The drift chamber array at the external target facility in HIRFL-CSR

A drift chamber array at the External Target Facility in HIRFL-CSR has been constructed for three-dimensional particle tracking in high-energy radioactive ion beam experiments. The design, readout, track reconstruction program and calibration procedures for the detector are described. The drift chamber array was tested in a 311 AMeV Ar-40 beam experiment. The detector performance based on the measurements of the beam test is presented. A spatial resolution of 230 mu m is achieved.