The dependence of pulse height on anode diameter and gas composition in limited steamer tubes

The authors present results of a study of charge spectra using plastic streamer tubes as a function of anode diameters and for an extensive selection of three component gas mixtures of argon, isobutane, and carbon dioxide. Chambers instrumented with longitudinal strip and pad readout were constructed with plastic steamer tubes with anode wires of one of six different diameters: 25, 50, 75, 100, 150, 200 μm. The six chambers were simultaneously triggered by cosmic-ray muons, and the charge distributions were recorded for various voltages and gas mixtures. An unexpected scaling law may be at work during the transition to streamer mode