Köln 2004 – wissenschaftliches Programm

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HK: Physik der Hadronen und Kerne

HK 11: Poster Session: Electromagnetic and Hadronic Probes

HK 11.12: Poster

Dienstag, 9. März 2004, 13:30–15:30, Foyer

Total cross section for η production in the quasi-free pn→ pnη reaction — •M. Janusz — Institute of Physics, Jagellonian University, Cracow, PL-30-059, Poland

The comparison of the total cross sections for the η and η^′ meson production in the p-n and p-p collisions may be a proper tool in studying structure and production mechanism of both mesons.

The value of the total cross section for the reaction pp→ ppη was found to be about 6.5 times smaller than that for the pn→ pnη rection [1] which is explained by a dominant isovector meson (π , ρ) exchange. The corresponding ratio for the η^′ production will yield information of the underlying reaction mechanisms which are mediated by the η^′ structure. A feasibility study of the quasi-free pn→ pnη reaction has been carried out at the COSY-11 facility at the cooler synchrotron COSY in Jülich using a proton beam scattered at a deuteron cluster target [2]. The data are still under evaluation but clearly demonstrate the possibility to reconstruct quasi-free pn reactions at COSY-11. Similar investigations for the production of the η^′ meson have started. First measurements have been performed and a production run is scheduled for summer 2004 [3].

The detection capabilities of the quasi-free pn→ pnη (η^′) reaction at COSY-11 as well as preliminary results in the η channel will be presented.

[1] H. Calén et al., Phys. Rev. C 58 (1998) 2667.

[2] P. Moskal et al., nucl-ex/0311003.

[3] P. Moskal, COSY Proposal No.133.
Supported by Forschungszentrum Jülich.