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We analyze recent AMS-02 comic-ray measurements of Lithium, Beryllium, Boron,Carbon, Nitrogen and Oxygen. The emphasis of the analysis is on systematicuncertainties related to propagation and nuclear cross sections. To investigatethe uncertainties in the propagation scenario, we consider five differentframeworks, differing with respect to the inclusion of a diffusion break at afew GV, the presence of reacceleration, and the presence of a break in theinjection spectra of primaries. For each framework we fit the diffusionequations of cosmic rays and explore the parameter space with Monte Carlomethods. At the same time, the impact of the uncertainties in the nuclearproduction cross sections of secondaries is explicitly considered and includedin the fit through the use of nuisance parameters. We find that all theconsidered frameworks are able to provide a good fit. In particular, twocompeting scenarios, one including a break in diffusion but no reaccelerationand the other with reacceleration but no break in diffusion are both allowed.The inclusion of cross-section uncertainties is, however, crucial, to thisresult. Thus, at the moment, these uncertainties represent a fundamentalsystematic preventing a deeper understanding of the properties of CRpropagation. We find, nonetheless, that the slope of diffusion at intermediaterigidities is robustly constrained in the range $\delta\simeq0.45-0.5$ inmodels without convection, or $\delta\simeq0.4-0.5$ if convection is includedin the fit. Furthermore, we find that the use of the AMS-02 Beryllium dataprovides a lower limit on the vertical size of the Galactic propagation halo of$z_\mathrm{h}\gtrsim3$ kpc.

Implications of Lithium to Oxygen AMS-02 spectra on our understanding of cosmic-ray diffusion