Isospin dependence of the eta prime meson production in nucleon-nucleon   collisions
  A comparison of the close-to-threshold total cross section for the eta prime production in pp --> pp eta prime and pn --> pn eta prime reactions constitutes a tool to investigate the eta prime meson structure and the reaction mechanism in the channels of isospin I=0 and I=1 and may provide insight into the flavour-singlet (perhaps also into gluonium) content of the eta prime meson. In this contribution we present preliminary results of measurement of the quasi-free production of the eta prime meson in the proton-neutron collisions conducted using the COSY-11 facility. 
J.Przerwa, P.Moskal, A.Budzanowski, E.Czerwinski, R.Czyzykiewicz,   D.Gil, D.Grzonka, L.Jarczyk, T.Johansson, B.Kamys, A.Kho...