  We report cross sections for the direct excitation of gamma-ray transitions
up to 200 keV by the transient electromagnetic fields of electrons from a beam,
for incident kinetic energies of 500 keV and 5 MeV. The cross sections for the
electron activation of gamma-ray fluorescence are of the order of 300 nanobarns
for an electron incident kinetic energy of 500 keV, and are of the order of 10
microbarns for an electron incident kinetic energy of 5 MeV. The electron
excitation of nuclear transitions may lead to the development of pulsed sources
of gamma radiation of narrowly defined energy.
