Attenuation length measurements in narrow drift channels

Abstract The attenuation length of electrons drifting under the action of a uniform electric field E d in a long (1 m) and narrow (8×100 mm 2 ) channel has been measured. The drift volume was filled with Ar+20% CH 4 at atmospheric pressure. The measurement has been done without and with a 1.2 T solenoidal magnetic field whose orientation, relative to the E d field, could be adjusted. Attenuation lengths larger than 4 m were measured.