M.

Abstract

The reaction 12C(e,e'Δ0)11C →12C(e,e'pπ−)11C was investigated at the Mainz Microtron MAMI in a triple coincidence measurement using the three spectrometer setup of the A1 Collaboration. The good missing mass resolution of σm= 0.27 MeV/c2 allowed to select the events belonging to the ground state of 11C. Cutting on these events the excitation energy spectra of 12CΔ0 show evidence for two peaks of about 4 MeV width (FWHM) at 282 MeV and 296 MeV with a significance of about 4.5 standard deviations. The peaks are interpreted in a simple weak coupling model as bound Δ0 states in 12CΔ0. [ABSTRACT FROM AUTHOR]

Published
1999
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32. Rapid communication Photoemission of spinpolarized electrons from strained GaAsP.

Author

Drescher, P., Andresen, H. G., Aulenbacher, K., Bermuth, J., Dombo, T., Fischer, H., Euteneuer, H., Faleev, N. N., Galaktionov, M. S., von Harrach, D., Hartmann, P., Hoffmann, J., Jennewein, P., Kaiser, K. H., Köbis, S., Kovalenkov, O. V., Kreidel, H. J., Langbein, J., Mamaev, Y. A., and Nachtigall, Ch.

Subjects
PHOTOEMISSION, ELECTRONS, GALLIUM arsenide
Abstract

Strained layer GaAs[sub .95]P[sub .05] photo cathodes are presented, which emit electron beams spinpolarized to a degree of P = 75% typically. Quantum yields around QE = 0.4% are observed routinely. The figure of merit P² × QE = 2.3 × 10[sup -3] is comparable to that of the best strained layer cathodes reported in literature. The optimum wavelength of irradiating light around 830 nm is in convenient reach of Ti:sapphire lasers or diode lasers respectively. The cathodes are produced using MOCVD-techniques. A GaAs[sub .55]P[sub .45]GaAs[sub .85]P[sub .15] superlattice structure prevents the migration of dislocations from the substrate and bottom layers to the strained overlayer. The surface is protected by an arsenic layer so that no chemical cleaning is necessary before installation into vacuum. The source of polarized electrons attached to the Mainz race track microtron MAMI works with such cathodes now. More than 1000 hours beamtime have been performed successfully. [ABSTRACT FROM AUTHOR]

Published
1996
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33. First measurements of the 16O(e, e'pn)14N reaction.

Author

Middleton, D. G., Annand, J. R. M., Barbieri, C., Barneo, P., Bartsch, P., Baumann, D., Bermuth, J., Bosnar, D., Blok, H. P., Böhm, R., Ding, M., Distler, M. O., Elsner, D., Friedrich, J., Giusti, C., Glazier, D. I., Grabmayr, P., Grözinger, S., Hehl, T., and Heim, J.

Subjects
AUTHORS
Abstract

A correction to the article titled "First measurements of the 16O(e; e0pn)14N reaction" published in the 2006 issue of the European Physical Journal is presented.

Published
2006
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34. The MAMI source of polarized electrons

Author

Aulenbacher, K, Nachtigall, Ch, Andresen, H.G, Bermuth, J, Dombo, Th, Drescher, P, Euteneuer, H, Fischer, H, Harrach, D.v, Hartmann, P, Hoffmann, J, Jennewein, P, Kaiser, K.H, Köbis, S, Kreidel, H.J, Langbein, J, Petri, M, Plützer, S, Reichert, E, Schemies, M, Schöpe, H.-J, Steffens, K.-H, Steigerwald, M, Trautner, H, and Weis, Th

Published
1997
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35. Picosecond polarized electron bunches from a strained layer GaAsP photocathode

Author

Hartmann, P., Bermuth, J., Hoffmann, J., Köbis, S., Reichert, E., Andresen, H.G., Aulenbacher, K., Drescher, P., Euteneuer, H., Fischer, H., Jennewein, P., Kaiser, K.-H., Kreidel, H.J., Nachtigall, Ch., Plützer, S., Schemies, M., Steffens, K.-H., Steigerwald, M., Trautner, H., Harrach, D.v., Altarev, I., Geiges, R., Grimm, K., Hammel, Th., Heinen-Konschak, E., Hofmann, H., Kabuß, E.-M., Lopes-Ginja, A., Maas, F.E., and Schilling, E.

Published
1996
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37. Self energies of the pion and the Δ isobar from the 3He(e,e′π+)3H reaction.

Author

Kohl, M., Bartsch, P., Baumann, D., Bermuth, J., Böhm, R., Bohinc, K., Derber, S., Ding, M., Distler, M.O., Ewald, I., Friedrich, J., Friedrich, J. M., Jennewein, P., Kahrau, M., Kamalov, S. S., Kozlov, A., Krygier, K. W., Kuss, M., Liesenfeld, A., and Merkel, H.

Subjects
*PIONS, *RESONANCE
Abstract

In a kinematically complete experiment at the Mainz microtron MAMI, pion angular distributions of the 3He(e,e′π+)3H reaction have been measured in the excitation region of the Δ resonance to determine the longitudinal (L), transverse (T), and the LT interference part of the differential cross section. The data are described only after introducing self-energy modifications of the pion and Δ-isobar propagators. Using Chiral Perturbation Theory (ChPT) to extrapolate the pion self energy as inferred from the measurement on the mass shell, we deduce a reduction of the π+ mass of Δmπ+ =–1.7+1.7–2.1 MeV/c2 in the neutron-rich nuclear medium at a density of 𝜌=0.057+0.085–0.057 fm–3.Our data are consistent with the Δ self energy determined from measurements of π0 photoproduction from 4He and heavier nuclei. [Copyright &y& Elsevier]

Published
2002
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38. Measurement of the beam-helicity asymmetry in the p((-->)e,e'p)pi(0) reaction at the energy of the Delta(1232) resonance.

Author

Bartsch P, Baumann D, Bermuth J, Böhm R, Bohinc K, Bosnar D, Ding M, Distler M, Drechsel D, Elsner D, Ewald I, Friedrich J, Friedrich JM, Grözinger S, Hedicke S, Jennewein P, Kahrau M, Kamalov SS, Klein F, Krygier KW, Liesenfeld A, Merkel H, Merle P, Müller U, Neuhausen R, Pospischil T, Potokar M, Rosner G, Schmieden H, Seimetz M, Süle A, Tiator L, Wagner A, Walcher T, and Weis M

Abstract

In a p((-->)e,e'p)pi(0) out-of-plane coincidence experiment at the three-spectrometer setup of the Mainz Microtron MAMI, the beam-helicity asymmetry has been precisely measured around the energy of the Delta(1232) resonance and Q(2) = 0.2(GeV/c)(2). The results are in disagreement with three up-to-date model calculations. This is interpreted as a lack of understanding of the nonresonant background, which in dynamical models is related to the pion cloud.

Published
2002
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39. Neutral pion threshold production at Q(2) = 0.05 GeV(2)/c(2) and chiral perturbation theory.

Author

Merkel H, Bartsch P, Baumann D, Bermuth J, Bernstein AM, Bohinc K, Böhm R, Clawiter N, Derber S, Ding M, Distler MO, Ewald I, Friedrich JM, Friedrich J, Jennewein P, Kahrau M, Kohl M, Krygier KW, Kuss M, Liesenfeld A, Merle P, Miskimen RA, Müller U, Neuhausen R, Pavan MM, Pospischil T, Potokar M, Rosner G, Schmieden H, Seimetz M, Sirca S, Wagner A, Walcher T, and Weis M

Abstract

New data are presented on the p(e,e'p)pi(0) reaction at threshold at a four-momentum transfer of Q(2) = 0.05 GeV(2)/c(2). The data were taken with the three-spectrometer setup of the A1 Collaboration at the Mainz Microtron MAMI. The complete center of mass solid angle was covered up to a center of mass energy of 4 MeV above threshold. Combined with measurements at three different values of the virtual photon polarization epsilon, the structure functions sigma(T), sigma(L), sigma(TT), and sigma(TL) are determined. The results are compared with calculations in heavy baryon chiral perturbation theory and with a phenomenological model. The measured cross section is significantly smaller than both predictions.

Published
2002
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40. Assessment of a single-acquisition imaging sequence for oxygen-sensitive (3)He-MRI.

Author

Deninger AJ, Eberle B, Bermuth J, Escat B, Markstaller K, Schmiedeskamp J, Schreiber WG, Surkau R, Otten E, and Kauczor HU

Subjects
Computer Simulation, Helium, Humans, Image Processing, Computer-Assisted, Isotopes, Monte Carlo Method, Oxygen, Partial Pressure, Pulmonary Ventilation physiology, Lung anatomy & histology, Magnetic Resonance Imaging
Abstract

MRI of the lungs using hyperpolarized helium-3 ((3)He) allows the determination of intrapulmonary oxygen partial pressures (p(O2)). The need to separate competing processes of signal loss has hitherto required two different imaging series during two different breathing maneuvers. In this work, a new imaging strategy to measure p(O2) by a single series of consecutive scans is presented. The feasibility of the method is demonstrated in three healthy human volunteers. Maps and histograms of intrapulmonary p(O2) are calculated. Changes in the oxygen concentration of the inhaled gas mixture are well reproduced in the histograms. Monte Carlo (MC) simulations of the temporal evolution of (3)He hyperpolarization within the lungs were performed to evaluate the accuracy of this measurement technique, and its limitations., (Copyright 2002 Wiley-Liss, Inc.)

Published
2002
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41. Measurement of the recoil polarization in the p(e-->, e'p-->)pi(0) reaction at the Delta(1232) resonance.

Author

Pospischil T, Bartsch P, Baumann D, Bermuth J, Böhm R, Bohinc K, Derber S, Ding M, Distler M, Drechsel D, Elsner D, Ewald I, Friedrich J, Friedrich JM, Geiges R, Hedicke S, Jennewein P, Kahrau M, Kamalov SS, Klein F, Krygier KW, Lac J, Liesenfeld A, McIntyre J, Merkel H, Merle P, Müller U, Neuhausen R, Potokar M, Ransome RD, Rohe D, Rosner G, Schmieden H, Seimetz M, Sirca S, Sick I, Süle A, Tiator L, Wagner A, Walcher T, Warren GA, and Weis M

Abstract

The recoil proton polarization has been measured in the p(e-->,e'p-->)pi(0) reaction in parallel kinematics around W = 1232 MeV, Q2 = 0.121 (GeV/c)2, and epsilon = 0.718 using the polarized cw electron beam of the Mainz Microtron. All three proton polarization components, Px/P(e) = (-11.4+/-1.3+/-1.4)%, P(y) = (-43.1+/-1.3+/-2.2)%, and P(z)/P(e) = (56.2+/-1.5+/-2.6)%, could be measured simultaneously. The Coulomb quadrupole to magnetic dipole ratio, CMR = (-6.4+/-0.7(stat)+/-0.8(syst))%, was determined from Px in the framework of the Mainz Unitary Isobar Model. The consistency among the reduced polarizations and the extraction of the ratio of longitudinal-to-transverse response is discussed.

Published
2001
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