  The influence of oxygen and carbon impurities on the concentrations of
defects in silicon for detector uses, in complex fields of radiation (proton
cosmic field at low orbits around the Earth, at Large Hadron Collider and at
the next generation of accelerators as Super-LHC) is investigated in the frame
of the quantitative model developed previously by the authors. The generation
rate of primary defects is calculated starting from the projectile - silicon
interaction and from recoil energy redistribution in the lattice. The
mechanisms of formation of complex defects are explicitly analysed.
Vacancy-interstitial annihilation, interstitial and vacancy migration to sinks,
divacancy, vacancy and interstitial impurity complex formation and
decomposition are considered. Oxygen and carbon impurities present in silicon
could monitor the concentration of all stable defects, due to their interaction
with vacancies and interstitials. Their role in the mechanisms of formation and
decomposition of the following stable defects: VP, VO, V_2, V_2O, C_i, C_iO_i
and C_iC_s is studied. The model predictions could be a useful clue in
obtaining harder materials for detectors at the new generation of accelerators,
for space missions or for industrial applications.
