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Photoproduction of neutral pion pairs from the proton |
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| Authors: | M Wolf J Ahrens R Beck V Hejny JD Kellie M Kotulla B Krusche V Kuhr R Leukel V Metag JC Nacher R Novotny V Olmos de León RO Owens F Rambo A Schmidt M Schumacher U Siodlaczek H Ströher J Weiß F Wissmann |
| Institution: | II. Physikalisches Institut, Universit?t Gie?en, D-35392 Gie?en, Germany, DE Institut für Kernphysik, Johannes-Gutenberg-Universit?t Mainz, D-55099 Mainz, Germany, DE Department of Physics and Astronomy, University of Glasgow, Glasgow G128QQ, UK, GB II. Physikalisches Institut, Universit?t G?ttingen, D-37073 G?ttingen, Germany, DE Departamento de F?sica Teórica and IFIC, Universidad de Valencia, 46100 Burjassot, Spain, ES Physikalisches Institut, Universit?t Tübingen, D-72076 Tübingen, Germany, DE |
| Abstract: | Double neutral pion photoproduction from the proton has been measured at MAMI for photon energies between threshold and 820 MeV. The reaction was identified by an invariant mass and missing mass analysis. From threshold up to 370 MeV the total cross-section does not exceed 30 nb. For higher energies it shows a smooth rise until it reaches a maximum of about 10 μb at E γ = 740 MeV. Dalitz plots of m 2(π0π0) versus m 2(p,π0) for seven bins of incident photon energy have been analysed. For E γ > 610 MeV, a strong contribution of a sequential decay is observed with the Δ(1232)-resonance as intermediate state. A comparison to model calculations shows that these sequential decays presumably originate from the D 13(1520) and also the P 11(1440)-resonance. Received: 6 June 2000 / Accepted: 18 August 2000 |
| Keywords: | PACS 13 60 Le Meson production – 25 20 Lj Photoproduction reactions |
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