Date of Award

Fall 12-2018

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

School

Mathematics and Natural Sciences

Committee Chair

Chris Winstead

Committee Chair School

Mathematics and Natural Sciences

Committee Member 2

Khin Maung Maung

Committee Member 2 School

Mathematics and Natural Sciences

Committee Member 3

Jeremy Scott

Committee Member 3 School

Mathematics and Natural Sciences

Committee Member 4

Michael Vera

Committee Member 4 School

Mathematics and Natural Sciences

Abstract

The ability to detect radiation through identifying secondary effects it has on its surrounding medium would extend the range at which detections could be made and would be a valuable asset to many industries. The development of such a detection instrument requires an accurate prediction of these secondary effects. This research aims to improve on existing modeling techniques and help provide a method for predicting results for an affected medium in the presence of radioactive materials. A review of radioactivity and the interactions mechanisms for emitted particles as well as a brief history of the Monte Carlo Method and its application to radiation transport are provided. Many software packages have been previously developed for the purposes of radiation transport modeling efforts. Geant4 was selected, implemented, and evaluated as a candidate for the inclusion of molecular interaction mechanisms. It was determined that Geant4 requires further customization to accurately account for the prediction of very low energy secondary electrons, and these interaction calculations must still be handled separately. Additionally, it was determined that the distance traveled by low energy secondary electrons is small enough to be considered negligible relative to the path length of the primary. This allowed for a transition away from performing a transport calculation to a separate approach for predicting the effect on the medium. Subsequently, the calculations for the newly developed Averaged Loss Method and its implementation are described. When compared to results obtained through a separate Monte Carlo simulation, the Averaged Loss Method is found to be successful and potential avenues for the further improvement of this method are outlined as well.

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