Abstract
A precision measurement of the nitrogen flux with rigidity (momentum per unit charge) from 2.2 GV to 3.3 TV based on 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 . We observed that the nitrogen flux can be presented as the sum of its primary component and secondary component , , and we found is well described by the weighted sum of the oxygen flux (primary cosmic rays) and the boron flux (secondary cosmic rays), with and 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 above 1 TV.
- Received 16 April 2018
- Revised 6 June 2018
DOI:https://doi.org/10.1103/PhysRevLett.121.051103
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society