The 4 pi cylindrical detector SPC/XDC for X-ray and charged particles detection in antiproton annihilations in the OBELIX experiment at LEAR

The central detector of the OBELIX experiment has been in operation at the Low-Energy Antiproton ring (LEAR) during the 1990 runs with antiprotons at rest. The detector-called the Spiral Projection Chamber (SPC) or the X-ray Drift Chamber (XDC) depending on whether its use for charged particles or for X-ray is emphasized-surrounds a cylindrical gas target at NTP, from which it is separated by a very thin Mylar foil, and is positioned along the axis of the open axial field magnet in the center of the Obelix experiment. The characteristics of the detector are described, and its initial performance is discussed.<
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