Beam test results of the prototype of the multi wire drift chamber for the CSR external-target experiment

The half-size prototype of the multi wire drift chamber (MWDC) for the cooling storage ring (CSR) external-target experiment (CEE) was assembled and tested in 350 MeV/u Kr+Fe reactions on the heavy ion research facility in Lanzhou (HIRFL). The prototype consists of 6 sense layers, where the sense wires are stretched in three directions X, U and V, meeting 0^∘, 30^∘ and -30^∘ with respect to the vertical axis, respectively. The sensitive area of the prototype is 76 cm × 76 cm. The amplified and shaped signals from the anode wires are digitized in a serial capacity array. Being operated with 1500 V high voltage on the anode wires, the efficiency for each layer is beyond 95%. The tracking residual is about 301 ± 2 μ m. The performance meets the requirements of CEE.