The luminescence of Li 6(Gd,Y)(BO 3) 3:Ce fibers under intracenter photoexcitation, vacuum ultraviolet excitation and ultrasoft X-rays has been investigated. The performed study has revealed the following features: the intensive impurity luminescence is dominated in the photoluminescence spectra and excited efficiently in a wide range of excitation energies; an intense fast component of the luminescence decay kinetics in the subnanosecond range is due to the high local density of electronic excitations and the processes of Auger relaxation of the core hole.