Test of a small prototype of the KLOE drift chamber in magnetic field

Abstract We report on a beam test of a small prototype of the KLOE drift chamber in magnetic field. The chamber was operated with a 90% He–10% iC 4 H 10 gas mixture. Drift space–time relations were studied. The average spatial resolution is about 110 μm in the absence of magnetic field and 120 μm in a 0.6 T magnetic field. Measurements of the primary ionization and drift velocity are reported. The measurement of d E /d x in a He-based gas mixture is also discussed.