  The irradiation represents a useful tool for determining the characteristics
of defects in semiconductors as well as a method to evaluate their degradation,
fact with important technological consequences. In this contribution, starting
from available data on the degradation of silicon detector characteristics in
radiation fields, these effects are explained in the frame of a model that
supposes also the production of the SiFFCD defect due to irradiation. The
displacement threshold energies - different for different crystallographic
axes, considered as parameters of the model, are established and the results
obtained could contribute to clarify these controversial aspects. Predictions
of the degradation of electrical parameters (leakage current, effective carrier
concentration and effective trapping probabilities for electrons and holes) of
DOFZ silicon detectors in the hadron background of the LHC accelerator,
supposing operation at -10 grdC are done. The non uniformity of the rate of
production of primary defects and of complexes, as a function of depth, for
incident particles with low kinetic energy was obtained by simulations in some
particular and very simplifying assumptions, suggesting the possible important
contribution of the low energy component of the background spectra to detector
degradation.
