Physics and Instrumentation of Gamma Ray Imagers Based on 3-D Position Sensitive Germanium Strip Detector

Morgan Burks
Lawrence Berkeley National Laboratory
July 2, 2002

Abstract:
Germanium-based gamma ray detectors give the best energy resolution of any comparable technology and have been used for decades for spectroscopy. Technological advances in the last couple of years have made it practical to turn Germanium-based spectrometers into full imaging systems. Applications include astronomical imaging as well as nuclear non-proliferation and site remediation. These detectors, fabricated with orthogonal strips on either side, provide 3-D position sensitivity, timing and coincidence, interpolation information as well as excellent energy resolution for one or even multiple simultaneous photon interactions. However, extracting all this information efficiently requires an in-depth understanding of the signal generation process in germanium strip detectors. We have spent considerable time studying these detectors and are constructing an 80 channel imager which takes advantage of the knowledge gained. I will be describing this system and showing images and other results obtained. I will also discuss how we are using its novel features to improve the detector efficiency and image quality. Finally, I will be discussing some of the advances we are working on for future generation imagers.