Time Projection Chamber at TRIUMF

The Time Projection Chamber at TRIUMF is being used to search for muon-electron conversion. The best spatial resolution in the TPC, sigma approx. = 200 μm, occurs at the minimum drift length and for an optimum track-to-anode crossing angle determined by the magnetic field. The observed resolution is dependent on the diffusion of the drifting electrons, the track-to-anode crossing angle, vector E X vector B effects near the anode wire and the discrete nature of the ionization process. Distortion due to positive ions leaking back into the drift volume from the anode wire region have been nearly eliminated by the use of a pulsed dual grid system