Dresden 2013 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 42: Hadronenstruktur und -spektroskopie
HK 42.5: Vortrag
Dienstag, 5. März 2013, 18:00–18:15, HSZ-304
Symmetric Møller/Bhabha luminosity monitor for the OLYMPUS experiment — •Roberto Perez Benito — Johannes Gutenberg Universität Mainz
Recent determinations of the proton electric to magnetic form factor ratio
indicate an unexpected discrepancy between the ratio obtained using
polarisation transfer measurements and the ratio from the Rosenbluth
separation technique in unpolarised cross section measurements.
This discrepancy has been explained theoretically as the effect of two-photon
exchange.
The OLYMPUS experiment at DESY proposed to measure the ratio of
positron-proton and electron-proton elastic scattering cross sections.
The experiment utilised beams of electrons and positrons in the DORIS ring
at 2.0 GeV incident on an unpolarized internal hydrogen gas target and
the BLAST detector from the MIT-Bates Linear Accelerator Center with modest
upgrades.
In order to reduce the systematic error from the determination of
luminosity, redundant measurements of the relative luminosity were necessary.
The symmetric Møller/Bhabha luminosity monitor built at the University
of Mainz consisted of two symmetric arrays of lead fluoride (PbF2)
crystals. Results on the performance of the symmetric Møller/Bhabha
luminosity monitor will be presented in this contribution.