Hard directional X-radiation emitted by a positron moving in a carbon nanotube

Considered in this paper is the radiation emitted by a relativistic positron propagating inside a single-layer carbon nanotube and interacting without delay with the screened charges of the nuclei of the carbon atoms. It is shown, for example, that a beam of positrons with an energy around 1 GeV and a divergence of some 10(-4) is captured by the carbon nanotube and emits hard X-quanta with an energy about 0.3-2 MeV in the direction of its propagation. The results obtained allow one to consider carbon nanotubes a new source of hard X-radiation.