par Sixel, P.;Spyropoulou-Stassinaki, Martha;Vassiliadis, G.;Johnson, Denis;Theocharopoulos, P.;Baruzzi, V.;Goldschmidt-Clermont, Yves ;Grant, A.;Lehraus, I;Matthewson, R.;Ross, Robert;Tejessy, W;Wright, P.R.S. P.R.S.;Zoll, J.;Carosio, R.;Crijns, F.;Stergiou, A.;Gerdyukov, L.N.;Nikolaenko, V.N.;Petrovikh, Y.L.;Milstene, Caroline;Oren, Yona;Kröner, F.
Référence Nuclear Instruments and Methods in Physics Research, 207, 3, page (339-356)
Publication Publié, 1983-04
Référence Nuclear Instruments and Methods in Physics Research, 207, 3, page (339-356)
Publication Publié, 1983-04
Article révisé par les pairs
Résumé : | Fast secondary particles from interactions of K+ at 70 GeV/c and K- at 110 GeV/c in the BEBC hydrogen bubble chamber are identified by use of the relativistic rise of ionization in argon. The ionization is measured in a large multicell ionization counter system, the External Particle Identifier (EPI). The operation of this hybrid system, the calibration and the procedures of off-line analysis leading to particle identification are described. For a sample of 9283 secondary particles collected in the K+ p experiment, we present the measurements of ionization, and the determination of acceptance and identification efficiencies. The momentum-dependent populations of pions, kaons and protons have been obtained. Track by track identification procedures yielding samples of pions and kaons with a contamination {less-than or approximate} 12% are discussed. A study of the resolution of the EPI in these experimental conditions shows average values in a range of 7.6% to 11% depending on the number of ionization samples remaining after removal of background. These values extrapolate to a value consistent with the 6.6% fwhm measured over the whole device for single particles during calibration with a 50 GeV/c π- beam. © 1983. |