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Threshold enhancement in η photoproduction from 2H and 4He |
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| Authors: | V Hejny J Weiß P Achenbach J Ahrens JRM Annand R Beck M Kotulla B Krusche V Kuhr R Leukel IJD MacGregor V Metag R Novotny V Olmos de León F Rambo A Schmidt M Schumacher U Siodlaczek H Ströher F Wissmann M Wolf |
| Institution: | Institut für Kernphysik, Forschungszentrum Jülich, D-52425, Jülich, Germany, DE II. Physikalisches Institut, Universit?t Gie?en, D-35392 Gie?en, Germany, DE Institut für Kernphysik, Universit?t Mainz, D-55099 Mainz, Germany, DE Department of Physics and Astronomy, University of Glasgow, Glasgow G128QQ, UK, GB Department of Physics and Astronomy, University of Basel, Ch-4056 Basel, Switzerland, CH II. Physikalisches Institut, Universit?t G?ttingen, D-37073 G?ttingen, Germany, DE Physikalisches Institut, Universit?t Tübingen, D-72076 Tübingen, Germany, DE |
| Abstract: | The photoproduction of η-mesons from 2H and 4He has been studied for energies close to the production thresholds. The experiments were carried out with the tagged photon beam of the Mainz MAMI accelerator. The η-mesons were detected via their two photon decays with the electromagnetic calorimeter TAPS. Total cross-sections, angular and momentum distributions of the η-mesons have been determined for both reactions. The total cross-sections in the threshold region show a large enhancement over the predictions of a participant-spectator model, indicating significant final-state interaction effects. The results are compared to recent model calculations taking into account nucleon-nucleon and nucleon-η final-state interaction effects on different levels of sophistication. Received: 23 November 2001 / Accepted: 11 February 2002 |
| Keywords: | PACS 13 60 Le Meson production – 14 40 Aq π K and η mesons – 25 20 Lj Photoproduction reactions |
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