The spectrometer SPI
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The spectrometer, SPI

January 5, 2013
The Spectrometer on Integral (SPI) will allow gamma-ray energies to be measured with exceptional accuracy. It will be much more sensitive to fainter radiation than any previous high-accuracy gamma-ray instrument. SPI will be used to analyse gamma-ray sources over an energy range between 20 keV and 8 MeV, using an array of 19 hexagonal high-purity germanium detectors, cooled to -183 degrees Celsius (90 Kelvin). To reduce interference, the detector is shielded by bismuth germanate oxide crystals, extending around the bottom and side of the detector almost completely up to the coded mask. As a consequence of its construction, SPI is extremely heavy, with a mass of 1300 kilograms. The principal investigating institutions for SPI are CESR Toulouse, France and MPE Garching, Germany. Copyright: ESA 2002

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