Particle identification using cluster counting in a large drift chamber atnormal conditions

Results on particle identification obtained measuring the primary ionizatio n in a drift chamber operating in a mixture He 80%-CH4, 20% at normal condi tions are presented. The data, collected at CERN (PS T9 beam), indicate tha t the cluster-counting technique allows a substantial improvement with resp ect to the more traditional measurements. pi/K separation of similar or equ al to 3.6 sigma at 4 GeV was obtained over the entire volume of the chamber : 144 (3 x 3) cm(2) cells with an average tracks path length of 120 cm. (C) 1999 Elsevier Science B.V. All rights reserved.