Cgs. Costa et al., COMPOSITION OF PRIMARY COSMIC RAYS BEYOND THE KNEE FROM EMULSION CHAMBER OBSERVATIONS, Physical review. D. Particles and fields, 54(9), 1996, pp. 5558-5562
We show that the simplest assumptions for the dynamics of particle pro
duction allow us to understand the fluxes of hadrons and photons at mo
untain altitudes as well as the structure of individual events. The. a
nalysis requires a heavy nuclear component of primary cosmic rays abov
e the ''knee'' in the spectrum with an average mass number [A] = 7.3+/
-0.9.