Dear all; I'd like to inquire about the TL fading.
Usually the TL fading decreases by passing the days.
But based of the data that I got it, I found the fading is oscillated as in the attached file.
What is the physical explanation for that?
Thanks to all
Nidal Abahreh It is due to the different lifetimes of the Gd-Mg pairs and Gd-Mg-O triplets.
The graph you sent shows the TL response of 0.2 mol% Gd Mg doped SiO2 irradiated to 10 Gy dose of gamma irradiation over a period of 28 days.
The graph shows that the TL response decreases over time, but it does so in an oscillatory manner. The TL response reaches a peak on Day 1, then decreases on Day 7, then increases on Day 14, and so on. This oscillation continues until the TL response reaches a background level after about 28 days.
The oscillation in the fading curve is due to the different recombination rates of the Gd-Mg pairs and Gd-Mg-O triplets. The Gd-Mg pairs recombine more quickly than the Gd-Mg-O triplets, so the TL signal from the Gd-Mg pairs decays more quickly. This is why the TL response decreases on Day 7.
However, the Gd-Mg-O triplets also recombine eventually, so the TL signal from the Gd-Mg-O triplets begins to increase again. This is why the TL response increases on Day 14. The oscillation in the fading curve continues until all of the Gd-Mg pairs and Gd-Mg-O triplets have recombined and released their trapped electrons and holes. The oscillatory fading curve of Gd:Mg doped silica glass is a unique feature of this material. It can be used to distinguish Gd:Mg doped silica glass from other types of silica glass. It can also be used to study the recombination kinetics of the Gd-Mg pairs and Gd-Mg-O triplets.
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