  Employing strong electrostatic gating (liquid-ion gating), the position of
the Fermi energy E_F (relative to the charge-neutrality point) was determined
in multi-wall carbon nanotubes (MWNTs). E_F is negative (hole doping) and
amounts to \approx -0.3 eV for MWNTs in air. Evidence that water, and not
oxygen, is the main source of doping has been found. As a consequence, the
number M of occupied 1d-modes (not counting spin) is >2, i.e. M \approx 10.
This is supported by the single-electron level spacing, deduced from observed
single-electron charging effects (SET) at low temperature. The latter are
dominated by co-tunneling processes, as we observe the Kondo effect. This
provides evidence, that highly transmissive channels are present in MWNTs at
low temperature, despite the `disorder' observed in previous experiments.
