Precise measurement of the total width of the η' meson

The physics of the η' meson receives an increasing interest in view of the forthcoming measurements planned e.g. at the COSY, DAφNE-2 and MAMI-C facilities where the η' will be produced in hadron-hadron, e+-e-, and γ-hadron reactions, respectively. Therefore, a precise determination of the natural line width of the η' (Γη') meson will have a strong impact on the physics results which will be derived from future measurements at the detector setups like e.g. WASA-at-COSY and KLOE. Among the only two previous direct measurements of Γη' the one performed by the NIMROD collaboration extracted the width of the η' meson with the smallest error Γη' = 0.28 ± 0.1 MeV. At the COSY-11 facility, combined with the excellent features of the COSY proton beam, the natural width of the η' meson can be determined with at least five times better precision due to better experimental resolution, larger statistics, better signal to background ratio, and finally due to a simultaneous use of two independent methods for the derivation of the width of the η' meson. The experimental method used and preliminary results of the ongoing analysis will be presented and discussed. (orig.)