Pitch-angle anisotropy and differential rigidity spectra of cosmic rays during GLE on May 2 and 6, 1998

Using data from the worldwide network of neutron monitors (39 stations) and the method of global spectrographic survey, we have studied pitch-angle anisotropy and differential rigidity spectra of cosmic rays during the ground level enhancements on May 2 and 6, 1998. We obtained differential rigidity spectra of solar cosmic rays in these events and determined the maximum rigidities to which protons accelerated. The maximum rigidities of accelerated protons during the ground level enhancements on May 2 was ~2.4; on May 6, ~1.8 GV. The revealed bidirectional pitch-angle anisotropy indicates that Earth was in the IMF loop structure during these events.