WINKLER: An imaging high resolution gamma-ray spectrometer

The WINKLER high-resolution gamma-ray spectrometer was originally developed to fly on a high-altitude aircraft. Following the discovery of Supernova 1987A in the Large Magellanic Cloud arrangements were made to perform balloon-borne observations of this event. The instrument was quickly adapted to fit on a gondola furnished by NASA/MSFC in a collaborative effort and was flown in a series of three successful flights from Alice Springs, Australia. The second flight on October 29-31, 1987 resulted in the first high-resolution detection of the 847-keV line emission from the decay of /sup 56/Co and provided definitive confirmation of the explosive nucleosynthesis process. WlNKLER comprises an array of nine coaxial n-type germanium detectors which are housed in a common vacuum cryostat and surrounded by an NaI(Tl) scintillator shield that suppresses Compton interactions and gamma-ray background. Gamma-ray images are obtained with a rotational modulation collimator system attached to the spectrometer. Collimator holes in the upper section of the shield define the angular field of view of the instrument to 22 degrees full width at half maximum. The energy range of the spectrometer is 20 eV to 8 MeV, and the composite energy resolution from all detectors is 1.5 keV at 100 keV and about 2.5 keV at 1.33 MeV.<
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