Three-Dimensional Position-Sensitive Geranium Detectors

A critical component of the DOE decontamination and decommissioning effort is the characterization of radioactively contaminated equipment and structures. Gamma-ray spectroscopy and imaging with germanium (Ge) based detectors are powerful techniques that allow for the quick and accurate in-situ identification, spatial mapping, and quantification of radioactive contaminants. However, the image resolution obtained with a Ge detector can be limited by the accuracy to which the gamma-ray interaction events are spatially detected within the detector itself. Our primary objective is to develop the technologies necessary to produce Ge gamma-ray detectors with enhanced accuracy in locating gamma-ray interaction events thereby resulting in improved image resolution. Our approach is to locate the gamma ray interaction events within the detector in all three dimensions rather than just two. Additionally, we will base the detectors on known and tested LBNL fabrication technologies and utilize the simplest possible detector geometries and signal-readout electrode structures in order to reduce the system complexity and difficulties in fabrication. The technologies developed as a result of this research will form the basis for the design and construction of future high-performance gamma-ray imaging systems. These instruments will greatly facilitate DOE's radioactive materials characterization process