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Imaging Performance of the Si/Ge Hybrid Compton Imager

Description: The point spread function (PSF) of a fully-instrumented silicon/germanium Compton telescope has been measured as a function of energy and angle. Overall, the resolution ranged from 3{sup o} to 4{sup o} FWHM over most of the energy range and field of view. The various contributions to the resolution have been quantified. These contributions include the energy uncertainty and position uncertainty of the detector; source energy; Doppler broadening; and the 1/r broadening characteristic of Compton back-projection. Furthermore, a distortion of the PSF is observed for sources imaged off-axis from the detector. These contributions are discussed and compared to theory and simulations.
Date: November 10, 2005
Creator: Burks, M; Chivers, D; Cork, C; Cunningham, M; Fabris, L; Gunter, D et al.
Partner: UNT Libraries Government Documents Department

First-Generation Hybrid Compact Compton Imager

Description: At Lawrence Livermore National Laboratory, we are pursuing the development of a gamma-ray imaging system using the Compton effect. We have built our first generation hybrid Compton imaging system, and we have conducted initial calibration and image measurements using this system. In this paper, we present the details of the hybrid Compton imaging system and initial calibration and image measurements.
Date: November 7, 2005
Creator: Cunningham, M; Burks, M; Chivers, D; Cork, C; Fabris, L; Gunter, D et al.
Partner: UNT Libraries Government Documents Department

Methods for increasing the efficiency of Compton imagers

Description: A Compton scatter camera based on position sensitive, planar Ge and Si(Li) detectors with segmented electrodes is being developed at LLNL. This paper presents various methods that were developed to increase the position resolution of the detectors, the granularity and capability to reconstruct the scattering sequence of the gamma-ray within the detectors. All these methods help to increase the efficiency of the imager, by accepting more photons in the final image. The initial extent and diffusion of charge-carrier clouds inside the semiconductor detectors are found to affect profoundly the fraction of interactions that deposit charge in multiple adjacent electrodes. An accurate identification of these charge-shared interactions is a key factor in correctly reconstructing the position of interactions in the detector.
Date: November 15, 2005
Creator: Mihailescu, L; Vetter, K; Burks, M; Chivers, D; Cunningham, M; Gunter, D et al.
Partner: UNT Libraries Government Documents Department