[en] The stability of operation and the detection efficiency of drift chambers running in streamer mode are substantially improved when adding a few percent of organic vapour to gas mixtures composed of Ar, CO₂ and iC₄H₁₀. (orig.)

No abstract available

[en] Gaseous avalanche counters with mixtures containing the vapour of triethylamine, are coupled to an optical readout system. Different configurations are studied in order to visualize ionization tracks produced by high-energy particles or images caused by vacuum ultraviolet light. This instrument has potential applications in the study of rare or complex events - such as the search for double-beta and proton decay - or in Cherenkov ring imaging. (orig.)

[en] Successful operation of a drift chamber with 10 cm drift in the limited streamer mode is demonstrated. Good results were obtained with a 50-50 argon-isobutane gas mixture. A preliminary search for alternative gas mixtures avoiding the hydrocarbon quencher component is described. (orig.)

[en] This report presents the performance of 4.35 m long delay lines used for position sensing along the anodes of drift chambers operated in the limited-streamer mode. Using only the time difference between the signals at the two ends of the delay line, a spatial resolution ranging from 1.5 to 2.5 mm is obtained, equivalent to 0.06% of the 4.35 m length of the line. The linearity of the time-to-distance relation is also studied. (orig.)

[en] This report presents the performance of drift chambers operated in the limited streamer mode with 9.4 cm maximum drift distance and position sensing along the 4.35 m long anode wire through delay line timing. Using only three timing channels a position resolution of 1 . 3 mm² is obtained over a detector surface of 19 . 435 cm². In this contribution, the emphasis is mainly put on the performance of the delay line and on the drift behaviour in streamer mode using safe gas mixtures. (orig.)

[en] The layout and construction of the muon drift chambers equipping the end caps of the DELPHI detector are described. The performance of this forward muon detection system, determined from cosmic ray tests and data collected during the first year of LEP operation, is presented. (orig.)

[en] Recent measurements realized with Microstrip Gas Chambers (MSGC) manufactured on glass substrata in a range of bulk resistivity are presented. Chambers made on electronically conductive supports with resistivity of 10⁹ Ω cm and gold strips show a stable behaviour during long term irradiation up to an accumulated charge of 130 mC/cm of strip when operated in an argon-dimethylether (DME) mixture. Similar measurements realised with argon-methane show instead a fast degradation of gain already at collected charge of around 5 mC/cm. Further investigation of MSGC performance with different Ar-DME compositions show that the larger stable gain can be achieved with a 50-50 mixture. We present also results of beam runs performed with MSGC manufactured on Hoya SL glass with an anode to cathode distance of 200 μm and a 2 mm gas layer. The dependence of efficiency and spatial resolution on the incidence angle of track was measured with argon-DME and xenon-DME gas mixtures; for minimum ionizing particles perpendicular to the chambers (0 ) the spatial resolution for Xe gas mixture is 65 μm rms and the efficiency 98%. For incidence angles up to 10 a small degradation of both parameters was observed. ((orig.))

[en] A small series production of detector modules made of MicroStrip Gas Counters (MSGC) and a Gas Electron Multiplier (GEM) foil has been exposed to a high-intensity hadron beam. We report about the reproductibility and stability of the detector responses and about the occurrence and consequences of discharges in the detector. The interdependence of the four voltage differences used in the detector has been studied by simulation and with X-ray measurements. Rate dependence of the signal amplitude is observed. The behaviour of the MSGC+GEM is compared to that of a state-of-the-art MSGC. Influence of various parameters on the detector response is investigated

[en] A system of detector modules consisting of a large size Gas Electron Multiplier (GEM), coupled to Micro Strip Gas Counters (MSGC), has been exposed to a pion beam at the Paul Scherrer Institute Cyclotron facility. As part of a CMS tracker milestone, the aim of this test was to investigate the robustness of such detectors when exposed to experimental conditions close to what is expected at the Large Hadron Collider (LHC) of CERN. Eighteen detector modules have been operated at voltage settings corresponding to 98% detection efficiency for Minimum Ionizing Particles during a period of 5 weeks. Sparking rates and strip losses have been monitored throughout the exposure. An operation margin of at least a factor of three with respect to the required gas gain has been demonstrated