Eur. Phys. J. A (2005) 26: 135-140
https://doi.org/10.1140/epja/i2005-10158-3

Original Article

Measurement of the G asymmetry for the γp↦Nπ channels in the Δ(1232) resonance region

¹ Institut für Experimentalphysik, Ruhr-Universität Bochum, D-44801, Bochum, Germany
² Physikalisches Institut, Universität Bonn, D-53115, Bonn, Germany
³ Subatomaire en Stralingsfysica, Universiteit Gent, B-9000, Gent, Belgium
⁴ CEA Saclay, DSM/DAPNIA/SPhN, F-91191, Gif-sur-Yvette Cedex, France
⁵ Department of Physics and Astronomy, University of Glasgow, G12 8QQ, Glasgow, UK
⁶ II. Physikalisches Institut, Universität Göttingen, D-37073, Göttingen, Germany
⁷ Institut für Kernphysik, Universität Mainz, D-55099, Mainz, Germany
⁸ INR, Academy of Science, Moscow, Russia
⁹ Department of Physics, Nagoya University, Nagoya, Japan
¹⁰ CIRSE, Nagoya University, Nagoya, Japan
¹¹ INFN, Sezione di Pavia, I-27100, Pavia, Italy
¹² Dipartimento di Fisica Nucleare e Teorica, Università di Pavia, I-27100, Pavia, Italy
¹³ Physikalisches Institut, Universität Tübingen, D-72076, Tübingen, Germany

^* e-mail: pedroni@pv.infn.it

Received: 22 March 2005
Accepted: 19 September 2005
Published online: 31 October 2005

Abstract

The G asymmetry of the γp↦Nπ reaction has been measured for the first time for E _γ = 340±14 MeV. This observable, for which very scarce published data exist, plays an important role to disentangle the contributions of the various nucleon resonances. The experiment, performed at the Mainz microtron MAMI, used a 4π-detector system, a linearly polarized, tagged photon beam, and a longitudinally polarized proton target.