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EPJ A - Hadrons and Nuclei
Hadrons and Nuclei


Eur. Phys. J. A 10, 365-371

Coherent and incoherent ${\pi^0}$ photoproduction from the deuteron

U. Siodlaczek1, P. Achenbach2, J. Ahrens3, J.R.M. Annand4, H.-J. Arends3, R. Beck3, R. Bilger1, H. Clement1, V. Hejny5, M. Kotulla2, B. Krusche6, V. Kuhr7, R. Leukel3, J.C. McGeorge4, V. Metag2, R. Novotny2, V. Olmos de León3, F. Rambo7, M. Schepkin8, A. Schmidt3, I. Seluzhenkov8, 9, H. Ströher5, G.J. Wagner1, Th. Walcher3, J. Weiß2, F. Wissmann7 and M. Wolf2

1  Physikalisches Institut, Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany
2  II. Physikalisches Institut, Universität Gieß en, D-35392 Gießen, Germany
3  Institut für Kernphysik, Universität Mainz, D-55099 Mainz, Germany
4  Department of Physics and Astronomy, University of Glasgow, Glasgow G128 QQ, UK
5  Institut für Kernphysik, Forschungszentrum Jülich, D-52425 Jülich, Germany
6  Institut für Physik und Astronomie, Universität Basel, Klingelbergstr. 82, CH-4056 Basel, Switzerland
7  II. Physikalisches Institut, Universität Göttingen, D-37073 Göttingen, Germany
8  Institute for Theoretical and Experimental Physics, Moscow 117218, Russia
9  Moscow State Engineering Physics Institute, Moscow 115409, Russia

(Received: 13 February 2001 / Revised version: 11 April 2001 Communicated by M. Garçon)

Abstract
Differential cross-sections for the reactions $d(\gamma,\pi^0)d$ and $d(\gamma,\pi^0)pn$ have been measured at MAMI with the TAPS detector setup in the energy range 140 MeV $< E_\gamma < 306$ MeV. By use of the Glasgow tagging spectrometer an 0.8 MeV energy resolution for photons incident on the target was achieved. The ${\pi^0}$ missing energy resolution was sufficient for a reliable separation of coherent and incoherent channels. The data for the break-up channel exhibit very strong final state interaction effects, whereas the observed angular dependence of the inclusive process $d(\gamma,\pi^0)X$ is in quantitative agreement with predictions for a quasi-free process. The observed absolute $d(\gamma,\pi^0)X$ cross-sections, on the other hand, are significantly smaller than predicted by the quasi-free process for $E_\gamma \gtrsim 250$ MeV. Associating this failure with the ${\pi^0}$ photoproduction on the neutron would suggest that its cross-section is up to 25% below the presently believed value.

PACS
13.60.Le - Meson production.
25.20.Lj - Photoproduction reactions.

© Società Italiana di Fisica, Springer-Verlag 2001

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