Speaker
Dr
Uwe Schneekloth
(DESY)
Description
The OLYMPUS experiment will measure the two-photon exchange amplitude in the elastic
electron-proton scattering. This amplitude is a possible explanation for the significant,
experimental discrepancy in the determination of the ratio of the proton electric to magnetic form
factors, $R=\mu_p G_E^p/G_M^p$, determined using Rosenbluth separation and polarization
transfer techniques. A measurement of the elastic scattering cross section ratio,
$\sigma_{e^+p}/\sigma_{e^-p}$, will provide a direct measurement of the two-photon
exchange amplitude. The OLYMPUS experiment was carried out at the DESY laboratory
in Hamburg, Germany using the 2.01 GeV electron and positron beams
of the DORIS storage ring incident on an internal hydrogen gas target.
Independent luminosity monitors were operated in parallel to the main
spectrometer during data taking to allow for a precise relative luminosity
measurement. Approximately 4.45 fb$^{-1}$ of data were collected. The
OLYMPUS experiment and the status of the analysis will be discussed.
Primary author
Dr
Uwe Schneekloth
(DESY)
