Angular distributions of high energy protons channeled in long (10,10) single-wall carbon nanotubes

In this work we study the angular distributions of 1 GeV protons channeled in long (10,10) single-wall carbon nanotubes. The nanotube length, L, is varied between 10 and 100 mu m. The angular distributions of channeled protons are obtained using the numerical solution of the proton equations of motion in the transverse plane and the Monte Carlo method. The effects of proton energy loss and scattering angle dispersion caused by its collisions with the nanotube electrons are taken into account. Analysis shows that for L LT 30 mu m, the transverse structure of the nanotube could be deduced from the angular distribution. For L GT = 40 mu m, the angular distribution contains the concentric circular ridges whose number increases and the average distance between them decreases when L increases. A possible application of the obtained results for characterization of carbon nanotubes is discussed