The number of particles decreases more rapidly beyond a rigidity of about 15 TV, a phenomenon called spectral softening.
Cosmic Ray Mystery Solved: DAMPE Telescope Pinpoints “Spectral Softening”
The DAMPE space telescope, a collaborative project featuring contributions from the University of Geneva, has delivered a landmark finding in astrophysics. By analyzing the energy spectra of primary cosmic ray nuclei—ranging from protons to iron—the instrument has identified a universal behavior that challenges existing models of particle acceleration and transport.
The key discovery is a sharp "spectral softening" occurring at a rigidity of approximately 15 TV (teravolts). Beyond this threshold, the number of detected particles drops off far more rapidly than at lower energies. This pattern is not random; it is consistent across all particle types measured.
This result carries profound implications. It provides strong support for theoretical models in which both the acceleration of cosmic rays and their subsequent journey through the galaxy depend solely on a particle's rigidity (its momentum divided by charge). Critically, it rules out alternative theories that rely on energy-per-nucleon scaling.
The statistical confidence behind this conclusion is extraordinary. The analysis rejects energy-per-nucleon models with a confidence level of 99.999%.
The full findings have been published in the journal Nature, marking a significant step forward in our understanding of the most energetic particles in the universe.