Light-polarization measurements have been performed after polarized-electron impact excitation of the xenon resonance levels. Both electron-photon coincidence experiments as well as measurements of the integrated Stokes parameters have been carried out with a vacuum-ultraviolet analyser ofthe reflection type. A complete set of integrated Stokes parameters is given, which partly depend on the electron polarization and allow one to draw conclusions on spin eKects involved in the scattering process. At a scattering energy or 25 eV and angles between IO" and 20" a spin up-down asymmetry was measured using the coincidence technique. A comparison of our experimental data with a DWBA calculation shows good agreement.

A new reference calorimeter has been developed under a European research project and set-up by Physikalisch-Technische Bundesanstalt (PTB) in Germany. The objective of the project is to measure the superior calorific value (SCV) of methane and other pure gases with a measurement uncertainty of less than 0.05 %. This paper presents the measurement results obtained for methane. Nine repeatability measurements were made. The molar SCV obtained when the measurements were averaged is 890.578 kJ·mol −1 . This value agrees very accurately with the value of 890.63 kJ·mol −1 specified by ISO 6976 [Natural Gas-Calculation of Calorific Values, Density, Relative Density and Wobbe Index from Composition. International Standard ISO 6976, corrected and reprinted 1996-02-01]. Twice the standard deviation determined for the measurements is 0.023 % and is thus clearly lower than in previous 123 666 Int J Thermophys (2010) 31:665-679experiments. Two independent uncertainty analyses confirm that the envisaged total uncertainty of 0.05 % is achieved (95 % confidence level).

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