Measurement of the beam asymmetry<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>Σ</mml:mi></mml:mrow></mml:math>in the forward direction for<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>γ⃗</mml:mi><mml:mi>p</mml:mi><mml:mo>→</mml:mo><mml:mi>p</mml:mi><mml:msup><mml:mi>π</mml:mi><mml:mrow><mml:mn>0</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>

Sparks, N. A.; Credé, V.; Anisovich, A. V.; Bacelar, J. C. S.; Bantes, R.; Bartholomy, O.; Bayadilov, D.; Beck, R.; Beloglazov, Y. A.; Castelijns, R.; Elsner, D.; Ewald, R.; Frommberger, F.; Funke, Chr.; Gregor, R.; Gridnev, A.; Gutz, E.; Hillert, W.; Hoffmeister, P.; Jaeglé, I.; Junkersfeld, J.; Kalinowsky, H.; Kammer, S.; Klein, Frank; Клейн, Ф.; Klempt, E.; Kotulla, M.; Krusche, B.; Löhner, H.; Lopatin, I.; Lugert, S.; Menze, D.; Mertens, T.; Messchendorp, J. G.; Metag, V.; Nanova, M.; Nikonov, V. A.; Novinski, D.; Novotny, R.; Ostrick, M.; Pant, L. M.; Pee, H. van; Pfeiffer, M.; Roy, A.; Sarantsev, A.; Schadmand, S.; Schmidt, Ch.; Schmieden, H.; Schoch, B.; Shende, S.; Sokhoyan, V.; Süle, A.; Sumachev, V. V.; Szczepanek, T.; Thoma, U.; Trnka, D.; Varma, R.; Walther, Dirk; Wendel, Ch.; Wilson, A.

doi:10.1103/physrevc.81.065210

Cited by 32 publications

(9 citation statements)

References 65 publications

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“…Cross-section [14,15], [16,17], and double-polarized C x [18] data for γp → π 0 p have had a lesser impact. For this reason, in the next section we focus mainly on the neutron target fits and multipoles.…”

Section: Databasementioning

confidence: 99%

Updated SAID analysis of pion photoproduction data

et al. 2012

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Energy-dependent and single-energy fits to the existing pion photoproduction database have been updated to cover the region from threshold to 2.7 GeV in the laboratory photon energy. Revised resonance photo-decay couplings have been extracted and compared to previous determinations. The influence of recent measurements is displayed. Remaining problems and future approaches are discussed.Comment: 9 pages, 6 figures, 3 table

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Section: Databasementioning

confidence: 99%

Updated SAID analysis of pion photoproduction data

et al. 2012

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“…Previous measurements for π 0 production have concentrated on reactions off the free proton. Precise angular distributions and polarization observables were reported in [23][24][25][26][27][28][29][30][31][32]. Until now, data for π 0 production involving neutrons were only available for inclusive measurements off the deuteron [33], the beam asymmetry for γn → nπ 0 [34] and the cross section data from [10].…”

Section: Introductionmentioning

confidence: 99%

First measurement of the polarization observable E and helicity-dependent cross sections in single π0 photoproduction from quasi-free nucleons

et al. 2017

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The double-polarization observable E and the helicity-dependent cross sections σ 1/2 and σ 3/2 have been measured for the first time for single π 0 photoproduction from protons and neutrons bound in the deuteron at the electron accelerator facility MAMI in Mainz, Germany. The experiment used a circularly polarized photon beam and a longitudinally polarized deuterated butanol target. The reaction products, recoil nucleons and decay photons from the π 0 meson were detected with the Crystal Ball and TAPS electromagnetic calorimeters. Effects from nuclear Fermi motion were removed by a kinematic reconstruction of the π 0 N final state. A comparison to data measured with a free proton target showed that the absolute scale of the cross sections is significantly modified by nuclear final-state interaction (FSI) effects. However, there is no significant effect on the asymmetry E since the σ 1/2 and σ 3/2 components appear to be influenced in a similar way. Thus, the best approximation of the two helicity-dependent cross sections for the free neutron is obtained by combining the asymmetry E measured with quasi-free neutrons and the unpolarized cross section corrected for FSI effects under the assumption that the FSI effects are similar for neutrons and protons.

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“…Previous experimental efforts for π 0 production have concentrated on the measurement of angular distributions and polarization observables for the free proton target [13][14][15][16][17][18][19][20][21][22]. The recent measurements of the double polarization observables G (linearly polarized beam, longitudinally polarized target [20]), E (circularly polarized beam, longitudinally polarized target [21]), and C ⋆ x (circularly polarized beam, polarization of recoil nucleon [22]) for this reaction had significant impact on the analysis of nucleon resonance properties.…”

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confidence: 99%

Photoproduction ofπ0Mesons off Neutrons in the Nucleon Resonance Region

Dieterle¹,

Keshelashvili²,

Ahrens³

et al. 2014

Phys. Rev. Lett.

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Precise angular distributions have been measured for the first time for the photoproduction of π0 mesons off neutrons bound in the deuteron. The effects from nuclear Fermi motion have been eliminated by a complete kinematic reconstruction of the final state. The influence of final-state-interaction effects has been estimated by a comparison of the reaction cross section for quasifree protons bound in the deuteron to the results for free protons and then applied as a correction to the quasifree neutron data. The experiment was performed at the tagged photon facility of the Mainz Microtron MAMI with the Crystal Ball and TAPS detector setup for incident photon energies between 0.45 and 1.4 GeV. The results are compared to the predictions from reaction models and partial-wave analyses based on data from other isospin channels. The model predictions show large discrepancies among each other and the present data will provide much tighter constraints. This is demonstrated by the results of a new analysis in the framework of the Bonn-Gatchina coupled-channel analysis which included the present data.

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Measurement of the beam asymmetryΣin the forward direction forγ⃗p→pπ0

Cited by 32 publications

References 65 publications

Updated SAID analysis of pion photoproduction data

Updated SAID analysis of pion photoproduction data

First measurement of the polarization observable E and helicity-dependent cross sections in single π0 photoproduction from quasi-free nucleons

Photoproduction ofπ0Mesons off Neutrons in the Nucleon Resonance Region

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