Particle identification with the JETSET straw chambers

Feasibility studies on particle identification were performed for the barrel drift-tube (“straw”) chamber of the JETSET (PS202) experiment at CERN-LEAR. The energy loss of traversing particles was investigated using elastic p̄p scattering (0.3≲β≲0.7) and the reaction pp → π+π− (β ≈ 0.995). The resulting distributions could be reproduced well by a Landau function, convoluted with a Gaussian in the low β case. A weighted mean was calculated out of the 5–17 single-straw samplings of a track as an estimate for its mean differential energy loss. A resolution of about 10% was obtained. Using the Bethe-Bloch equation without corrections, a resolution σβ ≈ 0.03 was achieved for tracks from elastic scattering. The long-term behaviour was studied, yielding information about aging effects and the dependence of the energy loss on counting-gas parameters.