[en] An experimental study of the scintillation properties of Ar-Xe mixtures has been carried out with a gas proportional scintillation counter instrumented with a photomultiplier tube. Energy resolutions of 7.7, 7.8, 7.8, 8.3, 8.5, 9.1 and 11.5% were obtained for 5.9 keV X-rays respectively for the 100% Xe, 60%Ar-40%Xe, 80%Ar-20%Xe, 90%Ar-10%Xe, 95%Ar-5%Xe, 97%Ar-3%Xe and 99%Ar-1%Xe mixtures at 800 Torr. Thresholds for scintillation and ionization were also determined. The performance of Ar-Xe mixtures as detection media in large detection area applications has been studied for a 52 mm diameter photomultiplier and a 38 mm diameter radiation window. The curved grid technique was used to minimize spectra distortion due to solid angle effects.

[en] A recently used experimental technique for measuring the mobility of positive ions in their parent gases is applied to methane (CH₄ purity ≥99.995%), where ion reduced mobility values K₀ are deduced from the analysis of measured time-of-arrival spectra of the ions produced by a GEM. For CH₄ pressures in the range 3 to 10 Torr, two peaks could be observed when reduced applied fields E/N were varied from 10 to 60 Td, where E/N is the ratio of electric-field strength to gas-number density. The corresponding extrapolated zero-field mobility values in CH₄ were found to be K₀ = 2.58 cm² V⁻¹ s⁻¹ and K₀ = 2.42 cm² V⁻¹ s⁻¹, belonging likely to CH₅⁺ ions on the 1^st peak and to C₂H₅⁺ and C₃H₇⁺ ions, with similar mobility values and falling both under the 2^nd peak.

[en] We measured the reduced mobility of the nitrogen, N₄⁺, ion in N₂, under different pressures and reduced electric fields at 298 K using a new technique. Extrapolation to zero field yields a value of 2.37 cm²V⁻¹s⁻¹, which is in good agreement with other published data.

[en] In this paper we present the results for the ion mobility measurements made in gaseous mixtures of xenon (Xe) and nitrogen (N₂) for low reduced electric fields (in the 15 Td to 30 Td range), at room temperature. The choice of reduced electric fields was guided by typical gaseous detector's demands. In the 0–100% range of Xe concentrations in the mixture, only one peak was observed which was attributed to Xe₂⁺; in fact its mobility was found to follow Blanc's law. A typical time-of-arrival spectrum for 90% Xe and 10% N₂ is shown. The reduced mobilities, obtained from the peaks, are calculated and presented in this paper

[en] We describe a simple experiment intended for didactic laboratory vacuum classes of undergraduate courses, using a residual gas analyser (RGA): the determination of the natural abundance of the different isotopes of a given element in a gas sample. In addition to the understanding of the RGA operation and handling principles, the experiment allows the students to perform direct quantitative measurements of isotopic abundances and compare with the results tabulated in the literature. As an example, sets of measurements are presented for xenon and neon using a quadrupole mass spectrometer. The experimental results obtained are in good agreement with the values presented in the literature

[en] In this paper we present the results of the ion mobility measurements made in gaseous mixtures of argon (Ar) and methane (CH₄) for pressures ranging from 5 to 8 Torr and for low reduced electric fields (in the 17 Td to 43 Td range), at room temperature. The time of arrival spectra of the several mixture ratios studied revealed that the relative abundance of the ions formed depend on the mixture ratios. For CH₄ concentrations in the 2.5–10% range three well defined peaks were observed which were attributed to single-carbon ions (CH₅⁺), 2-carbon ions (C₂H₄⁺ and C₂H₅⁺), and 3-carbon ions (C₃H₄⁺, C₃H₅⁺, C₃H₆⁺ and C₃H₇⁺). The time of arrival spectra for CH₄ concentrations of 2.5% (P-2.5), 5% (P-5), 10% (P-10) and the reduced mobilities of the ions obtained from the peaks observed are presented in this paper. The ion mobility study was performed for typical reduced electric fields used in gaseous detectors (E/N > 15 Td)

[en] In this paper we present the experimental results for the mobility of ions in argon-carbon dioxide gaseous mixtures (Ar-CO₂) for pressures ranging from 6 to 10 Torr and for reduced electric fields in the 10 Td to 25 Td range, at room temperature.The time-of-arrival spectra of the several mixture ratios studied revealed that the relative abundance of the ions and their mobilities depend on the mixture ratio. For Ar concentrations below 80% only one peak was observed in the spectra which was attributed to CO₂⁺, while for Ar concentrations above 80% a second peak appears at the left side of the main peak, which may be due to impurities, probably H₂O⁺. In this work, the time-of-arrival spectra from which reduced mobilities were obtained for Ar concentrations of 20% (K₀ = 1.141±0.004 cm²V⁻¹s⁻¹), 50% (K₀ = 1.385±0.009 cm²V⁻¹s⁻¹), 85% (K₀ = 1.690±0.022 cm²V⁻¹s⁻¹) and 95% (K₀ = 1.954±0.043 cm²V⁻¹s⁻¹) are displayed as well as other reduced mobilities values obtained similarly. The ion mobility study was performed at reduced electric field values typically used in gaseous detectors

[en] A gamma-ray telescope mission concept [gamma ray imager (GRI)] based on Laue focusing techniques has been proposed in reply to the European Space Agency call for mission ideas within the framework of the next decade planning (Cosmic Vision 2015-2025). In order to optimize the design of a focal plane for this satellite mission, a CdZnTe detector prototype has been tested at the European Synchrotron Radiation Facility under an ∼100% polarized gamma-ray beam. The spectroscopic, imaging, and timing performances were studied and in particular its potential as a polarimeter was evaluated. Polarization has been recognized as being a very important observational parameter in high energy astrophysics (>100 keV) and therefore this capability has been specifically included as part of the GRI mission proposal. The prototype detector tested was a 5 mm thick CdZnTe array with an 11x11 active pixel matrix (pixel area of 2.5x2.5 mm²). The detector was irradiated by a monochromatic linearly polarized beam with a spot diameter of about 0.5 mm over the energy range between 150 and 750 keV. Polarimetric Q factors of 0.35 and double event relative detection efficiency of 20% were obtained. Further measurements were performed with a copper Laue monochromator crystal placed between the beam and the detector prototype. In this configuration we have demonstrated that a polarized beam does not change its polarization level and direction after undergoing a small angle (<1 deg.) Laue diffraction inside a crystal