## 3 Results and Discussion
### Pre-Dose Sensitization  
In the present investigation, the qualitative explanation suggested by [PERSON] was adopted in which a pre-dose heating treatment is given to the investigated sample. This treatment populates the reservoir centers with more holes. Consequently, these holes will relax to populate the centers responsible for emitting TL peaks. As the population of the recombination centers increases, the intensity of the TL glow peak is obviously enhanced. The physical mechanism underlying the per-dose sensitization can be qualitatively understood based on the effective regrouping of the occupancy level of various luminescent centers. Actually, regrouping of the luminescent centers enhances the charge relation responsible for producing the observed TL peak. The following steps show the procedure adopted for the activation dose protocol:  
(a) Aliquots were kept at 900 \({}^{\circ}\)C for 8 h; subsequently, the aliquots were given a test dose of 1 Gy (from this step, we aimed to find \(\mathbb{S}_{0}\));  
(b) The preceding series of aliquots were given a single pre-dose of \(\gamma\)-radiation varying between 0.1 kGy and 1.75 kGy;  
(c) After the first two steps, all the aliquots were heated to 500 \({}^{\circ}\)C, and (d) when cooled, a test dose (1 Gy) was given to the aforementioned heated aliquots that had sensitivity S. from these four steps we abled to report S/S\({}_{0}\). As shown in Figure 2a, in the beginning, the variation of the sensitivity is linear, but finally, near saturation of the pre-dose effect, a turnover is observed. This behavior occurs approximately at a dose with a value of 1.1 kGy of the applied pre-dose. Thermal sensitization: The thermal activation characteristic (TAC) was measured according to the following steps:  
Step 1. The aliquots (of the same weights) were kept at 900 \({}^{\circ}\)C for about 8 h, and then, an optimum pre-dose of 1 kGy were given such aliquots;  
Step 2. After finishing the previous step, these aliquots were heated in the range starting at 300 \({}^{\circ}\)C and ending at 700 \({}^{\circ}\)C;  
Step 3. After the aliquots were cooled, 1 Gy dose was applied to determine the parameter S. The S/S\({}_{0}\) was then computed at several temperatures (between 300 \({}^{\circ}\)C and 700 \({}^{\circ}\)C) (Figure 2b). For the investigated material (phyllite), 550 \({}^{\circ}\)C was found to be the optimal activation temperature, meaning that the maximum charge carrier concentration was reached. Figure 1: TL glow curve of the as-received sample. As is shown in Figure 2b, a clear increase in sensitivity is observed. At high temperatures, the thermal deactivation observed is explained using [PERSON]'s model, in which the second electron trap (T\({}_{2}\)) is thermally connected. Accordingly, the electrons existing in T\({}_{2}\) are thermally transferred into the conduction band, and the drop in sensitivity occurring above a certain temperature is attributed to the radiative recombination of the relaxed electrons moving away from T\({}_{2}\) with trapped holes. As depicted in Figure 3, the pre-dosed glow curves have three distinct peaks, observed at 75 \({}^{\circ}\)C, 115 \({}^{\circ}\)C, and 250 \({}^{\circ}\)C, respectively. The low-temperature peaks shown at 75 \({}^{\circ}\)C and 115 \({}^{\circ}\)C are thermally unstable. With an increase in pre-dose, they disappear, and a new peak is observed at 120 \({}^{\circ}\)C. The new peak is explained by the phenomenon of destruction and filling of different traps during the irradiation process. Figure 3: Variation of glow curves with the pre-dose. Figure 2: The sensitization factor of 250 \({}^{\circ}\)C TL peak of phyllite versus (**a**) pre-dose with \(\gamma\)-radiation and (**b**) post-irradiation temperature. In addition, as depicted in the glow curves, those that annealed at low temperatures 300-500 \({}^{\circ}\)C (Figure 4) have a new high-temperature peak at 315 \({}^{\circ}\)C, which completely disappears at higher temperatures.