## 3 Results
### Influence of Preheating before Readout on TL Signals and Signal Loss in Time  
#### 3.4.1 Influence of Preheating before Readout on TL Signals  
Because of the presence of large number of signals at lower temperatures, one can expect that the signal may be degraded during time due to the random recombinations and emission processes. After verification, this supposition was positively confirmed in experiment, whose results are shown further in Section 3.4.2.  
Thus, we decided to check the effect of preheating detectors prior to readout and its influence on the obtained TL curves. The preheating and TL signal stability experiments were performed on the PPG_Tb30 samples. Glass detectors were preheated directly before readout. Two temperatures were used for preheating, namely, 120 \({}^{\circ}\)C and 200 \({}^{\circ}\)C. The results of these experiments are presented in Figure 12. From the data presented in Figure 8, it is evident that preheating erases part of the TL signal, which cannot be obtained again. In case of the not preheated sample PPG_Tb30, at first sight one can observe three main peaks, at ca. 120 \({}^{\circ}\)C, 180 \({}^{\circ}\)C, and 260 \({}^{\circ}\)C. During preheating at 120 \({}^{\circ}\)C, two or even three low-temperature peaks, as presented in Figure 8b, are cleaned by emptying traps presented in the material. It is clear that removal of the lower temperature signals leads to situation, in which, after annealing, they do not contribute to the overall TL emission curve. Similarly, preheating to higher temperature of 200 \({}^{\circ}\)C consequently must lead to emptying of the five traps with lower energies existing in the material, as shown in Figure 8.  
Figure 12: TL curves for PPG_Tb30 samples irradiated using beta radiation (4 μs pulse duration), no preheating of detector, sample preheated at 120 \({}^{\circ}\)C, and at 200 \({}^{\circ}\)C; radiation dose applied ca. 30 kGy.  
The overall influence of the preheating procedure on the radiation dose and integrated TL intensity response is presented in Figure 13. Obviously, the TL signal integrals are more intensive for the non-preheated samples. This is a logical consequence of partial emptying of traps through preheating. Interestingly, preheating also has an influence on the dependencies of TL signal integrals vs. radiation dose absorbed. For the non-preheated samples, the dose response is of exponential character (saturation-type curve, triangles in Figure 13), for which signal saturation is observed above 15 kGy. For the sample preheated at 120 \({}^{\circ}\)C, the dose response is of linear character for lower dose range (up to 15 kGy), and for higher doses exhibits it exponential character (circles in Figure 13). Finally, after preheating at 200 \({}^{\circ}\)C, the presented in Figure 13 data representing the dependence of TL signal integral vs. dose absorbed remain linear even for the highest dose up to ca. 30 kGy. For comparison purposes, in Figure 13 both exponential fittings as well as linear approximations are shown for a clear presentation of the observed differences and effects of samples preheating at different conditions. After this analysis it is clear that preheating efficiently erases part of the lower energy traps, that, as one can observe, affects significantly the linearity of the dependence of integrated TL signal vs. radiation dose. With increasing of the absorbed dose, the low temperature defects saturate more effectively in comparison with those corresponding to higher temperatures. In such case, high-energy defects play a major role in TL signal generation.