GEM-MIGAS Electron Multiplier Operation in Argon-Methane Mixtures
A Gas Electron Multiplier with a Micro-Induction Gap Amplifying Structure (GEM-MIGAS) is formed when a conventional GEM is operated with a short induction gap, typically 50 mum. A three-dimensional electric field simulation of a GEM-MIGAS detector was performed in order to evaluate the electric field profile in the different regions of the structure. Different electrostatic conditions were undertaken to forecast the detector performance in gas medium. An experimental study of GEM-MIGAS operating in an Ar/CH4 (90/10%) gas mixture, in pure CH4 and in pure Ar was carried out. Performance characteristics including charge gain and energy resolution for 5.9 keV X-rays are presented.
A concise review on THGEM detectors
Abstract We briefly review the concept and properties of the THick Gaseous Electron Multiplier (THGEM); it is a robust, high-gain gaseous electron multiplier, manufactured economically by standard printed-circuit drilling and etching technology. Its operation and structure resemble that of gaseous electron multiplier's (GEM's) but with 5–20-fold expanded dimensions. The millimeter-scale hole-size results in good electron transport and in large avalanche-multiplication factors, e.g. reaching 10 7 in double-THGEM cascaded single-photoelectron detectors. The multiplier's material, parameters and shape can be application-tailored; it can operate practically in any counting gas, including noble gases, over a pressure range spanning from 1 mbar to several bars; its operation at cryogenic (LAr) conditions was recently demonstrated. The high gain, sub-millimeter spatial resolution, high counting-rate capability, good timing properties and the possibility of industrial production capability of large-area robust detectors, pave ways towards a broad spectrum of potential applications; some are discussed here in brief.
Development and First Tests of GEM-Like Detectors With Resistive Electrodes
We have developed and tested several prototypes of GEM-like detectors with electrodes coated with resistive layers or completely made of resistive materials. These detectors can operate stably at gains close to 105. The resistive layers limit the energy of discharges appearing at higher gains thus making the detectors very robust. We demonstrated that the cathodes of some of these detectors could be coated by CsI or SbCs layers to enhance the detection efficiency for the UV and visible photons. We also discovered that such detectors can operate stably in the cascade mode and high overall gains (~106) are reachable. Applications in several areas, for example in RICH or in noble liquid TPCs are therefore possible. The first results from the detection of UV photons at room and cryogenic temperatures will be given.