A facility for the measurement of electron transport parameters in a gas mixture

A facility for studying electron transport parameters in a given gas mixtur e is illustrated. A controlled ionization is induced by means of multiple-p hoton processes by focussing a short (similar to 1 ns) pulsed nitrogen lase r in the gas gap. The test gas volume, where a suitable E-field is applied, is installed on a micrometric motion system which allows to accurately sca n the volume (resolution similar to 3 mum) with a beam focus waist of the o rder of 10 mum. Such a facility has been used for measurements of the gas p arameters of the He drift chamber of KLOE experiment at DA phi NE and for p reliminary measurements of gain and attachment coefficients in the binary m ixtures (C2H2F4 + 3%, 10% isoC(4)H(10)) planned for the ATLAS and CMS RPC s ystems. An upgraded version of the set-up, which allows also for O-2 and H2 O vapour controlled contamination, is currently being used for measurements on ternary mixtures (C2H2F4 + isoC(4)H(10) + SF6). (C) 2001 Elsevier Scien ce B.V. All rights reserved.