862 research outputs found

    Gain, Rate and Position Resolution Limits of Micropattern Gaseous Detectors

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    In this study we report the results of a systematic study of the gain, rate and the position resolution limits of various micropattern gaseous detectors. It was found that at low rates (<1 Hz/mm^2) each detector has it own gain limit, which depends on the size and design features, as well as on gas composition and pressure. However, in all cases the maximum achievable gain is less than or equal to the classical Raether limit. It also was found that for all detectors tested the maximum achievable gain drops sharply with the counting rate. The position resolution of micropattern detectors for detection of X-rays (6 to 35 kV) was also studied, being demonstrated that with solid converters one could reach a position resolution better than 30 micrometers at 1 atm in a simple counting mode.Comment: 10 pages, 3 figures, Presented at the PSD99-5th International Conference on Position-Sensitive Detectors, 13-17 th September 1999, University College, Londo

    Resistive plate chambers for time-of-flight measurements

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    The applications of Resistive Plate Chambers (RPCs) have recently been extended by the development of counters with time resolution below 100 ps sigma for minimum ionising particles. Applications to HEP experiments have already taken place and many further applications are under study. In this work we address the operating principles of such counters along with some present challenges, with emphasis on counter aging.Comment: Presented at "PSD6 - 6th International Conference on Position Sensitive Detectors", 9-13 September 2002, Leicester, UK. Submitted to Nuclear Instruments and Methods

    High Resolution RPC's for Large TOF Systems

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    Here we report on a particular type of RPC that presents up to 99% efficiency for minimum ionizing particles and a very sharp time resolution, below 50 ps sigma in the most optimized conditions. Our 9 cm2 cells, made with glass and metal electrodes that form accurately spaced gaps of a few hundred micrometers, are operated at atmospheric pressure in non-flammable gases and can be economically produced in large quantities, opening perspectives for the construction of large area time of flight systems.Comment: 10 pages, 8 figure

    High-resolution TOF with RPCs

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    In this work we describe some recent results concerning the application of Resistive Plate Chambers operated in avalanche mode at atmospheric pressure for high-resolution time-of-flight measurements. A combination of multiple, mechanically accurate, thin gas gaps and state-of-the-art electronics yielded an overall (detector plus electronics) timing accuracy better than 50 ps sigma with a detection efficiency up to 99% for MIPs. Single gap chambers were also tested in order to clarify experimentally several aspects of the mode of operation of these detectors. These results open perspectives of affordable and reliable high granularity large area TOF detectors, with an efficiency and time resolution comparable to the existing scintillator-based TOF technology but with a significantly, up to an order of magnitude, lower price per channel.Comment: 12 pages, 6 figures. (presented at the PSD99-5th International Conference on Position-Sensitive Detectors, 13-17 th September 1999, University College, London

    Demonstration of new possibilities of multilayer technology on resistive microstrip/ microdot detectors

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    The first successful attempts to optimize the electric field in Resistive Microstrip Gas Chamber and resistive microdot detectors using additional field shaping strips located inside the detector substrate are describedComment: Presented at the RD-51 mmini week, CERN, June 201

    The Development and Study of High-Position Resolution (50 micron) RPCs for Imaging X-rays and UV photons

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    Nowadays, commonly used Resistive Plate Chambers (RPCs) have counting rate capabilities of ~10E4Hz/cm2 and position resolutions of ~1cm. We have developed small prototypes of RPCs (5x5 and 10x10cm2) having rate capabilities of up to 10E7Hz/cm2 and position resolutions of 50 micron("on line" without application of any treatment method like "center of gravity"). The breakthrough in achieving extraordinary rate and position resolutions was only possible after solving several serious problems: RPC cleaning and assembling technology, aging, spurious pulses and afterpulses, discharges in the amplification gap and along the spacers. High-rate, high-position resolution RPCs can find a wide range of applications in many different fields, for example in medical imaging. RPCs with the cathodes coated by CsI photosensitive layer can detect ultraviolet photons with a position resolution that is better than ~30 micron. Such detectors can also be used in many applications, for example in the focal plane of high resolution vacuum spectrographs or as image scanners.Comment: 6 pages, 5 figures, other comment

    A study of breakdown limits in microstrip gas counters with preamplification structures

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    We have studied the charge and breakdown limits of Microstrip Gas Counters (MSGC's) with two different preamplification structures: the Gas Electron Multiplier (GEM) and the Parallel-Plate Avalanche Counter (PPAC). It was found that in both cases the breakdown limit was increased by 1-2 orders of magnitude compared to the bare MSGC and that this was due to the spreading of the primary electron cloud during pre-amplification. This spreading reduces the charge density in the final MSGC avalanche, permitting much higher total gains before streamers form. The real practical gain limitations in these two-stage detectors arose not from sparking, but from a loss of proportionality due to space charge effects.http://www.sciencedirect.com/science/article/B6TJM-3V8TV5X-34/1/126083510ba3bfd528bad96ccdbc08a
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