It is proposed to investigate the structure of the eta' meson by comparing its close to threshold production cross section in the proton-proton and proton-neutron interaction. The comparison of the ratio Reta' =sigma(pn->pn eta')/sigma(pp->pp eta') with Reta =sigma(pn->pn eta)/sigma(pp->pp eta) will allow to infer about the gluonium content of the eta' meson and the relevance of quark-gluon degrees of freedom when considering the close to threshold production of this meson.
In the extreme case when the eta' meson is created only from glue being excited in the interaction region the ratio Reta' should be close to unity after the correction for the final and initial state interaction between the interacting nucleons. Whereas a production mechanism dominated by the isovector meson exchange would yield a significantly larger ratio. In the latter case it is expected to be close to a value of 6.5 as already determined for the eta meson production.
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