Electron- and positron-proton elastic scattering in CLAS
There is a significant disagreement between measurements of the proton electric form factor, G{sup p}{sub E}, using Rosenbluth separations and polarization transfer. This disagreement, if not explained, could pose a fundamental challenge to our understanding of electron scattering or proton structure. Two-photon exchange (TPE) processes, although not fully calculable, are the most likely explanation of this disagreement. We will definitively test this assertion by comparing the electron-proton and positron-proton elastic scattering cross section in the Jefferson Lab CLAS. We will make a mixed identical electron and positron tertiary beam by passing a 5.5 GeV primary electron beam through a radiator to make a photon beam and then passing the photon beam through a converter to make electron-positron pairs. Measuring the elastic cross sections simultaneously using identical lepton beams should significantly reduce systematic uncertainties.
- Research Organization:
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- AC05-06OR23177
- OSTI ID:
- 1059420
- Report Number(s):
- JLAB-PHY-09-1092; DOE/OR/23177-2439
- Journal Information:
- AIP Conf.Proc., Vol. 1160; Conference: International Workshop on Positrons at Jefferson Lab (JPOS 09), 25-27 Mar 2009. Newport News, Virginia
- Country of Publication:
- United States
- Language:
- English
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