  We measured a considerable increase of the emitted radiation by 120 GeV/c
electrons in an axially oriented lead tungstate scintillator crystal, if
compared to the case in which the sample was not aligned with the beam
direction. This enhancement resulted from the interaction of particles with the
strong crystalline electromagnetic field. The data collected at the external
lines of CERN SPS were critically compared to Monte Carlo simulations based on
the Baier Katkov quasiclassical method, highlighting a reduction of the
scintillator radiation length by a factor of five in case of beam alignment
with the [001] crystal axes. The observed effect opens the way to the
realization of compact electromagnetic calorimeters/detectors based on oriented
scintillator crystals in which the amount of material can be strongly reduced
with respect to the state of the art. These devices could have relevant
applications in fixed-target experiments as well as in satellite-borne
gamma-telescopes.
