Eur. Phys. J. A (2006) 30: 443-453
https://doi.org/10.1140/epja/i2006-10133-6

Hadron Physics

Single-pion production in pp collisions at 0.95 GeV/c (I)

¹ Ruhr-Universität Bochum, Germany
² Technische Universität Dresden, Germany
³ Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany
⁴ Forschungszentrum Jülich, Germany
⁵ Forschungszentrum Rossendorf, Germany
⁶ Physikalisches Institut der Universität Tübingen, Auf der Morgenstelle 14, D-72076, Tübingen, Germany
⁷ Sezione di Torino, University of Torino and INFN, Italy
⁸ Atomic Energy Authority NRC, Cairo, Egypt
⁹ Soltan Institute for Nuclear Studies, Warsaw, Poland

^* e-mail: clement@pit.physik.uni-tuebingen.de

Received: 10 July 2006
Accepted: 18 October 2006
Published online: 13 November 2006

Abstract

The single-pion production reactions pp → dπ⁺, pp → npπ⁺ and pp → ppπ⁰ were measured at a beam momentum of 0.95GeV/c ( T _p ≈ 400MeV) using the short version of the COSY-TOF spectrometer. The implementation of a central calorimeter provided particle identification, energy determination and neutron detection in addition to time-of-flight and angle measurements. Thus, all pion production channels were recorded with 1-4 overconstraints. The total and differential cross-sections obtained are compared to previous data and theoretical calculations. Main emphasis is put on the discussion of the ppπ⁰ channel, where we obtain angular distributions different from previous experimental results, however, partly in good agreement with recent phenomenological and theoretical predictions. In particular, we observe very large anisotropies for the π⁰ angular distributions in the kinematical region of small relative proton momenta revealing there a dominance of proton spinflip transitions associated with π⁰ s and d partial waves and emphasizing the important role of π⁰ d-waves.