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 [math] ^{137}Cesium[/math] 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, [math]{D}=(\text{Distance to faceplate} + 11.2cm)=41.2cm [/math] , the exposure rate is calculated in Roentgen using [math] \dot R = \frac {\Gamma A }{ D^2} [/math]. A gamma factor of [math] {\Gamma} = 0.33 \frac {(m^2)(R)}{(Ci)(hr)} [/math] and activity of [math]{A} = 9.3 Ci [/math] is used for these calculations. Using the exposure rate calculation, it is possible to find the total exposure by integrating over time, [math]\int\limits_{t_0}^{t_f}\dot R\ dt [/math].

Total exposures are calculated by

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Thesis