Digital gamma-ray tracking algorithms in segmented germanium detectors

Abstract

A gamma-ray tracking algorithm has been implemented and tested, using simulated data, for gamma rays with energies between 0.1 and 2 MeV, and its performance evaluated for a 90-mm-long, 60-mm-diameter, cylindrical, 36 (6 6) segment detector. The performance of the algorithm in two areas was determined: Compton suppression and Doppler shift correction. It was found that for gamma rays of energies around 1 MeV, a ratio of photopeak counts to total counts of 2 : 3 could be obtained using the tracking algorithm, with only a 2% reduction in detection efficiency, compared to the untracked data. Approximately 80% of first interaction points could be correctly identified, enabling a good Doppler shift correction. A detector of the type simulated has recently been delivered, together with a compactPCI digital data acquisition system comprising 36 12-bit, 40-MHz flash ADCs, and 6 200-MHz DSPs. Some initial data has been recorded using this system, and the performance of the tracking algorithm on this real data is comparable to its performance on simulated data.

A fast VLSI preamplifier for segmented HPGe γ-ray detectors

“…The availability of highly segmented HPGe detectors, makes it possible to measure the spatial coordinates of the points where the impinging gamma photon interacts inside the detector crystal, and to perform the so-called gamma-ray tracking [1][2][3]. Segmented HPGe detectors will be employed worldwide in the near future for next-generation nuclearphysics experiments with exotic ion beams.…”