Detector pulse shape analysis for X-ray scatter based baggage inspection systems

Segmented HPGe-detectors are key components in baggage inspection systems based on elastic X-ray scattering. Their high price represents a major obstacle on the way to more cost effective systems. Here we describe our first steps towards replacing the necessary (radial) crystal segmentation by time resolved analysis of the charge collection pulses obtained from a "true-coaxial" HPGe-detector. We are demonstrating the pulse shape differences we observed in our measurements for different absorption radii using Am-241 and Co-57 radiation and compare the shapes with our expectation derived from a simple model of charge collection within the crystal taken from literature. From these results it appears feasible to achieve a radial resolution in the region of 5-7 mm by pulse shape analysis using appropriate pulse processing electronics and signal processing software.