Comparison between different readout approaches for aluminum oxide radiophotoluminescent crystals

The radiophotoluminescence (RPL) from aluminum oxide doped with carbon and magnesium (Al2O3:C,Mg) was investigated using different readout approaches. The systems explore either the 620 nm (red) or the 335 nm (UV) excitation bands of the F2+(2Mg)F2+(2Mg) defects responsible for the RPL signal in Al2O3:C,Mg. For luminescence detection, we tested a photodiode and a fiber spectrometer. The results show that the RPL signal is linear over the dose range investigated (10 mGy–1 Gy). The systems based on UV excitation have a lower background compared to the system based on red excitation, resulting in a higher signal to background ratio. The data from the fiber spectrometer system was analyzed using the area or a curve fitting of the F2+(2Mg)F2+(2Mg) emission band. The curve fitting approach was able to better separate signal from background, allowing for higher signal to background ratios. The main challenge is to reduce the background signal contributed by instrumental background and background due to residual concentration of defects that could not be bleached.

► Al2O3:C,Mg RPL crystals were investigated for dosimetry applications.
► RPL response is linear over the dose range investigated (10–1000 mGy).
► UV excited RPL shows better signal-to-noise ratio.
► Background can be reduced using a spectrometer as read out device.
► Residual background is an obstacle for detecting low doses (<10 mGy).