Berlin 2005 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 31: Elektromagnetische und Hadronische Proben

HK 31.7: Talk

Tuesday, March 8, 2005, 18:00–18:15, TU MA004

Exclusive Measurements of the p^→p → ppπ⁺π⁻ Reaction at COSY-TOF^∗ — •A. Erhardt, K. Ehrhardt, K. Haug, 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, the delayed pulse technique has been utilized for a positive identification of π⁺ particles. The dominant part of the extracted data samples consists of completely measured four-prong events, i.e. exclusively measured events with four overconstraints each. The resulting differential spectra for invariant masses, angular distributions and analyzing powers will be presented and discussed with respect to σ meson production and/or Roper excitation and their decay. ^∗ supported by BMBF (06 TU 201), DFG (Europ. Graduiertenkolleg), FZ Jülich (FFE) and Landesforschungsschwerpunkt (Quasiteilchen)