[en] Determination of homogeneity of particle beam of (ΔE) accelerated in the electrostatic accelerator of Van de Graaff type is described. This value was calculated by measuring an yield of γ-quanta for resonance reactions of (p,γ) and (p,αγ) types on ¹⁹F, ²⁷Al, ¹³C, ⁵⁸Ni nuclei. Based on experimental data of the yield curve on a thick target, an experimental width for GITA level was estimated, which was identified by the comparison to calculated earlier functions GITA=f(ΔEsub(p)) for a given reaction. These calculations were performed by evaluating a resonance form taking into account a final resolution experimental facilities. The paper presents tables and graphs for expected dependences of GITA=f(ΔEsub(p)) for the mentioned resonance reactions