ARI-MA: Electron Tracking for Advanced Gamma-Ray Imaging Applications in Homeland Security

University Of California-Berkeley, Berkeley CA

Investigators

Abstract

The goal of this project is to enhance the recently demonstrated concept of electron-tracking based Compton imaging of gamma radiation. This concept promises to increase the detection, localization, and characterization capabilities for nuclear security but also in other areas such as biomedical imaging or astrophysics. Our approach is based on high-resolution Si-based charge-coupled device (CCD) sensors which provides sufficient resolution to determine the initial direction of the electron that was scattered by means of the Compton scattering process. This enables the reconstruction of incident gamma rays on event-by-event basis without using a sensitivity-limiting collimator. The combination of Si and a pixel size of 10 um enables both sufficient position resolution to determine the incident direction and efficiency to induce the Compton scattering process. This project specifically aims at systematically evaluate and enhance the current implementation in terms of hardware and software. Preliminary algorithms to track the electron and to perform image reconstruction have been developed which can be improved by taking into account more details of the features that can be observed and by correlating the electron and gamma-ray information. The slow frame rate of the CCD approach is currently limiting the event-to-event reconstruction. We will implement the strip readout of the CCD to enable the event-to-event reconstruction of the electron track and the associated gamma ray and demonstrate electron-tracking-based Compton imaging in real time. The goal of this project is the demonstration of a new concept in radiation detection that enables potentially significant increased capabilities in the detection, localization, and characterization of nuclear materials. Recent and ongoing developments of very-high-resolution Si sensors can be used to measure details of interaction processes that can be used to gain more information to reconstruct gamma radiation. Applications can be envisioned in homeland security, nuclear non-proliferation and international safeguards, biomedical imaging as well as astrophysics and nuclear physics. The project will provide the excellent training of young scientists.