Eur. Phys. J. A (2010) 43: 269-282
https://doi.org/10.1140/epja/i2010-10925-y

Regular Article - Experimental Physics

Radiative π⁰ photoproduction on protons in the Δ⁺ (1232) region

¹ Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, Mainz, Germany
² Helmholtz-Institut für Strahlen- und Kernphysik, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
³ Institut für Physik, Universität Basel, Basel, Switzerland
⁴ Department of Physics and Astronomy, University of Glasgow, Glasgow, UK
⁵ Petersburg Nuclear Physics Institute, Gatchina, Russia
⁶ INFN Sezione di Pavia, Pavia, Italy
⁷ School of Physics, University of Edinburgh, Edinburgh, UK
⁸ Center for Nuclear Studies, The George Washington University, Washington, D.C., USA
⁹ University of California at Los Angeles, Los Angeles, CA, USA
¹⁰ Lebedev Physical Institute, Moscow, Russia
¹¹ II. Physikalisches Institut, Justus Liebig-Universität Gießen, Gießen, Germany
¹² Mount Allison University, Sackville, NB, Canada
¹³ Institute for Nuclear Research, Moscow, Russia
¹⁴ Rudjer Boskovic Institute, Zagreb, Croatia
¹⁵ Kent State University, Kent, OH, USA
¹⁶ The Catholic University of America, Washington, D.C., USA

^* e-mail: schumans@kph.uni-mainz.de

Received: 7 December 2009
Revised: 15 January 2010
Published online: 17 February 2010

Abstract

The reaction γp → pπ ⁰γ′ has been measured with the Crystal Ball/TAPS detectors using the energy-tagged photon beam at the electron accelerator facility MAMI-B. Energy and angular differential cross-sections for the emitted photon γ′ and angular differential cross-sections for the π⁰ have been determined with high statistics in the energy range of the Δ⁺ (1232)-resonance. Cross-sections and the ratio of the cross-section to the nonradiative process γp → pπ ⁰ are compared to theoretical reaction models, having the anomalous magnetic moment κ _Δ as free parameter. As the shape of the experimental distributions is not reproduced in detail by the model calculations, currently no extraction of κ _Δ is feasible.