One of the main goal of the COSY-11 collaboration is to study the eta meson interaction with nucleons and the mechanism of the eta production in different isospin channels. Over the last few years, we have performed several experimental investigations on the close to treshold eta production in nucleon-nucleon collisions using unpolarized as well as polarized beam. Experiments of the pp->ppeta, pd->pdeta, and pn->pneta are based on the four-momentum registration of outgoing nucleons and nuclei. eta meson is identified via the missing mass technique.
The internal facility COSY-11 [1] installed at the Cooler Synchrotron COSY [2] is shown in the figure below.
Results of the performed measurements and the details of the experimental method can be found in references [3].
Figure 1:
Scheme of the COSY-11 detection system.
Protons are registered in two drift chambers D1, D2 and in the
scintillator hadoscopes S1, S2, S3.
An array of silicon pad detectors (Sispec) is used
for the registration of the spectator protons.
Neutrons are registered in the neutron modular detector (N).
In order to distinguish neutrons from charged particles veto
detector is used. Deuterons are registered in deuteron
chamber D3.
[1] S. Brauksiepe et al., Nucl. Instr. & Meth. A 376
397-410 (1996)
[2] R. Maier, Nucl. Instr. & Meth. A 390 1-8 (1997)
[3] P.Winter et al., Phys.Lett. B 544 (2002) 251-258;
P.Moskal et al., Phys.Lett. B 517 (2001) 295-298;
P.Moskal et al., Phys.Lett. B 482 (2000) 356-362;
P.Moskal et al., Phys.Lett. B 474 (2000) 416-422;
J.Smyrski, Phys.Lett. B 474 (2000) 182-187;
P.Moskal et al., Phys.Lett. B 420 (1998) 211-216;
C.Quentmaier et al., Phys.Lett. B 515 (2001) 276-282;
M.Wolke et al., Nucl.Phys.News 9 (1999) 27-32;
S.Sewerin , Phys.Rev.Lett. 83 (1999) 2682-685;
J.Balewski et al., Eur.Phys.Jou. A 2 (1998) 1, 99-104;
J.Balewski et al., Phys.Lett. B 420 (1998) 211-216.
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