Bochum 2009 – scientific programme
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HK: Fachverband Hadronen und Kerne
HK 70: Hadron Structure and Spectroscopy II
HK 70.7: Talk
Thursday, March 19, 2009, 18:30–18:45, H-ZO 30
First Results of exclusive ρ0 Production from the Recoil Detector at HERMES — •Roberto Perez-Benito — II. Phys. Institut, Univ. Giessen, Giessen, Germany
The HERMES experiment (HERa MEasurement of Spin) at DESY was designed to study the spin structure of the nucleon by semi-inclusive deep inelastic scattering. Here, we report on hard exclusive processes that can be understood in terms of Generalised Patron Distributions (GPDs). The accumulated HERMES data offer access to GPDs in different combinations of beam charge and beam helicity asymmetries. The ratio of the cross-sections of ρ0 meson production between hydrogen and deuterium will provide an insight into the relative contribution to the nucleon cross-section from quarks and gluons.
In January 2006 a Recoil Detector was installed that surrounded the internal gas target of the HERMES experiment. The HERMES Recoil Detector consisted of three components: a silicon strip detector inside the vacuum, a scintillating fiber tracker and the photon detector with three layers of tungsten and scintillator bars in three different orientations. All three detectors were located inside a solenoidal magnet which provided a 1T longitudinal magnetic field. The detector improves the selection of exclusive events by a direct measurement of the recoiling target nucleon in an intermediate momentum range from 0.1 to 1.4 GeV/c as well as by rejecting non-exclusive background.