R.D.Settles7,

Preliminary results of the spatial resolution of a GEM TPC with Ar-CF4 (3%)-iC4H10 gas mixtures are reported. 1 ILC TPC and Ar-CF4 gas mixtures The Time Projection Chamber (TPC) with the Micro-Pattern Gas Detectors (MPGD) is one of the candidates of the main tracker at the International Linear Collider (ILC). Three MPGD TPCs described in the ILC Reference Design Report [1] have the dimension of 2.8-4 m in diameter and 3-4.6 m in length. They are to provide 200 space points along each particle track with the Rφ spatial resolution of 100 μm or better. The momentum resolution of δ(1/pt)≤0.5 x 10-4 (GeV/c)-1 is envisaged in the magnetic filed of 3-4 T. Fig.1 The Rφ spatial resolution of GEM TPC calculated by the analytic formula for Ar(97%)-CF4 (3%) gas mixture in the magnetic field up to 4T [3]. The spatial resolutions of MPGD TPCs hav