[en] Thermally stimulated currents (TSC) of γ irradiated poly(methyl methacrylate) thermoelectrets have been investigated in the high-temperature range. The two main peaks of the TSC spectrum, appearing, respectively, at about 100 (α) and 120⁰C (rho), show marked differences in stability under iradiation: while the α peak is little affected by doses up to 10⁷ rad, the rho peak vanishes following doses of 10⁵ to 10⁶ rad. On the other hand, a study of the rate of decrease of the rho peak as a function of irradiation conditions reveals the important role of the surrrounding atmosphere and the existence of a flux effect, probably related to irradiation-accelerated diffusion of gas into the polymer. All these facts confirm the respective attributions of α and rho peaks to a dipolar volume polarization and to an ionic space charge polarization, showing that the TSC study of irradiated thermoelectrets can be a useful method for identification of polarization processes in polymers

[en] Lyoluminescence (LL) of several carbohydrates and amino acids has been measured in water for a γ dose of respectively, 20 Gy and 50 Gy. It has been demonstrated that the LL yield depends markedly not only on the nature of the LL material but also on its commercial origin. By using solutions of organic dyes such as eosin B, rhodamine B or fluorescein, a substantial enhancement of LL has been observed with carbohydrates. Concentration effect has been investigated and maximum LL yields have been observed in the range 10^-5-10^-4 mol. On the other hand, LL of amino acids has been increased by the use of rare earth ion solutions. Dysprosium, europium and terbium solutions have been used, but it has been proved that terbium nitrate is the most appropriate solution. Concentration effect has been studied for several amino acids and dosimetric response of glutamine has been investigated with different rare earth ions solutions. (Author)

[en] Lyoluminescence of glutamine, serine, arginine · HCl, lysine · HCl, inositol and mannose has been investigated. It has been demonstrated that the commercial origin of the sample plays an important role in the LL response. Recrystallization enhances the LL signal of the less sensitive mannose samples and reduces the dispersion of LL yields. Differences resulting from the nature and concentration of radiation-induced free radicals and from the grain size distribution cannot explain the LL variability and the change of LL yield after recrystallization. Supposed effects of water or solvent retention and traces of impurities are discussed. (author)

[en] Lyoluminescence of various saccharides and of glutamine has been investigated by using a home made read-out system allowing a better control of the dissolution rate. The device has been tested by measuring the weight and dose dependence of D(+) mannose and the influence of the origin of the sample. The use of eosin B solutions as a solvent shows a substantial enhancement of lyoluminescence for dextrose and xylose. (author)