Observation of New Properties of Secondary Cosmic Rays Lithium, Beryllium, and Boron by the Alpha Magnetic Spectrometer on the International Space Station

Abstract

We report on the observation of new properties of secondary cosmic rays Li, Be, and B measured in the rigidity (momentum per unit charge) range 1.9 GV to 3.3 TV with a total of 5.4×10^{6} nuclei collected by AMS during the first five years of operation aboard the International Space Station. The Li and B fluxes have an identical rigidity dependence above 7 GV and all three fluxes have an identical rigidity dependence above 30 GV with the Li/Be flux ratio of 2.0±0.1. The three fluxes deviate from a single power law above 200 GV in an identical way. This behavior of secondary cosmic rays has also been observed in the AMS measurement of primary cosmic rays He, C, and O but the rigidity dependences of primary cosmic rays and of secondary cosmic rays are distinctly different. In particular, above 200 GV, the secondary cosmic rays harden more than the primary cosmic rays.

Deciphering the Local Interstellar Spectra of Secondary Nuclei with the Galprop/Helmod Framework and a Hint for Primary Lithium in Cosmic Rays

“…Other discrepancies, such as those reported in Figure 5 for beryllium, boron, and nitrogen when comparing to the HEAO-3 data (Engelmann et al 1990), are an indication of the systematic uncertainties of the instrument. This is demonstrated by the excellent agreement of spectra of boron and nitrogen with AMS-02 data (Aguilar et al 2018b) in the whole energy range from 2 GV -2 TV.…”

“…For our case this means that there is a source of primary lithium and that this lithium may be observed in CRs for the first time, thanks to the high statistics and precision achieved by the AMS-02 experiment (Aguilar et al 2018b). Though the absolute mass of lithium produced by novae is relatively small, the lithium abundance of the ejecta is comparable to that found in CRs given that the total mass of the ejecta is 10 −5 M − 10 −4 M .…”

“…A subsequent release of the spectra of other primary and secondary species by AMS-02 was eagerly awaited. First, AMS-02 confirmed a clear distinction in the rigidity dependencies between the groups of mostly primary nuclei, He, C, O (Aguilar et al 2017), and secondary nuclei, Li, Be, B (Aguilar et al 2018b), while the nuclei within each group have similar spectra. Nitrogen that is half-primary/halfsecondary fell in between (Aguilar et al 2018c).…”

“…Our model calculations of CR lithium (in the I-scenario) as compared to the AMS-02 data(Aguilar et al 2018b). Black dot-dashed line shows only secondary component.…”

High-Energy Particles and Radiation in Star-Forming Regions

“…The resulting level of field amplification and, as a consequence, the resulting maximum achievable energy, depends on the efficiency of particle acceleration and on the particle spectrum . Recent evidence suggests that the latter must be steep: this inference comes both from gamma-ray observations of SNRs and from models of CR propagation through the Galaxy, supplied with the findings by AMS-02 (Aguilar et al 2016(Aguilar et al , 2018 about the slope of the diffusion coefficient (see e.g. Amato and Blasi (2018) for a review).…”