Energy dependence of the near-threshold total cross-section for the pp -> pp eta ' reaction

Total cross sections for the pp --> pp eta' reaction have been measured in the excess energy range from Q = 1.53 MeV to Q = 23.64 MeV. The experiment has been performed at the internal installation COSY-11 [1] using a stochas tically cooled proton beam of the COoler SYnchrotron COSY [2] and a hydroge n cluster target [3,4]. Thr determined energy dependence of the total cross section weakens the hypothesis of the S-wave repulsive interaction between the eta' meson and the proton [5,6]. New data agree well with predictions based on the phase-space distribution modified by the proton-proton final-s tate-interaction (FSI) only. (C) 2000 Published by Elsevier Science B.V. Al l rights reserved.