Average ion intensity spectrum of the 11–13 December 2020 solar particle event measured with all sunward-facing sensors of the EPD suite. The shown ion data products of SIS and HET contain only protons while for STEP and EPT also heavy ion species contribute to the measured intensity in the magnet channels with an estimated relative contribution on the order of 10% for this event (see text for details). Panel a: measured ion intensity spectrum averaged over the two-day event period of 11–13 December represented by the filled symbols and also a quiet-time spectrum averaged over 7–12 November marked with the empty symbols (and labeled as “qt”). This quiet-time spectrum is subtracted from the measured spectrum to derive the quiet-time-corrected event spectrum in panel b, labeled as “qt-sub”. Panel c: quiet-time-corrected spectra are multiplied with the square of the primary energy for a better visualization of the differences between the different sensor spectra. The differences between the EPT and SIS measurements, as well as the ones between the HET-B and HET-C protons, are discussed in the text.