Secondary particle identification using the relativistic rise in ionization

We report on the data analysis and techniques used to determine particle identification from the relativistic rise in ionization as detected by CRISIS, a 1 × 1 × 3 m³, 192 cell, ionization-sampling drift chamber containing an 80% argon/20% carbon dioxide gas mixture. For 100 GeV/c protons/antiprotons (pions) we obtain an ionization FWHM of 7.6% (7.9%), which compares well with the design value of 7.8%. The separation between the mean ionization values for the protons and pions was determined to be 7.9%. We also present the analysis of particle identification for secondary particles produced by interactions in the bubble chamber. A statistical method for correcting for the overlapping ionization curves from secondary protons/antiprotons and pions is discussed.