The thermoluminescence kinetics have been determined for the 13 glow peaks contained in the glow curves obtained from LiF TLD-100 after exposure to 60Co irradiations. The glow curves were constructed from measurements made with recently developed equipment for recording emission spectra at closely spaced temperature intervals. In addition, the recorded data has been subjected to all corrections needed to make it suitable for reliable kinetic analysis. The recorded emission spectra can be described by a single Gaussian-shaped band whose width and peak-energy parameters vary erratically with temperature or, alternatively, by resolving the observed spectra into three Gaussian-shaped bands whose parameters vary with temperatures in accord with theoretical expressions relating the emission-spectra peak energy and full width at half-maximum to the sample temperature. The kinetics and kinetic parameters were independently determined for the two most intense resolved emission bands. All peaks are described by first-order kinetics and the independently determined parameters are in very good agreement. The glow curves for the least intense component are also described by the same kinetics and parameters. Inasmuch as the single-band emission is a superposition of the three components, the same kinetics and parameters apply to the glow curve constructed from unresolved spectra. The identification number, nominal peak temperature in °C (for a heating rate of 10.3 °C/min), the activation energy E (eV), and preexponential factor s (sec−1) for the 13 peaks are as follows: (1) 1.62, 1.04, and 1014; (2) 94, 1.07, and 1013; (3a) 112, 0.987, and 1011; (3) 137, 1.05, and 1011; (4) 170, 1.54, and 4×1015; (5) 190, 2.20, and 1022; (5a) 210, 1.61, and 1015; (6) 235, 1.70, and 1015; (7) 260, 1.79, and 1015; (8) 285, 1.96, and 5×1015; (9) 315, 2.10, and 1016; (10) 345, 2.19, and 1016; (11) 370, 2.27, and 1016. The unusual value of s=1022 for the 190 °C peak, previously reported by other authors, was obtained during this study. However, it appears that this value can be obtained from relatively simple mechanisms and one of these is described.

The thermoluminescence of LiF TLD-100 dosimeter crystals has been studied using recently developed equipment for determining simultaneously the emission intensity and the emission spectrum as a function of sample temperature. Measurements were made on numerous samples exposed to 60Co irradiations at room temperature and at exposures varying from 500 to 3×107 R. Spectra were obtained at 1.38 and 5.5 °C intervals over the temperature range 20–350 °C. Below 105 R the thermoluminescent emission can be described by a single Gaussian-shaped band whose peak energy and full width vary irregularly with temperature and not in accord with the well-known expressions, given in the text, relating the emission-spectra peak energy and full width at half-maximum to the sample temperature. However, the emission is accurately described by three Gaussian-shaped bands whose approximate peak energies and full widths are 3.01, 0.90; 2.90, 0.72; and 2.71, 0.96 eV. The peak energies and full widths of these three bands vary with temperature in the expected manner. In addition to these bands, comparatively low-intensity bands are observed at exposures above 105 R at approximately 4.0, 2.98, 2.50, and 2.3 eV, with the possibility of another band at roughly 1.5 eV. The recorded data for each emission band was subjected to all corrections required to obtain glow curves which are strictly proportional to the number of processes occurring per unit time. In other words, the corrected glow curves are as free as possible of the systematic errors which might render them unsuitable for determining the kinetics. The glow curves extend from room temperature to 350 °C and contain nine prominent glow peaks. Below approximately 80 °C, the emission is confined to the 2.71-eV band. Above approximately 200 °C, the emission is confined to the 3.01-eV band. All three prominent emission bands contribute to the intermediate-temperature glow peaks. With increasing dose, the low-temperature peaks progressively diminish in intensity and the emission shifts to the higher-temperature peaks.

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The unusually complex thermoluminescence obtained from Harshaw dosimeter type TLD-100 LiF crystals has been studied with apparatus for measuring emission intensity simultaneously as a function of both wave length and sample temperature. A separate signal aver aged spectrum is obtained at 5.5 C temperature intervals. Data reduction includes all corrections needed to ob tain curves of absolute, intensity vs photon energy. Numerous results were obtained from crystals exposed to ç o 60 gamma-ray doses extending from 5 x 10^ to 5 x 10?R. All emission spectra could be resolved into Gaussian shaped bands using a computerized best-fit procedure. Below 10^ R all spectra contain three bands at roughly 3.01, 2.90, and 2.71 eV with full widths of 0.90, 0.72, and 0.96 eV; the precise values vary slightly with temperature. Above 10^ R additional bands appear at 2.98 and 2.50 eV, and with increasing exposure the 2.90 and 2.71 eV bands diminish in intensity. At doses greater than 4 or 5 x 10 6 R additional bands appear at 4.0, 2.3, and 1.5 eV. In the range usually used for dosimetry, at least the 3 bands at 3.01, 2.90, and 2.71 eV contribute to the thermoluminescence. Glow curves for each of these emission bands were construct ed from the resolved Gaussian shaped bands. They contain 8, 3, and 5 prominent peaks. In contrast, glow curves for unresolved spectra contain at least 8 glow peaks, and each peak can contain undetermined contributions from 1, 2, or 3 emission centers. All glow peaks analyzed to date can be fitted by the firstorder expression dn/dt = -ns exp (-E/kT). However, the E and s values obtained for the 190 C peak and perhaps some of thè other high temperature peaks are too large to be meariingful; thus the kinetics for this peak, and possibly other high temperature peaks, must be complex. To date, thirteen glow peaks have been identified. At low doses the emission is confined to the low temperature glow peaks. With increasing dose the emission intensity increases and progressively shifts to higher temperature peaks. The maximum inten sity occurs at 10^ R. At higher doses the emission is reduced but occurs among the highest temperature peaks.

The radiation-induced absorption of a group of barium aluminoborate glasses was studied in a new facility for measuring optical absorption during irradiation with y-rays. The results demonstrate that this technique provides significant new information on the kinetics of the radiation-induced coloring of glasses and suggest that most previous measurements are, at best, suspect. Barium aluminoborate glasses, both with and without Ce, were prepared under normal and reducing conditions. The coloring during irradiation and the decay after irradiation can be characterized by the absorption at 3.0 eV and at 2.25 or 1.90 eV. The Ce-free base glass continued to color as long as irradiated and, at a given dose, the absorption was at least 2 or 3 times that of the other glasses. The totally reduced 1% Ce glass colored to a constant level in the uv, but in the visible the coloring increased to a maximum and then decreased to a constant value. The partially reduced 1% Ce glass also colored to a constant value in the uv, but in the visible the original absorption decreased slightly. All the coloring curves recorded during irradiation are described accurately by expressions that include one or more increasing saturating exponential terms and may contain one linear or one decreasing saturating exponential term. After irradiation the coloring curves decrease and can be resolved accurately into one or more decreasing exponential components. Futhermore, all the observed coloring-curve features were derived from relatively simple kinetics.