5/12/2008 Colloquium - Dan Chivers

Dan Chivers UC Berkeley

Event Info

Title:  Semiconductor Detectors for Compton Gamma Ray Imaging: Current Technology and Future Research Thrusts

Date: May 12, 2008
Location: 3105 Etcheverry Hall
Time: 4-5pm

Abstract

Compton gamma-ray imaging systems have been developed at LLNL for use in detecting weak radiological sources within a complex natural background. These systems utilize thick germanium and silicon strip detectors that have shown spatial resolution of interaction sites of order ~1mm. Modeling of signal shapes along with full signal decomposition has recently been shown to yield a spatial resolution of ~300 micron with the additional capability unfolding cross-induced signals from multiple interactions in close proximity. The result of this decomposition effort is not only an increase in detection sensitivity of weak radiological sources, but also a deeper understanding of how to model charge tracks as they drift and spread prior to collection. It is envisioned that these models will be utilized in the next phase of Compton imaging where we will seek to sense both the position of interactions along with the initial trajectory of the resulting high energy electron. Electron track Compton imaging promises to provide a marked increase in gamma imaging efficiency therefore having an impact on the detection challenges within homeland security applications.