Most interesting result at variance with the current knowledge:
“These findings suggest that the knee observed in the all-particle spectrum corresponds to the knee of the light component, rather than the medium-heavy components.
“
https://physics.aps.org/articles/pdf/10.1103/Physics.17.s39
https://journals.aps.org/prl/pdf/10.1103/PhysRevLett.132.131002