A RADIAL PROJECTION DRIFT CHAMBER USING A CO2-IC4H10 GAS-MIXTURE

A cylindrical drift chamber with a radial drift field has been constructed for the SINDRUM II spectrometer. The chamber operates with a gas mixture of 70% CO2 and 30% iC4H10, and is used to project elements of particle tracks onto a single layer of anode wires close to the outer wall. The radial projection geometry allows a three-dimensional reconstruction of the trajectory by measuring the signals induced on cathode strips which cover the outer wall. The chamber has a spatial resolution of sigma = 150 mum in r - phi and of 3.8 mm in z. We discuss the design and construction of this chamber, its performance and calibration with cosmic rays, and its use in a mu --> e conversion experiment.