Limits of a spatial resolution of the cascaded GEM based detectors

Spatial resolution of tracking detectors based on GEM cascades is determined in the simulation and measured. The simulation includes GEANT4 implemented transport of high energy electrons with careful accounting for atomic relaxation processes including emission of fluorescent photons and Auger elect...

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Bibliographic Details
Published in:Journal of instrumentation 2017-06, Vol.12 (6), p.C06015-C06015
Main Authors: Kudryavtsev, V.N., Maltsev, T.V., Shekhtman, L.I.
Format: Article
Language:English
Subjects:
Algorithms
Augers
CAD
Computer aided design
Computer simulation
Detectors
Deuterons
Electron beams
Electron clouds
Fluorescence
Gas mixtures
High energy electrons
Post-processing
Sensors
Simulation
Spatial resolution
Variations
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Summary:Spatial resolution of tracking detectors based on GEM cascades is determined in the simulation and measured. The simulation includes GEANT4 implemented transport of high energy electrons with careful accounting for atomic relaxation processes including emission of fluorescent photons and Auger electrons and custom post-processing taking into account diffusion, gas amplification fluctuations, the distribution of signals over readout electrodes, electronics noise and particular algorithm of final coordinate calculation (centre-of-gravity algorithm). The simulation demonstrates that the minimum of the spatial resolution of about 10–20 μm can be achieved with a gas mixture of Ar-CO2 (75%–25%) at a strip pitch in the range from 250 μm to 300 μm. At a larger pitch the resolution quickly degrades reaching 70–100 μm at a pitch of 450–500 μm. The reasons of such behavior are discussed and corresponding hypothesis is tested. Particularly, the effect of electron cloud modification due to a GEM operation is considered using the ANSYS and Garfield++ simulation programs. The detection efficiency and spatial resolution of low-material triple-GEM detectors for the DEUTERON facility at BINP are measured at the extracted beam facility of the VEPP-4M collider. One-coordinate resolution of two detectors for the DEUTERON facility is measured with a 2 GeV electron beam. The determined values of the detectors' spatial resolution is equal to 46.6 ± 0.1 μm and 38.5 ± 0.2 μm for orthogonal tracks in two detectors, respectively.
ISSN:1748-0221
1748-0221
DOI:10.1088/1748-0221/12/06/C06015