INDEX radiation-induced

The exposure scenario described in the previous example of domestic uranium mill tailings was used to classify the high-radium residues. The risk and dose assessments indicated a probability of radiation-induced cancer incidence of about 0.6, potential doses in excess of 10 Sv, and a risk index between 50 and 100. Thus, these residues would be classified as high-hazard waste, even under conditions of perpetual institutional control over near-surface disposal sites, and they would require some form of greater confinement disposal well below the ground surface. This conclusion is consistent with recommendations for disposition of these residues (NAS/ NRC, 1995b). 

Vitreous silica has a unique set of properties. It is produced either from natural quartz by fusion or, if extreme purity is required, by chemical vapor deposition or via a sol-gel routes. Depending on the manufacturing process, variable quantities impurities are incorporated in the ppm or ppb range, such as Fe, Mg, Al, Mn, Ti, Ce, OH, Cl, and F. These impurities and radiation-induced defects, as well as complexes of impurities and defects, and also overtones, control the UV and IR transmittance. In the visible part of the spectrum, Rayleigh scattering from thermod)uiamically caused density fluctuations dominates. Defects are also responsible for the damage threshold under radiation load, and for fluorescence. The refractive index n and the absorption... 

The effect of electromagnetic radiation on matter is to induce a dipole. In a transparent dielectric medium, only the velocity of electromagnetic radiation is reduced, depending on the refractive index of the medium, which is determined by its density. The propagation constant of electromagnetic waves is given by... 

The real and imaginary parts of the refractive index n quantify the scattering and absorption (or amplification) properties of a material- The refractive index is besfl derived from the susceptibility tensor y of the material, defined below, whi j describes the response of a macroscopic "system to incident radiation [212], Spe fically, an incident electric field E(r, t), where r denotes the location in the medium, tends to displace charges, thereby polarizing the medium. The change in dmd(r, the induced dipole moment, from point r to point r + dr is given in terms of th polarization vector P(r, t), defined as... 

Ferroelectric lithium niobate (LiNbOs) has been of considerable interest because of its nonlinear optical properties. Conversion of infrared into visible radiation in LiNb03 crystals has been observed (Midwinter and Warner, 1967 Arutyunyan and Mkrtchyan, 1975). Electro-optic coefficients of LiNbOs have been determined for a wide range of frequencies ranging from the visible (Smakula and Claspy, 1967) to the millimeter-wave portion of the spectrum (Vinogradov et al., 1970). Other nonlinear optical properties such as photovoltaic effects (Kratzig and Kurz, 1977) and optically induced refractive index changes (Ashkin et al., 1966 Chen, 1969) have also been observed. 

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