The performance of a position sensitive wire chamber in the presence of a magnetic field

We have built a position sensitive wire chamber and tested it with X-rays and cosmic ray muons. Using a fill gas of 62% CF4 and 38% CO2, we have achieved resolutions of 38 μm for 1 keV X-rays, 42 μm for normally incident cosmic ray muons in the absence of a magnetic field, and 46 μm for cosmic rays incident at the gas's Lorentz angle for a 0.8 T magnetic field. For throughgoing charged particles, the degradation in position resolution with angle away from the optimum incident angle has been found to be 11 μm/° (added in quadrature).