Detecting Alpha Particles through Scintillation In Porous Materials

This thesis presents the results of a preliminary study of parameters essential to the development of a scintillation flow-cell detector with improved characteristics over existing cells. Such a detector with better than 10% alpha energy resolution could provide in situ capability to detect and identify important alpha-emitting radionuclides in dilute aqueous solutions. Gel-silica is a potential candidate that may provide the needed improvement in resolution while maintaining 100% detection efficiency; however, gel-silica with useful light output is yet to be developed. As a step toward realizing the system described, the dependence of alpha detection efficiency and intrinsic energy resolution on the phase dimensions in heterogeneous scintillation detectors is examined. Two main areas of this research are: (1) computer modeling of the geometric detection efficiency and intrinsic energy resolution in porous glass scintillation detectors, and (2) experiments designed to test model predictions and provide data on the detection of alphas in porous glass structures. Experimental emphasis is on alpha detection in gel-silica filled with liquid scintillant. Results show that phase dimensions must be considered in constructing a flow-cell detector for alpha spectroscopy, and that the dimensions available in gel-silica provide for excellent intrinsic energy resolution, as well as 100% detection efficiency