DOI: 10.1140/epja/i2002-10153-2
First measurement of the helicity-dependent
differential cross-section
J. Ahrens1, S. Altieri2, 3, J.R.M. Annand4, G. Anton5, H.-J. Arends1, K. Aulenbacher1, R. Beck1, C. Bradtke6, A. Braghieri2, N. d'Hose7, D. Drechsel1, H. Dutz8, S. Goertz6, P. Grabmayr9, K. Hansen10, J. Harmsen6, D. von Harrach1, S. Hasegawa11, T. Hasegawa12, E. Heid1, K. Helbing5, H. Holvoet13, L. Van Hoorebeke13, N. Horikawa14, T. Iwata11, O. Jahn1, P. Jennewein1, T. Kageya14, B. Kiel5, F. Klein8, R. Kondratiev15, K. Kossert16, J. Krimmer9, M. Lang1, B. Lannoy13, R. Leukel1, V. Lisin15, T. Matsuda12, J.C. McGeorge4, A. Meier6, D. Menze8, W. Meyer6, T. Michel5, J. Naumann5, A. Panzeri2, 3, P. Pedroni2, T. Pinelli2, 3, I. Preobrajenski1, 15, E. Radtke6, E. Reichert17, G. Reicherz6, Ch. Rohlof 8, G. Rosner4, D. Ryckbosch13, M. Sauer9, B. Schoch8, M. Schumacher16, B. Seitz16, T. Speckner5, N. Takabayashi11, G. Tamas1, A. Thomas1, R. van de Vyver13, A. Wakai14, W. Weihofen16, F. Wissmann16, F. Zapadtka16 and G. Zeitler5
1 Institut für Kernphysik, Universität Mainz, D-55099 Mainz, Germany
2 INFN, Sezione di Pavia, I-27100 Pavia, Italy
3 Dipartimento di Fisica Nucleare e Teorica, Università di Pavia, I-27100 Pavia, Italy
4 Department of Physics & Astronomy, University of Glasgow, Glasgow G12 8QQ, UK
5 Physikalisches Institut, Universität Erlangen-Nürnberg, D-91058 Erlangen, Germany
6 Institut für Experimentalphysik, Ruhr-Universität Bochum, D-44801 Bochum, Germany
7 CEA Saclay, DSM/DAPNIA/SPhN, F-91191 Gif-sur-Yvette Cedex, France
8 Physikalisches Institut, Universität Bonn, D-53115 Bonn, Germany
9 Physikalisches Institut, Universität Tübingen, D-72076 Tübingen, Germany
10 Department of Physics, University of Lund, Lund, Sweden
11 Department of Physics, Nagoya University, Chikusa-ku, Nagoya, Japan
12 Faculty of Engineering, Miyazaki University, Miyazaki, Japan
13 Subatomaire en Stralingsfysica, Universiteit Gent, B-9000 Gent, Belgium
14 CIRSE, Nagoya University, Chikusa-ku, Nagoya, Japan
15 INR, Academy of Science, Moscow, Russia
16 II. Physikalisches Institut, Universität Göttingen, D-37073 Göttingen, Germany
17 Institut für Physik, Universität Mainz, D-55099 Mainz, Germany
arends@kph.uni-mainz.de
(Received: 19 December 2002 / Published online: 20 May 2003)
Abstract
The helicity dependence of the
reaction has been measured for the first time at a center-of-mass
angle
in the photon energy range from
780 MeV to 790 MeV. The experiment, performed at the Mainz
microtron MAMI, used a 4
-detector system, a circularly
polarized, tagged photon beam, and a longitudinally polarized
frozen-spin target. The helicity 3/2 cross-section is found to be
small and the results for helicity 1/2 agree with predictions
from the MAID analysis.
13.60.Le - Meson production.
14.20.Gk - Baryon resonances with S=0 .
25.20.Lj - Photoproduction reactions.
© Società Italiana di Fisica, Springer-Verlag 2003