  High-energy Li-Be-B nuclei in cosmic rays are being measured with unprecedent
accuracy by the AMS experiment. These data bring valuable information to the
cosmic ray propagation physics. In particular, combined measurements of B/C and
Be/B ratios may allow to break the parameter degeneracy between the cosmic-ray
diffusion coefficient and the size of the propagation region, which is crucial
for dark matter searches. The parameter determination relies in the calculation
of the Be and B production from collisions of heavier nuclei with the gas.
Using the available cross-section data, I present for the first time an
evaluation of the nuclear uncertainties and their impact in constraining the
propagation models. I found that the AMS experiment can provide tight
constraints on the transport parameters allowing to resolutely break the
degeneracy, while nuclear uncertainties in the models are found to be a major
limiting factor. Once these uncertainties are accounted, the degeneracy remains
poorly resolved. In particular, the Be/B ratio at ~1 - 10 GeV/n is found not to
bring valuable information for the parameter extraction. On the other hand,
precise Be/B data at higher energy may be useful to test the nuclear physics
inputs of the models.
