Uniformity of the 1996 Barrel Module 0 response to muons and pions: Test Beam data and MC simulation

The uniformity of the Barrel Module 0 light yield was studied using three sources of information: 180GeV muons impinging the module 0 at 90 degrees, the Cesium source and the light yield calculated using a parametrization for tiles and fibres. The cesium source and muons give an average tile-to-tile fluctuation of ~+-8% while the maximum fluctuation on the calculated light yield is ~+-5%. The number of photoelectrons per tile size was calculated using the data from the detailed muons scan and a mean number of ~27 photoelectrons per GeV was obtained for the module 0. The uniformity of the response of the module 0 to 180GeV muons and 100GeV pions was studied as a function of the impact point z and eta. The signal response shows a modulation for eta values close to zero which is a consequence of the structural periodicity of the Module 0. The maximum fluctuation on the signal is ~+-(50-60)% of the energy lost by muons in the module 0 for eta=0. The amplitude of the modulation is smaller for pions because the dimensions of the showers makes them less sensitive to the local structure.