Measurements of drift velocity in the ATLAS RPC gas mixture

We present here some results on measurements of electron drift velocity as a function of the electric field in a single gap, avalanche operated, small size (10 × 20 cm2) RPC filled with a ternary gas mixture (94.3 % C2H2F4, 5 % C4H10, 0.3 % SF6). A pulsed nitrogen laser is focused (∼ 20 μm spot size at the focus) inside the gas gap to generate primary ionization via double photon ionization process. Results are presented and discussed.