New observations with the gas electron multiplier (GEM) (original) (raw)
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The gas electron multiplier (GEM)
IEEE Transactions on Nuclear Science, 1997
We describe operating principles and results obtained with a new detector element: the Gas Electron Multiplier (GEM). Consisting of a thin composite sheet with two metal layers separated by a thin insulator, and pierced by a regular matrix of open channels, the GEM electrode, inserted on the path of electrons in a gas detector, allows the transfer of charge with
Charge amplification and transfer processes in the gas electron multiplier
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
We report the results of systematic investigations on the operating properties of detectors based on the gas electron multiplier (GEM). The dependence of gain and charge collection efficiency on the external fields has been studied in a range of values for the hole diameter and pitch. The collection efficiency of ionization electrons into the multiplier, after an initial increase, reaches a plateau extending to higher values of drift field the larger the GEM voltage and its optical transparency. The effective gain, fraction of electrons collected by an electrode following the multiplier, increases almost linearly with the collection field, until entering a steeper parallel plate multiplication regime. The maximum effective gain attainable increases with the reduction in the hole diameter, stabilizing to a constant value at a diameter approximately corresponding to the foil thickness. Charge transfer properties appear to depend only on ratios of fields outside and within the channels, with no interaction between the external fields. With proper design, GEM detectors can be optimized to satisfy a wide range of experimental requirements: fast tracking of minimum ionizing particles, good electron collection with small distortions in high magnetic fields, improved multi-track resolution and strong ion feedback suppression in large volume and time projection chambers.
Advances in the Micro-Hole & Strip Plate gaseous detector
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2003
We report on the performance of a new gaseous electron multiplier: the Micro-Hole & Strip Plate (MHSP). It consists of two independent charge-amplification stages in a single, double-sided micro-structured electrode, deposited on a thin insulating substrate. Charge gains in excess of 10 3 were obtained in a MHSP operated with soft X-rays in Ar/CO 2 (70/ 30). We present the results of a systematic study of the MHSP properties and those of a double-stage GEM+MHSP multiplier. Applications to gaseous photomultipliers are discussed. r
Journal of Instrumentation, 2018
We describe a new micro-pattern gas detector structure comprising a multi-layer hole-type multiplier (M-THGEM) combined with two in-built electrode meshes: the Multi-Mesh THGEM-type multiplier (MM-THGEM). Suitable potential differences applied between the various electrodes provide an efficient collection of ionization electrons within the MM-THGEM holes and a large charge avalanche multiplication between the meshes. Different from conventional hole-type multipliers (e.g. Gas Electron Multipliers-GEMs, Thick Gas Electron Multipliers-THGEMs, etc.), which are characterized by a variable (dipole-like) field strength inside the avalanche gap, electrons in MM-THGEMs are largely multiplied by a strong uniform field established between the two meshes, like in the parallel-plate avalanche geometry. The presence of the two meshes within the holes allows for the trapping of a large fraction of the positive ions that stream back to the drift region. A gas gain above 10 5 has been achieved for single photo-electron detection with a single MM-THGEM in Ar/(10%)CH 4 and He/(10%)CO 2 , at standard conditions for temperature and pressure. When the MM-THGEM is coupled to a conventional THGEM and used as first cascade element, the maximum achievable gains reach values above 10 6 in He/(10%)CO 2 , while the IBF approaches of 1.5% in the case of optimum detector-bias configuration. This IBF value is several times lower compared to the one obtained by a double GEM/THGEM detector (5-10%), and equivalent to the performance attained by a Micromegas detector.
Development and applications of the gas electron multiplier
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2001
The Gas Electron Multiplier (GEM) has been recently developed to cope with the severe requirements of high luminosity particle physics experimentation. With excellent position accuracy and very high rate capability, GEM devices are robust and easy to manufacture. The possibility of cascading two or more multipliers permits to achieve larger gains and more stable operation. We discuss major performances of the new detectors, particularly in view of possible use for high rate portal imaging and medical diagnostics.
Beam tests of the gas electron multiplier
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1999
We describe the results of systematic measurements, carried out with single and double GEM detectors with printed circuit read-out and having an active area of 10x10 cm 2 , both in the laboratory and in a high energy charged particles beam at CERN. Using fast analogue readout electronics, we demonstrate efficiencies for minimum ionizing particles close to 100%, with typical signal/noise ratios above 50 and up to 10 3 for the single and double GEM configuration, respectively, and a time resolution of 15 ns fwhm. Localization accuracies around 40 µm rms have been obtained for perpendicular tracks, degrading to 200 µm at 20° of incidence to the normal. Operated in a non-flammable gas mixture (argon-carbon dioxide), GEM detectors are robust, light and cheap to manufacture, and offer excellent performances and reliability suited for use in the harsh environments met at high luminosity colliders.
Construction of a Gas Electron Multiplier (GEM) Detector for Medical Imaging
arXiv (Cornell University), 2013
A prototype Gas Electron Multiplier (GEM) detector is under construction for medical imaging purposes. A single thick GEM of size 10x10 cm^2 is assembled inside a square shaped air-tight box which is made of Perspex glass. In order to ionize gas inside the drift field two types of voltage supplier circuits were fabricated, and array of 2x4 pads of each size 4x8 mm^2 were utilized for collecting avalanche charges. Preliminary testing results show that the circuit which produces high voltage and low current is better than that of low voltage and high current supplier circuit in terms of x-ray signal counting rates.
To cite this article: Rittirong, A. & Saenboonruang, K. (2018). Gains, uniformity and signal sharing in XY readouts of the 10 cm × 10 cm gas electron multiplier (GEM) detector. ABSTRACT: The gas electron multiplier (GEM) detector is a promising particle and radiation detector which has been greatly improved from previous gas detectors. In particular, the 10 cm × 10 cm GEM detector is utilised in applications including high-resolution tracking devices in nuclear and particle physics. With its operational and design simplicity, while still maintaining high quality, the GEM detector is suitable for both start-up and advanced research. This article reports simple procedures and results of an investigation of important properties of this detector, using current measurement and signal counting. Results show that gains of the GEM detector increase exponentially as voltages supplied to the detector increase and that the detector reaches full efficiency when the voltages are greater than −4100 V. In terms of signal sharing between X and Y strips of the read-out, the X strips, on the top layer of the read-out, collect larger signals. For the uniformity test, the GEM detector has slightly higher efficiencies at the centre of the detector. These results can be used for future reference and for better understanding of the GEM detector's characteristics.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2007
A Gas Electron Multiplier with Micro-Induction Gap Amplifying Structure (GEM-MIGAS) is formed when the induction gap of the GEM is set between 50 and 100 mm using kapton pillars spaced at regular intervals. This configuration combines the properties of a GEM and Micromegas, allowing operation in tandem to generate high charge gains. We measured the essential operational parameters of this system using argon-isobutane (IB) and helium-IB gas mixtures. The present short induction gap GEM was able to achieve effective gains exceeding 2 Â 10 4 using argon-IB and 10 5 using helium-IB mixtures. In view of the high gains achieved, particularly when using heliumbased gas mixtures, these studies confirmed the possibility of using the present system for high-performance sub-keV X-ray detection. r
Simulation and First Test of a Microdosimetric Detector Based on a Thick Gas Electron Multiplier
IEEE Transactions on Nuclear Science, 2000
We present design of a new microdosimetry detector based on thick gas electron multiplier (THGEM). A prototype detector was designed for a cylindrical sensitive volume with 5 mm diameter and 5 mm height. To optimize the avalanche gain, the electron avalanche process was modeled by varying THGEM thickness, hole diameter and high voltage bias for the tissue-equivalent propane gas. For a THGEM with 0.6 mm thickness and 0.3 mm hole diameter, the theoretical avalanche gain reached 200 at a 800 V THGEM bias. The prototype detector was fabricated and tested using the McMaster 7 Li(p n) neutron source.
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Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1999