A SOLID-STATE SPECTROMETER FOR COOLED BEAMS WITH HIGH ACCEPTANCE AND RESOLUTION IN SPACE AND ENERGY

The GEM detector, a hybrid system consisting of the Germanium Wall and the magnetic spectrometer BIG KARL, was developed to investigate meso n production and meson-nucleus interaction with cooled external proton beams from the COSY accelerator at Julich. The Germanium Wall is a st ack of up to four annular position-sensitive semiconductor detectors m ade from high-purity germanium. Its special structure allows experimen ts with high counting rates. Design features and results from first te st runs with the uncooled COSY beam are presented.