Hard X-radiation emitted by a charged particle moving in a carbon nanotube

We consider the radiation emitted by a charged particle propagating inside a single-layer carbon nanotube and interacting without delay with the screened charges of the nuclei of carbon atoms. It is shown, for example, that a beam of positrons with an energy of around 1 GeV and a divergence of some 10(-4) rad is captured by the nanotube and emits hard X-rays with an energy of about 0.3 MeV in the direction of its propagation. The theoretical results obtained allow one to consider carbon nanotubes as a new source of hard X-radiation.