Direct measurements of carbon, oxygen, and iron cosmic ray spectra from about 20 gigavolts to 100 teravolts (60 teravolts for iron) have been achieved using nine years of DAMPE satellite data, marking the first direct detection of charge-dependent spectral softenings for these species.

While the raw DAMPE data are not publicly accessible due to complexity and volume, the processed flux data are available in the supplementary information, and related data and code can be accessed on the Code Ocean platform.

When these spectra are combined with updated proton and helium measurements, they reveal a universal spectral softening at a rigidity around 15 teravolts, suggesting a common underlying mechanism across different nuclei.

The paper explores potential explanations for the observed features, including the influence of a nearby cosmic ray source and various propagation-related models.

Statistical analysis rejects a nuclei-mass-dependent softening with over 99.999% confidence, supporting a charge-dependent interpretation for the spectral breaks.