Dresden 2013 – scientific programme

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HK: Fachverband Physik der Hadronen und Kerne

HK 42: Hadronenstruktur und -spektroskopie

HK 42.6: Talk

Tuesday, March 5, 2013, 18:15–18:30, HSZ-304

OLYMPUS Luminosity Monitoring — •Ozgur Ates — Hampton University, Hampton, Virginia, USA

The OLYMPUS experiment at DESY has been measuring the ratio of positron-proton and electron-proton elastic scattering cross sections to quantify the effect of two-photon exchange, which is widely considered to be responsible for the discrepancy between measurements of the proton electric to magnetic form factor ratio with the Rosenbluth and polarization transfer methods. In order to control the systematic uncertainties to the percent level, the luminosities are monitored redundantly with high precision by measuring the rates for symmetric Moller and Bhabha scattering, and by measuring the ep-elastic count rates at forward angles and low momentum transfer with tracking telescopes based on GEM (Gas Electron Multiplier) and MWPC (Multi Wire Proportional Chamber) technology. During two data taking periods, performances of GEM and MWPC luminosity monitors will be presented.