Tübingen 2003 – wissenschaftliches Programm

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HK: Physik der Hadronen und Kerne

HK 11: Poster-Sitzung: Elektromagnetische und hadronische Proben

HK 11.15: Poster

Dienstag, 18. März 2003, 13:30–15:30, Foyer

Cross Section Measurements of ω-Production in pn-Reactions — •I. Lehmann¹, S. Barsov², and R. Schleichert¹ — ¹Forschungszentrum Jülich — ²PNPI, Gatchina, Russia

ω-meson production has been investigated in pd→p_spdω reactions at the ANKE spectrometer at COSY-Jülich. Detection of slow spectator protons “p_sp” and fast deuterons are used to tag tag the reaction pn→dX. Measurements below and above the threshold for ω-production at four different proton beam energies allow to extract the ω-contribution from the missing mass distributions.

It is shown that a large background exists which can be described by two, three and four pion production. The cross section behaviour of these channels has been extrapolated from data on pp→dπ⁺π⁰, pp→dπ⁺π⁺π⁻ and pp→dπ⁺π⁺π⁻π⁰ reactions respectively. Adjusting these contributions at one beam energy, all other data can be described in a consistent way.

Moreover, for the Q-range interval from 42 to 78 MeV above threshold a signal for ω production is evident, which has been used to determine the total cross section of pn→dω. In the talk a comparison with model predictions and data from pp→ppω will be presented. Furthermore, the planned measurements for 2003 with an improved setup, that will refine the Q-binning and reduce uncertainties significantly, will be discussed.