Precision Measurement of Cosmic-Ray Nitrogen and its Primary and Secondary Components with the Alpha Magnetic Spectrometer on the International Space Station

A precision measurement of the nitrogen flux with rigidity (momentum per unit charge) from 2.2 GV to 3.3 TV based on 2.2 ×10⁶ events is presented. The detailed rigidity dependence of the nitrogen flux spectral index is presented for the first time. The spectral index rapidly hardens at high rigidities and becomes identical to the spectral indices of primary He, C, and O cosmic rays above ∼700 GV . We observed that the nitrogen flux Φ_N can be presented as the sum of its primary component Φ_N^P and secondary component Φ_N^S, Φ_N=Φ_N^P+Φ_N^S, and we found Φ_N is well described by the weighted sum of the oxygen flux Φ_O (primary cosmic rays) and the boron flux Φ_B (secondary cosmic rays), with Φ_N^P=(0.090 ±0.002 )×Φ_O and Φ_N^S=(0.62 ±0.02 )×Φ_B over the entire rigidity range. This corresponds to a change of the contribution of the secondary cosmic ray component in the nitrogen flux from 70% at a few GV to <30 % above 1 TV.