Precision Measurement of Cosmic-Ray Nitrogen and its Primary and Secondary Components with the Alpha Magnetic Spectrometer on the International Space Station
Name
PhysRevLett.121.051103.pdf
Size
359.46 KB
Format
Adobe PDF
Checksum (MD5)
84f2673db08d36e5def9120e2176836a
Author(s)
Aguilar, M.
Ali Cavasonza, L.
Alpat, B.
Ambrosi, G.
Arruda, L.
Attig, N.
Aupetit, S.
Azzarello, P.
Bachlechner, A.
Barao, F.
Date Issued
July 2018
Journal
Physical Review Letters
Publisher
American Physical Society
Citation
Aguilar, M. et al. Physical Review Letters 121, 5 (July 2018): 051103
Version
Final published version
Abstract
A precision measurement of the nitrogen flux with rigidity (momentum per unit charge) from 2.2 GV to 3.3 TV based on 2.2×10[superscript 6] 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[subscript N] can be presented as the sum of its primary component Φ[subscript N][superscript P] and secondary component Φ[subscript N][superscript S], Φ[subscript N] = Φ[subscript N][superscript P]+ Φ[subscript N][superscript S], and we found Φ[subscript N] is well described by the weighted sum of the oxygen flux Φ[subscript O] (primary cosmic rays) and the boron flux Φ[subscript B] (secondary cosmic rays), with Φ[subscript N][superscript P] = (0.090±0.002) × Φ[subscript O] and Φ[subscript N][superscript S] = (0.62±0.02) × Φ[subscript 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.
MIT Department
Massachusetts Institute of Technology. Department of Nuclear Science and Engineering
Massachusetts Institute of Technology. Department of Physics
Massachusetts Institute of Technology. Laboratory for Nuclear Science
Terms of Use
Creative Commons Attribution
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1103/PhysRevLett.121.051103
