  Boron K-edge soft x-ray emission and absorption are used to address the
fundamental question of whether divalent hexaborides are intrinsic semimetals
or defect-doped bandgap insulators. These bulk sensitive measurements,
complementary and consistent with surface-sensitive angle-resolved
photoemission experiments, confirm the existence of a bulk band gap and the
location of the chemical potential at the bottom of the conduction band.
