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

• Autor(a) principal: AMS collaboration (243 authors)
• Data de Publicação: 2018
• Outros Autores: Arruda, L., Barao, F., Orcinha, M.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.26/27698

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 ΦN can be presented as the sum of its primary component ΦNP and secondary component ΦNS, ΦN=ΦNP+ΦNS, and we found ΦN is well described by the weighted sum of the oxygen flux ΦO (primary cosmic rays) and the boron flux ΦB (secondary cosmic rays), with ΦNP=(0.090±0.002)×ΦO and ΦNS=(0.62±0.02)×ΦB 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.