  A new analysis of cosmic ray (CR) data collected by the SOKOL experiment in
space found that the deuteron-to-helium ratio at energies between 500 and 2000
GeV/nucleon takes the value d/He ~ 1.5. As we will show, this result cannot be
explained by standard models of secondary CR production in the interstellar
medium and points to the existence of a high-energy source of CR deuterons. To
account for the deuteron excess in CRs, we argue that the only viable solution
is hadronic interaction processes of accelerated particles inside old supernova
remnants (SNRs). From this mechanism, however, the B/C ratio is also expected
to increase at energy above ~50 of GeV/nucleon, in conflict with new precision
data just released by the AMS-02 experiment. Hence, if this phenomenon is a
real physical effect, hadronic production of CR deuterons must occur in SNRs
characterized by low metal abundance. In such a scenario, the sources
accelerating C-N-O nuclei are not the same as those accelerating helium or
protons, so that the connection between d/He ratio and B/C ratio is broken, and
the latter cannot be used to place constraints on the production of light
isotopes or antiparticles.
