Performance of a large magnet spark chamber

Abstract The description of a 60 × 67 × 160 cm 3 spark chamber in a 10.5 kG magnetic field and a report on its performance are given. This instrument was used at the CERN Proton Synchrotron for the detection of the neutral (and non-π 0 ) reaction products of π − , K − and p on hydrogen. The sources of the systematic deviations in spark position have been investigated and corrections have been devised to compensate for them. The residual random errors are: 1. 1. the rms deviation of individual sparks from the fitted trajectory σ y = 0.18 mm in space. 2. 2. the rms measurement error σ y meas = 0.09 mm in space. The MDM of the instrument is 1000 GeV/ c and the rms error in the mass of K 1 0 mesons of 7 GeV/ c momentum is Δm = 7.3 MeV/ c 2 .