Influence of target material impurities on physical results in relativistic heavy-ion collisions

This paper presents the studies on the influence of the target material impurities on physical observables registered in heavy ion collisions collected by fixed target experiments. It mainly concerns the measures of multiplicity fluctuations which can be used to searches for critical point of strongly interacting matter, e.g. in the {NA61/SHINE} fixed-target experiment at CERN SPS. The elemental composition of the targets used in the NA61/SHINE experiment was determined applying wavelength dispersive X-ray fluorescence (WDXRF) technique. The influence of measured target impurities on multiplicity distributions and scaled variance was estimated using simulation events. The modification of the standard analysis was proposed to reduce this influence.