Energy Spectrum of Cosmic Protons and Helium Nuclei by a Hybrid   Measurement at 4300 m a.s.l
  The energy spectrum of cosmic Hydrogen and Helium nuclei has been measured, below the so-called "knee", by using a hybrid experiment with a wide field-of-view Cherenkov telescope and the Resistive Plate Chamber (RPC) array of the ARGO-YBJ experiment at 4300 m above sea level. The Hydrogen and Helium nuclei have been well separated from other cosmic ray components by using a multi-parameter technique. A highly uniform energy resolution of about 25% is achieved throughout the whole energy range (100 TeV - 700 TeV). The observed energy spectrum is compatible with a single power law with index gamma=-2.63+/-0.06. 
B. Bartoli, P. Bernardini, X.J. Bi, I. Bolognino, P. Branchini, A.   Budano, A.K. Calabrese Melcarne, P. Camarri, Z. Cao, R....
astro-ph.HE hep-ex