Dresden 2000 – scientific programme
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HK: Physik der Hadronen und Kerne
HK 21: Elektromagnetische und hadronische Proben III
HK 21.2: Talk
Thursday, March 23, 2000, 14:45–15:00, B 154
Dilepton Production in Photonuclear Reactions — •S. Schadmand — II. Physikalisches Institut, Universität Gießen
Preliminary results of the observation of dileptons produced in
photonuclear reactions are presented.
The goal is to investigate virtual Compton scattering
below the ρ-meson production threshold.
This should enable the extraction of electromagnetic form factors
in the time-like region.
Several targets (LH2, C, CA, and Pb) were employed in combination
with a photon beam with a maximum energy of 880 MeV.
Dileptons were detected with the electromagnetic spectrometer TAPS
in parallel to the ongoing meson production experiments
at the tagged-photon facility at MAMI-B (Mainz).
In γ+p reactions the elementary processes can be observed while
in-medium effects might be observed with the heavier targets.
The experiments are of exploratory nature.
In particular, the contribution of the Bethe-Heitler process is a concern.
As a first step in this study,
πo- and η-Dalitz decays have been measured.
Eventually, the results should complement measurements of dilepton
production in heavy ion reactions, aiming at an understanding of the
in-medium behavior of vector mesons.