Recently the impact of gamma-ray imaging for nuclear security applications has been recognized, where the goal is to provide improved capabilities to detect, localize, and characterize nuclear materials. We report on our evaluation of the possible gains in detection sensitivity with an electron tracking-based Compton imaging system. The goal of this research is the systematic evaluation of electron tracking-based Compton imaging and its comparison with conventional, non-electron tracking based Compton imaging instruments. Our current approach is based on high-resolution Si-based charge coupled devices (CCDs) providing excellent position and energy resolution.
We are developing data processing schemes that are able to fully exploit the potential gains of electron-tracking based Compton imaging. The focus of this work is the gamma-ray event reconstruction starting from the observation and interpretation of the electron track all the way to the reconstructed gamma ray and its incident direction. We have developed and implemented a range of algorithms and Monte-Carlo simulation tools that allow us not only to understand observable features of the specific detectors we are using but also to determine the fundamental limits in this approach and to predict performances of larger-scale systems. We are currently implementing gamma-ray reconstruction schemes, which allow us to compare a variety of electron-tracking and non-electron-tracking based Compton imaging implementations. For these quantitative comparisons we are employing efficiency and resolution metrics as figure of merit.