On the motion of high-energy wave packets and the transition radiation by "half-bare'' electron

The problem of the motion of high-energy wave packets combined of free electromagnetic waves is considered. It is demonstrated that the transformation of such packets to the packet of spherically diverging waves happens on long distances along the packet’s motion direction, that substantially exceed the radiated wavelength. The transition radiation by the ``half-bare’’ ultrarelativistic electron is considered. It is demonstrated that the transition radiation by such an electron on the targets located inside and outside the coherence length of the radiation process would be substantially different.