The selective annealing of point defects with different activation energies was

studied by performing sequences of thermal treatments on γ-irradiated silica samples at 300 to 450C. The experiments showed that the dependence upon time of

the concentration of two irradiation-induced point defects in silica depended upon

the thermal history of the sample. These centres were ODC(II) (oxygen-deficient

centre II) and Eγ

’. In the long term, this concentration reached an asymptotic value

that depended only upon the treatment temperature. These results suggested the

existence of a distribution of activation energies for the reaction process that was

responsible for the annealing of the defects investigated and was closely related to

the intrinsic disorder of the amorphous lattice. The data also showed that heattreatment

could modify the distribution of activation energies and, consequently,

the thermal properties of the centre itself.

Annealing of Radiation Induced Oxygen Deficient Point Defects in Amorphous

Silicon Dioxide: Evidence for a Distribution of the Reaction Activation Energies.

L.Nuccio, S.Agnello, R.Boscaino: Journal of Physics - Condensed Matter, 2008,

20[38], 385215