  The condition and specific features of non-dipole regime of radiation is
discussed in connection with the results of recent CERN experiment NA63 on
measurement of radiation power spectrum of $149\,$GeV electrons in thin
tantalum targets. The first experimental detection of logarithmic dependence of
radiation yield from the target thickness is the conclusive evidence of the
effect of radiation suppression in a thin layer of matter, which was predicted
many years ago, and which is the direct manifestation of radiation of
relativistic electron with non-equilibrium own Coulomb field. The special
features of angular distribution of radiation and its polarization in a thin
target at non-dipole regime are proposed for a new experimental study.

Accelerator Physics;High Energy Physics - Experiment