Calibration Info

To fully understand the relationship between PMT Counts and total exposure for the Nanodot OSLs, a custom calibration is needed. This calibration is used in lieu of the calibration created by the OSL reader, which is created using the pre-dosed OSLs from the manufacturer. To begin the calibration, a set of fifteen unexposed Nanodot OSLs is chosen at random and exposed to a 9.3Ci $^{137}Cesium$ source. Using a distance of 30cm from the faceplate of the source and also including the distance from the faceplate to the surface of the source, ${D}=(\text{Distance to faceplate} + 11.2cm)=41.2cm$ , the exposure rate is calculated in Roentgen using $\dot R = \frac {\Gamma A }{ D^2}$. A gamma factor of ${\Gamma} = 0.33 \frac {(m^2)(R)}{(Ci)(hr)}$ and activity of ${A} = 9.3 Ci$ is used for these calculations. Using the exposure rate calculation, it is possible to find the total exposure by integrating over time, $\int\limits_{t_0}^{t_f}\dot R\ dt$.

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Thesis