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12 results on '"Bogendoerfer, R."'

1. Photoproduction of $\omega$ mesons on nuclei near the production threshold

Author

Nanova, M., Weil, J., Friedrich, S., Metag, V., Mosel, U., Anton, G., Bacelar, J. C. S., Bartholomy, O., Bayadilov, D., Beloglazov, Y. A., Bogendörfer, R., Castelijns, R., Crede, V., Dutz, H., Ehmanns, A., Elsner, D., Essig, K., Ewald, R., Fabry, I., Fuchs, M., Funke, Ch., Gothe, R., Gregor, R., Gridnev, A. B., Gutz, E., Höffgen, S., Hoffmeister, P., Horn, I., Hössl, J., Jaegle, I., Junkersfeld, J., Kalinowsky, H., Klein, Frank, Klein, Friedrich, Klempt, E., Konrad, M., Kopf, B., Kotulla, M., Krusche, B., Langheinrich, J., Löhner, H., Lopatin, I. V., Lotz, J., Lugert, S., Menze, D., Mertens, T., Messchendorp, J. G., Morales, C., Novotny, R., Ostrick, M., Pant, L. M., van Pee, H., Pfeiffer, M., Roy, A., Radkov, A., Schadmand, S., Schmidt, Ch., Schmieden, H., Schoch, B., Shende, S., Suft, G., Süle, A., Sumachev, V. V., Szczepanek, T., Thoma, U., Trnka, D., Varma, R., Walther, D., Weinheimer, Ch., and Wendel, Ch.

Subjects
Nuclear Experiment
Abstract

The photoproduction of $\omega$ mesons on LH_2, C and Nb has been studied for incident photon energies from 900 to 1300 MeV using the CB/TAPS detector at ELSA. The $\omega$ line shape does not show any significant difference between the LH_2 and the Nb targets. The data are compared with results of transport calculations that predict a sensitivity of the $\omega$ line shape to in-medium modifications near the production threshold on a free nucleon of $E_{\gamma}^{lab}$ = 1109 MeV.}, Comment: 5 pages, 3 figures

Published
2010
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2. In-medium $\omega$ mass from the $\gamma + Nb \to \pi^{0}\gamma + X$ reaction

Author

Collaboration, The The CBELSA/TAPS, Nanova, M., Metag, V., Anton, G., Bacelar, J. C. S., Bartholomy, O., Bayadilov, D., Beloglazov, Y. A., Bogendörfer, R., Castelijns, R., Crede, V., Dutz, H., Ehmanns, A., Elsner, D., Essig, K., Ewald, R., Fabry, I., Fuchs, M., Funke, Ch., Gothe, R., Gregor, R., Gridnev, A. B., Gutz, E., Höffgen, S., Hoffmeister, P., Horn, I., Hössl, J., Jaegle, I., Junkersfeld, J., Kalinowsky, H., Klein, Frank, Klein, Friedrich, Klempt, E., Konrad, M., Kopf, B., Kotulla, M., Krusche, B., Langheinrich, J., Löhner, H., Lopatin, I. V., Lotz, J., Lugert, S., Menze, D., Mertens, T., Messchendorp, J. G., Morales, C., Novotny, R., Ostrick, M., Pant, L. M., van Pee, H., Pfeiffer, M., Roy, A., Radkov, A., Schadmand, S., Schmidt, Ch., Schmieden, H., Schoch, B., Shende, S., Suft, G., Süle, A., Sumachev, V. V., Szczepanek, T., Thoma, U., Trnka, D., Varma, R., Walther, D., Weinheimer, Ch., and Wendel, Ch.

Subjects
Nuclear Experiment
Abstract

Data on the photoproduction of $\omega$ mesons on nuclei have been re-analyzed in a search for in-medium modifications. The data were taken with the Crystal Barrel(CB)/TAPS detector system at the ELSA accelerator facility in Bonn. First results from the analysis of the data set were published by D. Trnka et al. in Phys. Rev. Lett 94 (2005) 192303 \cite{david}, claiming a lowering of the $\omega$ mass in the nuclear medium by 14$%$ at normal nuclear matter density. The extracted $\omega$ line shape was found to be sensitive to the background subtraction. For this reason a re-analysis of the same data set has been initiated and a new method has been developed to reduce the background and to determine the shape and absolute magnitude of the background directly from the data. Details of the re-analysis and of the background determination are described. The $\omega$ signal on the $Nb$ target, extracted in the re-analysis, does not show a deviation from the corresponding line shape on a $LH_2$ target, measured as reference. The earlier claim of an in-medium mass shift is thus not confirmed. The sensitivity of the $\omega$ line shape to different in-medium modification scenarios is discussed., Comment: 13 pages and 11 figures, submitted for publication

Published
2010
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3. Modification of the $\omega$-Meson Lifetime in Nuclear Matter

Author

Kotulla, M., Trnka, D., Mühlich, P., Anton, G., Bacelar, J. C. S., Bartholomy, O., Bayadilov, D., Beloglazov, Y. A., Bogendörfer, R., Castelijns, R., Crede, V., Dutz, H., Ehmanns, A., Elsner, D., Ewald, R., Fabry, I., Fuchs, M., Essig, K., Funke, Ch., Gothe, R., Gregor, R., Gridnev, A. B., Gutz, E., Höffgen, S., Hoffmeister, P., Horn, I., Hössl, J., Jaegle, I., Junkersfeld, J., Kalinowsky, H., Klein, Frank, Klein, Fritz, Klempt, E., Konrad, M., Kopf, B., Krusche, B., Langheinrich, J., Löhner, H., Lopatin, I. V., Lotz, J., Lugert, S., Menze, D., Messchendorp, J. G., Mertens, T., Metag, V., Mosel, U., Nanova, M., Novotny, R., Ostrick, M., Pant, L. M., van Pee, H., Pfeiffer, M., Roy, A., Radkov, A., Schadmand, S., Schmidt, Ch., Schmieden, H., Schoch, B., Shende, S., Suft, G., Sumachev, V. V., Szczepanek, T., Süle, A., Thoma, U., Varma, R., Walther, D., Weinheimer, Ch., and Wendel, Ch.

Subjects
Nuclear Experiment, High Energy Physics - Phenomenology, Nuclear Theory
Abstract

The photo production of $\omega$ mesons on the nuclei C, Ca, Nb and Pb has been measured using the Crystal Barrel/TAPS detector at the ELSA tagged photon facility in Bonn. The dependence of the $\omega$ meson cross section on the nuclear mass number has been compared with three different types of models, a Glauber analysis, a BUU analysis of the Giessen theory group and a calculation by the Valencia theory group. In all three cases, the inelastic $\omega$ width is found to be $130-150 \rm{MeV/c^2}$ at normal nuclear matter density for an average 3-momentum of 1.1 GeV/c. In the restframe of the $\omega$ meson, this inelastic $\omega$ width corresponds to a reduction of the $\omega$ lifetime by a factor $\approx 30$. For the first time, the momentum dependent $\omega$N cross section has been extracted from the experiment and is in the range of 70 mb., Comment: 5 pages, 4 figures

Published
2008
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5. In-medium omega mass from the gamma+Nb -> pi(0)gamma+X reaction

Author

Nanova, M., Metag, V., Anton, G., Bacelar, J. C. S., Bartholomy, O., Bayadilov, D., Beloglazov, Y. A., Bogendoerfer, R., Castelijns, R., Crede, V., Dutz, H., Ehmanns, A., Elsner, D., Essig, K., Ewald, R., Fabry, I., Fuchs, M., Funke, Ch., Gothe, R., Gregor, R., Gridnev, A. B., Gutz, E., Hoeffgen, S., Hoffmeister, P., Horn, I., Hoessl, J., Jaegle, I., Junkersfeld, J., Kalinowsky, H., Klein, Frank, Klein, Friedrich, Klempt, E., Konrad, M., Kopf, B., Kotulla, M., Krusche, B., Langheinrich, J., Löhner, Herbert, Lopatin, I. V., Lotz, J., Lugert, S., Menze, D., Mertens, T., Messchendorp, J. G., Morales, C., Novotny, R., Ostrick, M., Pant, L. M., Schadmand, S., Shende, S., KVI - Center for Advanced Radiation Technology, and Research unit Nuclear & Hadron Physics

Subjects
TAPS, NUCLEI, ENERGIES, HADRONS, PHOTOPRODUCTION, SPECTROMETER, Nuclear Experiment, ELSA, ASYMPTOTIC FREEDOM
Abstract

Data on the photoproduction of omega mesons on nuclei have been reanalyzed in a search for in-medium modifications. The data were taken with the crystal barrel (CB)/two-arm photon spectrometer (TAPS) detector system at the ELectron Stretcher Anlage (ELSA) accelerator facility in Bonn. First results from the analysis of the data set were published by Trnka et al. [Phys. Rev. Lett. 94, 192303 (2005)], claiming a lowering of the. mass in the nuclear medium by 14% at normal nuclear matter density. The extracted. line shape was found to be sensitive to the background subtraction. For this reason a reanalysis of the same data set has been initiated, and a new method has been developed to reduce the background and to determine the shape and absolute magnitude of the background directly from the data. Details of the reanalysis and of the background determination are described. The omega signal on the Nb target, extracted in the reanalysis, does not show a deviation from the corresponding line shape on a LH2 target, measured as reference. The earlier claim of an in-medium mass shift is thus not confirmed. The sensitivity of the omega line shape to different in-medium modification scenarios is discussed.

Published
2010

6. Evidence for a Parity Doublet Delta(1920)P-33 and Delta(1940)D-33 from gamma p -> p pi(0)eta

Author

Horn, I., Anisovich, A. V., Anton, G., Bantes, R., Bartholomy, O., Beck, R., Beloglazov, Yu., Bogendoerfer, R., Castelijns, R., Crede, V., Ehmanns, A., Ernst, J., Fabry, I., Flemming, H., Foesel, A., Fuchs, M., Funke, Chr., Gothe, R., Gridnev, A., Gutz, E., Hoeffgen, St., Hoessl, J., Junkersfeld, J., Kalinowsky, H., Klein, F., Klempt, E., Koch, H., Konrad, M., Kopf, B., Krusche, B., Langheinrich, J., Loehner, H., Lopatin, I., Lotz, J., Matthaey, H., Menze, D., Messchendorp, J., Metag, V., Nikonov, V. A., Novinski, D., Ostrick, M., van Pee, H., Sarantsev, A. V., Schmidt, C., Schmieden, H., Schoch, B., Suft, G., Sumachev, V., Szczepanek, T., Thoma, U., and KVI - Center for Advanced Radiation Technology

Subjects
BARYON RESONANCES, PHOTOPRODUCTION, Nuclear Experiment, ELSA, DECAYS, RESTORATION
Abstract

Evidence is reported for the existence of a parity doublet of Delta resonances with total angular momentum J=3/2 from photoproduction of the p pi(0)eta final state. The two parity partners Delta(1920)P-33 and Delta(1940)D-33 make significant contributions to the reaction. Cascades of resonances into Delta(1232)eta, N(1535)pi, and Na-0(980) are clearly observed.

Published
2008

7. Study of the reaction gamma p -> p pi(0)eta

Author

Horn, I., Anisovich, A. V., Anton, G., Bantes, R., Bartholomy, O., Beck, R., Beloglazov, Y., Bogendoerfer, R., Castelijns, R., Crede, V., Ehmanns, A., Ernst, J., Fabry, I., Flemming, H., Foesel, A., Fuchs, M., Funke, Ch., Gothe, R., Gridnev, A., Gutz, E., Hoeffgen, S., Hoessi, J., Junkersfeld, J., Kalinowsky, H., Klein, F., Klempt, E., Koch, H., Konrad, M., Kopf, B., Krusche, B., Langheinrich, J., Loehner, H., Lopatin, I., Lotz, J., Matthaey, H., Menze, D., Messchendorp, J., Metag, V., Nikonov, V. A., Novinski, D., Ostrick, M., van Pee, H., Sarantsev, A. V., Schmidt, C., Schmieden, H., Schoch, B., Suft, G., Sumachev, V., Szczepanek, T., Thoma, U., Walther, D., Weinheimer, Ch., and KVI - Center for Advanced Radiation Technology

Subjects
CHIRAL-SYMMETRY, RELATIVISTIC QUARK-MODEL, PHOTON ENERGIES, STRANGE-BARYON SPECTRUM, BEAM ASYMMETRY, PHOTOPRODUCTION, PARITY DOUBLETS, RESONANCE, OPERATOR EXPANSION METHOD, PARTIAL-WAVE
Abstract

The reaction gamma p -> p pi(0)eta has been studied with the CBELSA detector at the tagged photon beam of the Bonn electron stretcher facility. The reaction shows contributions from Delta(+)(1232)eta, N(1535)(+) pi(0) and pa(0)(980) as intermediate states. A partial-wave analysis suggests that the reaction proceeds via formation of six Delta-resonances, Delta(1600)P-33, Delta(1920)P-33, Delta(1700)D-33, Delta(1940)D-33, Delta(1905)F-35, Delta(2360)D-33, and two nucleon resonances N(1880)P-11 and N(2200)P-13, for which pole positions and decay branching ratios are given.

Published
2008

8. Photoproduction of π 0 ω off protons for E γ ≤3 GeV

Author

Junkersfeld, J., Anisovich, A. V., Anton, G., Bantes, R., Bartholomy, O., Beck, R., Beloglazov, Yu, Bogendoerfer, R., Castelijns, R., Crede, V., Ehmanns, A., Ernst, J., Fabry, I., Flemming, H., Foesel, A., Fuchs, M., Funke, Ch, Gothe, R., Gridnev, A., Gutz, E., Hoeffgen, St, Horn, I., Hossl, J., Kalinowsky, H., Klein, F., Klempt, E., Koch, H., Konrad, M., Kopf, B., Krusche, B., Langheinrich, J., Löhner, H., Lopatin, I., Lotz, J., Mattaey, H., Menze, D., Messchendorp, J., Nikonov, V. A., Novinski, D., Ostrick, M., van Pee, H., Radkov, A., Sarantsev, A. V., Schadmand, S., Schmidt, C., Schmieden, H., Schoch, B., Suft, G., Sumachev, V., Szczepanek, T., Thoma, U., Walther, D., Weinheimer, Ch, and KVI - Center for Advanced Radiation Technology

Subjects
Physics, Nuclear and High Energy Physics, Range (particle radiation), Proton, Nuclear Theory, Particle accelerator, Photon energy, Omega, ETA, MESONS, DECAYS, law.invention, LAMBDA, Nuclear physics, RELATIVISTIC QUARK-MODEL, law, PHOTON ENERGIES, STRANGE-BARYON SPECTRUM, Physics::Accelerator Physics, High Energy Physics::Experiment, SIGMA(0), FORCES, Nuclear Experiment, RESONANCES
Abstract

Differential and total cross-sections for photoproduction of gamma proton to proton pi0 omega and gamma proton to Delta+ omega were determined from measurements of the CB-ELSA experiment, performed at the electron accelerator ELSA in Bonn. The measurements covered the photon energy range from the production threshold up to 3GeV.

Published
2007

9. Measurement of the beam asymmetry in eta-photoproduction off the proton

Author

Elsner, D., Anisovich, A. V., Anton, G., Bacelar, J. C. S., Bantes, B., Bartholomy, O., Bayadilov, D. E., Beck, R., Beloglazov, Y. A., Bogendoerfer, R., Castelijns, R., Crede, V., Dutz, H., Ehmanns, A., Essig, K., Ewald, R., Fabry, I., Flemming, H., Fornet-Ponse, K., Fuchs, M., Funke, C., Gothe, R., Gregor, R., Gridnev, A. B., Gutz, E., Hoeffgen, S., Hoffmeister, P., Horn, I., Hoessl, J., Jaegle, I., Junkersfeld, J., Kammer, H. Kalinowsky S., Klein, V. Kleber Frank, Klein, Friedrich, Klempt, E., Koch, H., Konrad, M., Kopf, B., Kotulla, M., Krusche, B., Lang, M., Langheinrich, J., Löhner, H., Lopatin, I. V., Lotz, J., Ay, S. Lugert H. Matth, Menze, D., Mertens, T., Messchendorp, J. G., Metag, V., Morales, C., Nanova, M., Nikonov, V. A., Novinski, D. V., Novotny, R., Ostrick, M., Pant, L. M., Van Pee, H., Pfeiffer, M., Radkov, A. K., Sarantsev, A. V., Schadmand, S., Schmidt, C., Schmieden, H., Schoch, B., Shende, S., Ule, A. S., Sumachev, V. V., Szczepanek, T., Thoma, U., Trnka, D., Walther, D., Weinheimer, C., Wendel, C., Suft, G., Suele, A., and KVI - Center for Advanced Radiation Technology

Subjects
Nuclear and High Energy Physics, Photon, POLARIZATION, Proton, media_common.quotation_subject, Partial wave analysis, FOS: Physical sciences, ELSA, Asymmetry, THRESHOLD, Nuclear physics, Nuclear Experiment (nucl-ex), Nuclear Experiment, media_common, Physics, Range (particle radiation), COHERENT BREMSSTRAHLUNG, Bremsstrahlung, ELECTROPRODUCTION, Cover (topology), RELATIVISTIC QUARK-MODEL, STRANGE-BARYON SPECTRUM, MESON PHOTOPRODUCTION, FORCES, Beam (structure)
Abstract

The beam asymmetry, $\Sigma$, was measured at ELSA in the reaction $\vec \gamma p \to \eta p$ using linearly polarised tagged photon beams, produced by coherent bremsstrahlung off a diamond. The crystal was oriented to provide polarised photons in the energy range $E_\gamma = 800$ to 1400 MeV with the maximum polarisation of $P_\gamma = 49$ % obtained at 1305 MeV. Both dominant decay modes of the $\eta$ into two photons and $3\pi^0$ were used to extract the beam asymmetry from the azimuthal modulation of the cross section. The measurements cover the angular range $\Theta_\text{cm}\simeq 50$ -- 150 degrees. Large asymmetries up to 80 % are observed, in agreement with a previous measurement. The eta-MAID model and the Bonn--Gatchina partial wave analysis describe the measurements, but the required partial waves differ significantly., Comment: 8 pages, 8 figures, submitted to EPJA

Published
2007
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10. Photoproduction of π0-mesons off protons from the ∆(1232) region to Eγ = 3 GeV: Photoproduction of π0-mesons off protons from the ∆(1232) region to Eγ = 3 GeV

Author

van Pee, H., Bartholomy, O., Crede, V., Anisovich, A. V., Anton, G., Bantes, R., Beloglazov, Yu., Bogendoerfer, R., Castelijns, Ralph, Ehmanns, A., Ernst, J., Fabry, I., Flemming, H., Foesel, A., Fuchs, M., Funke, Ch., Gothe, R., Gridnev, A., Gutz, E., Hoeffgen, St., Horn, I., Hoessl, J., Junkersfeld, J., Kalinowsky, H., Klein, F., Klempt, E., Koch, H., Konrad, M., Kopf, B., Krusche, B., Langheinrich, J., Loehner, H., Lopatin, I., Lotz, J., Matthaey, H., Menze, D., Messchendorp, J., Nikonov, V. A., Novinski, D., Ostrick, M., Radkov, A., Sarantsev, A. V., Schadmand, Susan, Schmidt, C., Schmieden, H., Schoch, B., Suft, G., Sumachev, V., Szczepanek, T., Thoma, U., KVI - Center for Advanced Radiation Technology, and Research unit Nuclear & Hadron Physics

Subjects
RELATIVISTIC QUARK-MODEL, MAGNETIC MOMENTS, NEUTRAL PION-PHOTOPRODUCTION, PHOTON ENERGIES, STRANGE-BARYON SPECTRUM, High Energy Physics::Experiment, SUM RULE, NEAR-THRESHOLD, FORCES, Nuclear Experiment, CROSS-SECTION, ETA
Abstract

Photoproduction of pi(0)-mesons was studied with the Crystal-Barrel detector at ELSA for incident energies from 300 MeV to 3 GeV. Differential cross-sections d sigma/d Omega, d sigma/dt, and the total cross-section are presented. For E (gamma)

Published
2007

11. Neutral-pion photoproduction off protons in the energy range 0.3 GeV kleiner E(gamma) kleiner 3 GeV

Author

Bartholomy, O., Crede, V., Flemming, J. K., Fosel, P. S., Freiesleben, H., Fuchs, M., Funke, C., Gothe, R., Gridnev, A. B., Gutz, E., Hoeffgen, S., Horn, I., Anisovich, A., Hossl, J., Joosten, R., Junkersfeld, J., Kalinowsky, H., Klein, F., Klempt, E., Koch, H., Konrad, M., Kopf, B., Krusche, B., Anton, G., Langheinrich, J., Loehner, H., Lopatin, I. V., Lotz, J., Matthay, G. G., Menze, D., Messchendorp, J. G., Morales, C., Novinski, D., Ostrick, M., Bantes, R., van Pee, H., Radkov, J. O., Reinnarth, J., Sarantsev, A., Schadmand, S., Schmidt, C., Schmieden, H., Schoch, B., Suft, G., Sumachev, V. V., Beloglazov, Y. A., Szczepanek, T., Thoma, U., Walther, D., Weinheimer, Ch., Bogendoerfer, R., Ehmanns, A., Ernst, J., and Fabry, I.

Subjects
experimental results [four-pi-detector], exclusive reaction [photon p], tagged beam [photon], angular dependence [differential cross section], ddc:550, Bonn ELSA Stor, partial wave analysis, intermediate state [nucleon resonance], energy dependence [channel cross section], photoproduction [pi0], +p+pi0%22">photon p --> p pi0, 0.3-3.0 GeV
Abstract

Single pi(0) photoproduction has been studied with the CB-ELSA experiment at Bonn using tagged photon energies between 0.3 and 3.0 GeV. The experimental setup covers a very large solid angle of similar to98% of 4pi. Differential cross sections dsigma/dOmega have been measured. Complicated structures in the angular distributions indicate a variety of different resonances being produced in the s channel intermediate state gammap-->N-*(Delta(*))-->ppi(0). A combined analysis including the data presented in this letter along with other data sets reveals contributions from known resonances and evidence for a new resonance N(2070)D-15.

Published
2005

12. Photoproduction of eta mesons off protons for 0.75 GeV kleiner E(gamma) kleiner 3 GeV

Author

Crede, V., Bartholomy, O., Flemming, J. K., Fosel, P. S., Freiesleben, H., Fuchs, M., Funke, C., Gothe, R., Gridnev, A. B., Gutz, E., Hoeffgen, S., Horn, I., Anisovich, A., Hossl, J., Joosten, R., Junkersfeld, J., Kalinowsky, H., Klein, F., Klempt, E., Koch, H., Konrad, M., Kopf, B., Krusche, B., Anton, G., Langheinrich, J., Loehner, H., Lopatin, I. V., Lotz, J., Matthay, G. G., Menze, D., Messchendorp, J. G., Morales, C., Novinski, D., Ostrick, M., Bantes, R., van Pee, H., Radkov, J. O., Reinnarth, J., Sarantsev, A., Schadmand, S., Schmidt, C., Schmieden, H., Schoch, B., Suft, G., Sumachev, V. V., Beloglazov, Y. A., Szczepanek, T., Thoma, U., Walther, D., Weinheimer, Ch., Bogendoerfer, R., Ehmanns, A., Ernst, J., and Fabry, I.

Subjects
photoproduction [eta], +p+eta%22">photon p --> p eta, Astrophysics::High Energy Astrophysical Phenomena, width [nucleon resonance], +2photon%22">eta --> 2photon, decay modes [eta], mass spectrum [nucleon resonance], energy dependence [channel cross section], experimental results [four-pi-detector], exclusive reaction [photon p], 0.7-3.0 GeV, ddc:550, Bonn ELSA Stor, High Energy Physics::Experiment, angular distribution, intermediate state [nucleon resonance], Nuclear Experiment, +3pi0%22">eta --> 3pi0, isobar model
Abstract

Total and differential cross sections for the reaction p(gamma,eta)p have been measured for photon energies in the range from 750 MeV to 3 GeV. The low-energy data are dominated by the S-11 wave which has two poles in the energy region below 2 GeV. Eleven nucleon resonances are observed in their decay into peta. At medium energies we find evidence for a new resonance N(2070)D-15 with (M,Gamma)=(2068+/-22, 295+/-40) MeV. At gamma energies above 1.5 GeV, a strong peak in the forward direction develops, signaling the exchange of vector mesons in the t channel.

Published
2005

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