The OLYMPUS Experiment at DESY

Köhl, M.; Elouadrhiri, L.; Grames, Jospeh; Melnitchouk, Wally; Voutier, E.; Forest, Tony A.

doi:10.1063/1.3232027

Cited by 10 publications

(13 citation statements)

References 6 publications

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“…Including the best hadronic calculations available yields consistency between the two techniques, and good separation of G E and G M up to high Q 2 [13,15]. Comparisons of electron-proton and positron-proton scattering can be used to isolate TPE contributions [51], and a series of such measurements are currently planned or underway [52][53][54].…”

Section: Previous Measurementsmentioning

confidence: 99%

Low-Q2measurements of the proton form factor ratioμpGE/GM

Ron¹,

Zhan²,

Glister³

et al. 2011

Phys. Rev. C

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We present an updated extraction of the proton electromagnetic form factor ratio, µpGE/GM , at low Q 2 . The form factors are sensitive to the spatial distribution of the proton, and precise measurements can be used to constrain models of the proton. An improved selection of the elastic events and reduced background contributions yielded a small systematic reduction in the ratio µpGE/GM compared to the original analysis.

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Section: Previous Measurementsmentioning

confidence: 99%

Low-Q2measurements of the proton form factor ratioμpGE/GM

Ron¹,

Zhan²,

Glister³

et al. 2011

Phys. Rev. C

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“…Cross sections in the kinematical range of 0.5 < Q 2 < 2.0 (GeV/c) 2 and 0.2 < ε < 0.9 can be measured. The third is the OLYMPUS experiment [50], where the DORIS lepton storage ring at DESY will be used to extract the ratio R e + e − from Q 2 = 0.6 (GeV/c) 2 and ε = 0.90, to Q 2 = 2.2 (GeV/c) 2 and ε = 0.35.…”

Section: A Form Factors and The Tpe Amplitudesmentioning

confidence: 99%

Reexamination of phenomenological two-photon exchange corrections to the proton form factors ande±pscattering

2011

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We extract the two-photon exchange (TPE) contributions to electron-proton elastic scattering using two parametrizations and compare the results to different phenomenological extractions and direct calculations of the TPE effects. We find that many of the extractions give similar results, and highlight the common assumptions and the impact of not including these assumptions. We provide a simple parametrization of the TPE contribution to the unpolarized cross section, along with an estimate of the fit uncertainties and the uncertainties associated with the model dependence of the extractions. We look at the contributions as extracted from various e-p elastic scattering observables, and make predictions for ratio of positron-proton to electron-proton elastic scattering cross sections.

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“…The accumulation of data in three experiments aimed at measuring R to a high degree of precision has been completed to date. This are the experiment described here and performed at the VEPP-3 storage ring (Budker Institute of Nuclear Physics, Novosibirsk, Russia), the OLYMPUS experiment [47] at the DORIS storage ring (DESY, Hamburg, Germany), and the experiment with the PROTON FORM FACTORS AND TWO-PHOTON EXCHANGE 397 CLAS detector [48] at the TJNAF (Newport News, USA). The Q 2 and ε kinematical regions covered in these experiments are shown in Fig.…”

Section: Two-photon Exchangementioning

confidence: 99%

Proton form factors and two-photon exchange in elastic electron-proton scattering

et al. 2015

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Proton electromagnetic form factors are among the most important sources of information about the internal structure of the proton. Two different methods for measuring these form factors, the method proposed by Rosenbluth and the polarization-transfer method, yield contradictory results. It is assumed that this contradiction can be removed upon taking into account the hard part of the contribution of two-photon exchange to the cross section for elastic electron-proton scattering. This contribution can measured experimentally via a precision comparison of the cross sections for the elastic scattering of positrons and electrons on protons. Such a measurement, performed at the VEPP-3 storage ring in Novosibirsk at the beam energies of 1.6 and 1.0 GeV for positron (electron) scattering angles in the ranges of θ e = 15 • −25 • and 55 • −75 • in the first case and in the range of θ e = 65 • −105 • in the second case is described in the present article. Preliminary results of this experiment and their comparison with theoretical predictions are described.

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The OLYMPUS Experiment at DESY

Cited by 10 publications

References 6 publications

Low-Q2measurements of the proton form factor ratioμpGE/GM

Low-Q2measurements of the proton form factor ratioμpGE/GM

Reexamination of phenomenological two-photon exchange corrections to the proton form factors ande±pscattering

Proton form factors and two-photon exchange in elastic electron-proton scattering

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