  Hadron beams are invoked to explain the peculiar properties of a subclass of
BL Lac objects, the so-called extreme BL Lacs (EHBLs). This scenario predicts a
quite distinctive feature for the high-energy gamma-ray spectrum of these
sources, namely a hard energy tail extending up to $\sim100$ TeV. It has been
proposed that the detection of this tail can offer an unambiguous way to
distinguish between the hadron beam scenario and the standard one, which
instead assumes gamma-ray emission from the jet strongly depleted at the
highest energies ($E>30$ TeV) because of the interaction with the optical-IR
cosmic radiation field. We present dedicated simulations of observations
through the presently under construction Cherenkov Telescope Array (CTA) of the
very-high energy spectrum of the prototypical EHBL 1ES 0229+200 assuming the
two alternative models. We demonstrate that, considering 50 hours of
observations from the southern site of CTA (the most sensitive at the highest
energies), in the case of the hadron beam model it is possible to detect the
source up to 100 TeV. This, together with the non detection of the source above
10 TeV in the standard case, ensures that CTA observations can be effectively
used to unambiguously confirm or rule out the hadron beam scenario.
