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1 October 1991 Imager for gamma-ray astronomy: balloon prototype
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A novel low energy astronomical gamma-ray detector is being developed for future satellite missions. Recent advances in the technology of photodiodes and small, low noise amplifier circuits have meant that more compact detectors can be assembled in a complex array in order to give a 3-D position reconstruction capability. In a mask-detector telescope this capability is potentially very useful since it allows the reconstruction of the path of the incident gamma rays making it valuable both for imaging and background rejection. A small prototype of a 3-D detector has been realized for test in a balloon mission. The detector is based on a 12 X 8 array of position sensitive CsI(T1) bars, typically 15 cm long with 1.3 X 1.3 cm cross section, viewed at each end by photodiodes. The detector includes four 1.3 X 1.3 X 2.5 cm CsI(T1) scintillators located above the main array in order to evaluate the low energy response of the imager. The detector constitutes an active block of 2400 cm3 of scintillator that can operate in the 0.2 - 10 MeV energy range. The energy resolution is 13% at 662 keV and the positional resolution is of the order of 1.5 cm in each dimension. An active shield of CSI(T1) and plastic scintillators surrounds the bar detector. The overall experiment is briefly described in general and preliminary results of laboratory tests are presented.
© (1991) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

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