A spectrum of radially excited charmonium states is calculated for the model of relativistic spherically symmetric top for decay products. Within the integral formalism, the widths of these states are calculated for hadron resonance decay. Mass and width values obtained are in good agreement with the results of experiments. Six new radially excited charmonium states are predicted above the D\( \bar D \)-pair generation threshold equal to 3.73 GeV/s; three of them are experimentally confirmed. The possibility of application of antiproton beams with momentum from 1 to 15 GeV/s for charmonium spectroscopy is discussed, especially for masses exceeding the threshold of D\( \bar D \)-pair generation. The advantage of antiproton beams is that intensive generation of particle-antiparticle pairs is observed during antiproton-proton annihilation. This fact allows spectroscopic investigations to be performed with sufficient statistics and good accuracy. Therefore, masses and widths of scalar and vector charmonium states can be measured with high accuracy.