WINKLER

This paper reports on 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 important 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 29-31 October 1987, resulted in the first high resolution detection of the 847 keV line emission from the decay of 56Co and provided definitive confirmation of the explosive nucleosynthesis process. WINKLER comprises an array of nine coaxial n-type germanium detectors which are housed in a common vacuum cryostat and surrounded by a NaI(T1) scintillator shield that suppress 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 FWHM. The Ge detectors are cooled to about 75K with a solid nitrogen cooler having a 5 day lifetime at float altitude