Köln 2004 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 27: Electromagnetic and Hadronic Probes IV

HK 27.5: Talk

Wednesday, March 10, 2004, 12:00–12:15, E

Exclusive Measurements of the p^→p → ppπ⁺π⁻ Reaction at COSY-TOF^∗ — •A. Erhardt, J. Kress, H. Clement, E. Doroshkevich, and G.J. Wagner — Physikalisches Institut, Universität Tübingen

By use of the COSY vector polarized proton beam the p^→p → ppπ⁺π⁻ reaction has been measured at COSY-TOF at two different energies, T_p = 750 and 800 MeV, i.e. close to threshold. Time-of-flight information and track reconstruction has been obtained by use of the informations supplied by start, fiber, quirl and ring hodoscopes, whereas particle identification and energy information has been provided by the central calorimeter. In addition, delayed pulse technique has been utilized for a positive identification of π⁺ particles. The dominant part of the extracted data samples consist of completely measured 4 prong events, i.e. exclusively measured events with 4 overconstraints each. This way very clean data have been obtained. The resulting differential spectra for invariant masses, angular distributions and analyzing powers will be presented and discussed with respect to model calculations for σ meson production and/or excitation and decay of the Roper resonance. ^∗ supported by BMBF (06 TU 201), DFG (Europ. Graduiertenkolleg), FZ Jülich (FFE) and Landesforschungsschwerpunkt (Quasiteilchen)