Detecting the presence of possible illicit radioactive materials in large areas is challenging because of changing background radiation, shielding effects and short collection time, especially when the radioactive materials are moving. The concept of mobile sensor networks is put forward to solve this problem. In this thesis, a small mobile sensor network is established using commercially available radiation detectors and cell phones. A spectrum decomposition and reconstruction method based on Principal Component Analysis (PCA) is proposed to work with mobile sensor networks. Two experiments are designed to test this method's performance on real-world data. The PCA-based method's performance is analyzed using receiver operating characteristic, or ROC curves. Further study finds that although the PCA-based method doesn't work well on current mobile sensor networks, its performance can be improved by increasing the radiation spectral quality
