COSMIC-RAY HELIUM HARDENING
COSMIC-RAY HELIUM HARDENING
Recent observations by the CREAM and ATIC-2 experiments suggest that (1) the spectrum of cosmic-ray (CR) helium is harder than that of CR protons below the knee energy, 1015eV, and (2) all CR spectra become hard at ≳1011eV nucleon−1. We propose a new idea, that higher energy CRs are generated …