The HADES tracking system consists of four drift chambers (I-IV), two before and two behind the field area of the superconducting toroid. Each drift chamber is composed of six trapezoidal modules and has the form of a frustrum. A module covers 60 degrees of azimuthal angle and 4 modules of the detectors I to IV each form a sector. Module sizes range from 88 cm x 80 cm to 280 cm x 230 cm (height times larger baseline).

A chamber module is composed out of six drift cell layers. The cell sizes vary from 5x5 mm2 to 14x10 mm2 from detector I to IV to achieve a constant granularity. The cells are formed by interspersed sense and field wires and cathode wire planes. The total number of drift cells is 27.000.

The chambers are equipped with dedicated preamplifier/shaper/discriminator boards inserted into motherboards which itself contain the digitisers (TDC). These daughter/motherboard components are mounted onto the detector frames. The read-out concept foresees data concentration in three levels.

Participating Institutions

Gesellschaft für Schwerionenforschung Darmstadt (GSI)
Plane I construction, readout electronics, chamber installation
Forschungszentrum Rossendorf (FZR)
Plane III construction
Joint Institute of Nuclear Research (JINR)
Plane II construction, readout electronics
Johann Wolfgang Goethe-Universität Frankfurt
Plane I construction, readout electronics, chamber installation
Institut de Physique Nucleaire d'Orsay
Plane IV construction

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