We have developed and tested several prototypes of GEM-like detectors with electrodes coated with resistive layers: CuO or CrO. These detectors can operate stably at gains close to 10E5 and they are very robust. We discovered that the cathodes of these detectors could be coated by CsI layers and in such a way the detectors gain high efficiency for the UV photons. We also demonstrated that such detectors can operate stably in the cascade mode and high overall gains (~10E6) are reachable. This opens applications in several areas, for example in RICH or in noble liquid TPCs. Results from the first applications of these devices for UV photon detection at room and cryogenic temperatures are given.
Performances of several single gap (gas gap 2 mm) prototype Resistive Plate Chambers (RPC) made of high resistive (ρ \sim 1010 - 1012 Ω cm) bakelite, commercially available in India have been studied in recent times. To make the inner electrode surfaces smooth, a thin coating of silicone has been applied. An efficiency > 90% and time resolution \sim 2 ns (FWHM) have been obtained for both the streamer and the avalanche mode. The induced charge distributions of those silicone coated RPC are studied and the results are presented. A numerical study on the effect of surface roughness of the resist…
Gas electron multipliers (GEMs) have been overcoated with a high resistivity 10e14 - 10e15 Ohms / square amorphous carbon layer. The coating avoids charging up of the holes and provides a constant gain immediately after switching on independent of the rate. The gain uniformity across the GEM is improved. Coating opens the possibility to produce thick GEMs of very high gain.
We have developed prototypes of GEM-like detectors with resistive electrodes to be used as RICH photodetectors equipped with CsI photocathodes. The main advantages of these detectors are their intrinsic spark protection and possibility to operate at high gain (~10E5) in many gases including poorly quenched ones, allowing for the adoption of windowless configurations in which the radiator gas is also used in the chamber. Results of systematic studies of the resistive GEMs combined with CsI photocathodes are presented: its quantum efficiency, rate characteristics, long-term stability, etc. On th…
We have recently developed an innovative detector of photons and charged particles: a GEM-like gaseous amplification structure with resistive electrodes instead of commonly used metallic ones. This novel detector combines the best property of GEMs- the capability to operate in a cascaded mode and in poorly quenched gases - and of RPC: the protection against sparks. In this paper will shortly review our latest achievements in this direction, however the main focus will be given on a new advanced design that allows to build large area detectors manufactured by a screen printing technology. The p…
We report the application of the resistive anode readout method on a two dimensional imaging GEM detector. The resistive anode consists of $6\times6$ cells with the cell size $6~\mathrm{mm}\times6~\mathrm{mm}$. New electronics and DAQ system are used to process the signals from the 49 readout channels. The detector has been tested by using the X-ray tube (8~keV). The spatial resolution of the detector is about $103.46~\mathrm{μm}$ with the detector response part about $66.41~\mathrm{μm}$. The nonlinearity of the detector is less than $1.5\%$. A quite good two dimensional imaging capability is …
We report promising initial results obtained with new resistive-electrode GEM (RETGEM) detectors manufactured, for the first time, using screen printing technology. These new detectors allow one to reach gas gains nearly as high as with ordinary GEM-like detectors with metallic electrodes; however, due to the high resistivity of its electrodes the RETGEM, in contrast to ordinary hole-type detectors, has the advantage of being fully spark protected. We discovered that RETGEMs can operate stably and at high gains in noble gases and in other badly quenched gases, such as mixtures of noble gases w…
Cold Neutron Imaging and Efficiency Measurements with a Boron-10 Coated Double-GEM Detector
Department of Physics, University of Seoul（首尔大学物理系）；University of Seoul（首尔大学）；Institute of Basic Sciences, Seoul National University（首尔大学基础科学研究院）；Seoul National University（首尔大学）；Department of Physics, University of Turin（都灵大学物理系）；University of Turin（都灵大学）
In this work we show the operation and results of an X-ray fluorescence imaging system using a cascade of three gas electron multipliers (GEM) and a pinhole assembly. The detector operates in Ar/CO$_2$ (90/10) at atmospheric pressure, with resistive chains applied to the strip readout, which allow to use only five electronic channels: two for each dimension and a fifth for energy and trigger. The corrections applied to the energy spectra to compensate for small changes in the signal amplitude and also differences in gain throughout the sensitive area are described and the clear improvement of …
We describe here various detectors designs: GEM type, MICROMEGAStype, PPACtype as well as cascaded detectors made of a resistive mesh manufactured from a resistive Kapton foil, (20 microns thick, resistivity a few MOhm per square) by a laser drilling technique. As in any other micropattern detectors the maximum achievable gas gain of these detectors is restricted by the Raether limit, however, the resistive mesh makes them and the front end electronics fully spark protected. This approach could be an alternative or complimentary to the ongoing efforts in developing MICROMEGAS and GEMs with res…
The optimization of resistive anode for two dimensional imaging detectors which consists of a series of high resistive square pads surrounding by low resistive strips has been studied by both numerical simulations and experimental tests. It has been found that to obtain good detector performance, the resistance ratio of the pad to the strip should be larger than 5, the nonuniformity of the pad surface resistivity had better be less than $20\%$, a smaller pad width leads to a smaller spatial resolution and when the pad width is $6mm$, the spatial resolution ($σ$) can reach about $105μm$. Based …
Earlier we have developed and successfully tested a RICH detector prototype consisting in a CsI coated triple GEM operated in gas flushed mode In the given work, a modified version of this detector for a completely different application - fire safety- is presented. The detector operates in sealed mode and is combined with an optical system and a narrow band filter As a photosensitive element, a CsI photocathode coated with a thin layer of ethylferrocene was used. This detector is almost 1000 times more sensitive than the best commercial flame sensor; it has 100 times better time resolution and…
The India-based Neutrino Observatory (INO) is an approved multi-institutional experiment of India. It will use maximum 30,000 Resistive Plate Chamber (RPC) of size 2x2m as an active detector in which each will be sandwiched between two iron plates. Each RPC detectors will be made up of 3mm thick glass (or Bakelite) plates whose one surface will be coated with graphite paint to work as electrode. To achieve effective and uniform electric field, the coated graphite paint must have uniform distribution over the glass surface. Uniformity can be demonstrated by measuring the surface resistance of t…
The occurrence of electrical discharges in gas detectors restricts their dynamic range and degrades their performance. Among the different methods developed to mitigate discharge effects, the use of resistive materials in the detector assembly was found to be very effective. In this work, we present the results of a comparative study of electrical discharges in Thick-GEM-based WELL-type detectors - with and without resistive elements. We present a new method to measure discharges in the resistive-detector configurations; it allows demonstrating, for the first time, the occurrence of discharges…
In this work we characterized a X-ray position sensitive gaseous detector based in a triple stack of gas electron multipliers (GEM). The readout circuit is divided in 256 strips for each dimension and using a resistive chain interconnecting the strips, we are able to reconstruct the radiation interaction points by resistive charge division. The detector achieved gains above $10^4$, energy resolution of 15.28% (FWHM) for 5.9keV X-rays, and position resolution of 1.2mm, while operating in Ar/CO$_2$(90/10) at atmospheric pressure.
Micro-pattern gas detectors, such as the Gas Electron Multiplier (GEM) and the Micromegas need narrow high density anode readout elements to achieve good spatial resolution. A high-density anode readout would require an unmanageable number of electronics channels for certain potential micro-detector applications such as the Time Projection Chamber. We describe below a new technique to achieve good spatial resolution without increasing the electronics channel count in a modified micro-detector outfitted with a high surface resistivity anode readout structure. The concept and preliminary measure…
A new family of spark-protected micropattern gaseous detectors is introduced: a 2-D sensitive restive microstrip counter and hybrid detectors, which combine in one design a resistive GEM with a microstrip detector. These novel detectors have several important advantages over other conventional micropattern detectors and are unique for applications like the readout detectors for dual phase noble liquid TPCs and RICHs.
The spherical proportional counter is a gaseous detector used in a variety of applications, including direct dark matter and neutrino-less double beta decay searches. The ACHINOS multianode structure is a read-out technology that overcomes the limitations of single-anode read-out structures for large-size detectors and operation under high pressure. A resistive ACHINOS is presented, where the 3D printed central component is coated in a Diamond-Like Carbon (DLC) layer. The production and testing of the structure, in terms of stability and resolution, is described. Further applications in fundam…
The paper summarizes our latest progress in the development of newly introduced micro pattern gaseous detectors with resistive electrodes. These resistive electrodes protect the detector and the front-end electronics in case of occasional discharges and thus make the detectors very robust and reliable in operation. As an example, we describe in greater detail a new recently developed GEM-like detector, fully spark-protected with electrodes made of resistive kapton. We discovered that all resistive layers used in these studies (including kapton), that are coated with photosensitive layers, such…
We have developed and tested several new designs of GEM detectors with micropattern electrodes manufactured by microelectronic technology. In one design, the inner layer of the detector electrode consists of thin metallic strips and the outer layer is made of a resistive grid manufactured by a screen printing technology. In other designs, the electrodes were made of metallic strips fed by HV via micro-resistors manufactured by a screen printing technology. Due to these features, the new detectors have several important advantages over conventional GEMs or ordinary thick GEMs. For example, the …
To extend the acceptance of the CMS muon spectrometer to the region 2.4 $<|η|<$ 2.8, stacks of triple-GEM chambers, forming the ME0 station, are planned for the CMS Phase 2 Upgrade. These large-area micro-pattern gaseous detectors must operate in a challenging environment with expected background particle fluxes up to 150 kHz/cm$^2$. Unlike traditional non-resistive gaseous detectors, the rate capability of such triple-GEM detectors is limited not by space charge effects, but by voltage drops on the chamber electrodes due to avalanche-induced currents flowing through the resistive protection c…
The properties of thick GEM-like (TGEM) gaseous electron multipliers, operated at 1-740 Torr are presented. They are made of a G-10 plate, perforated with millimeter-scale diameter holes. In single-multiplier elements, effective gains of about 104, 106, and 105 were reached at respective pressures of 1, 10 Torr isobutane and 740 Torr Ar/5%CH4, with pulse rise-times in the few nanosecond scale. The high effective gain at atmospheric pressure was measured with a TGEM coated with a CsI photocathode. The detector was operated in single and cascaded modes. Potential applications in ion and photon d…
The fast timing MPGD is a micro-pattern gaseous detector conceived for achieving sub-nanosecond time resolution while maintaining the ability to instrument large areas in high-rate environments; applications of such technology are perspected in high-energy physics experiments at future colliders and medical diagnostics with time-of-flight methods. This work shows the systematic studies carried on an FTM prototype on the performance of GEM foils coated with resistive DLC films, whose development is essential for the FTM operation. The resistive foil performance has been tested with several gas …
We describe the most recent efforts made by various groups in implementing resistive electrodes in micropattern gaseous detectors with the aim to combine in the same design the best features of RPCs (for the example, their robustness and spark protection property) with the high granularity and thus the good position resolution offered by microelectronic technology. In the stream of this activity, we have recently developed two novel detectors with resistive electrodes: one was based on resistive micromeshes and the second one is a MSGC with resistive electrodes. We have demonstrated that the r…
Single gap (gas gap 2 mm) bakelite Resistive Plate Chamber (RPC) modules of various sizes from 10 cm \times 10 cm to 1 m \times 1 m have been fabricated, characterized and optimized for efficiency and time resolution. Thin layers of different grades of silicone compound are applied to the inner electrode surfaces to make them smooth and also to reduce the surface resistivity. In the silicone coated RPCs an efficiency > 90% and time resolution \sim 2 ns (FWHM) have been obtained for both the streamer and the avalanche mode of operation. Before fabrication of detectors the electrical properties …
In the last few years our group have focused on developing various designs of spark-protected micropattern gaseous detectors featuring resistive electrodes instead of the traditional metallic ones: resistive microstrip counters, resistive GEM, resistive MICROMEGAS. These detectors combine in one design the best features of RPCs (spark-protection) and micropattern detectors (a high position resolution). In this paper we report the progress so far made in developing other types of resistive micropattern detectors: a microdot-microhole detector and a microgap-microstrip detector. The former detec…
The performance of thick GEMs (THGEMs) was compared to that of thin GEMs in two-phase Ar avalanche detectors, in view of their potential application in coherent neutrino-nucleus scattering, dark-matter search and in other rare-event experiments. The detectors comprised a 1 cm thick liquid-Ar layer followed by either a double-THGEM or a triple-GEM multiplier, operated in the saturated vapor above the liquid phase. Three types of THGEMs were studied: those made of G10 and Kevlar and that with resistive electrodes (RETHGEM). Only the G10-made THGEM showed a stable performance in two-phase Ar with…
A large volume Time Projection Chamber (TPC) is being considered for the central charged particle tracker for the detector for the proposed International Linear Collider (ILC). To meet the ILC-TPC spatial resolution challenge of ~100 microns with a manageable number of readout pads and channels of electronics, Micro Pattern Gas Detectors (MPGD) are being developed which could use pads comparable in width to the proportional-wire/cathode-pad TPC. We have built a prototype GEM readout TPC with 2 mm x 6 mm pads using the new concept of charge dispersion in MPGDs with a resistive anode. The depend…
In this study we present first results from a new detector of UV photons: a thick gaseous electron multiplier (GEM) with resistive electrodes, combined with CsI or CsTe/CsI photocathodes. The hole type structure considerably suppresses the photon and ion feedback, whereas the resistive electrodes protect the detector and the readout electronics from damage by any eventual discharges. This device reaches higher gains than a previously developed photosensitive RPC and could be used not only for the imaging of UV sources, flames or Cherenkov light, for example, but also for the detection of X-ray…
For its ease manufacturing, flexible geometry, and cheap manufacturing cost, the gas electron multiplier (GEM) detector can be used as an x-ray image sensor. For this purpose, we acquired relative detection efficiencies and suggested a method to increase the detection efficiency in order to study the possibility of GEM detector as an x-ray image sensor. The GEM detector system is composed of GEM foils, the instrument system, the gas system, and the negative power supply. The instrument system consists of the A225 charge sensitive preamp, A206 discriminator, and MCA8000D multichannel analyzer. …
The Gas Electron Multiplier (GEM) is a new age detector, which can handle the high flux of particles. The GEM foil, which is constructed using 50$μ$m highly insulating foil (Kapton/Apical) coated with 5$μ$m layers of copper, on both sides, with a network of specifically shaped holes is the major component of these detectors. The European Center for Nuclear Research (CERN) has been the sole supplier of the GEM foils until recently when a few other companies started manufacturing GEM foils under the transfer of technology (TOT) agrement from CERN. Techtra is one such company in Europe which gain…
An innovative photosensitive gaseous detector, consisting of a GEM like amplification structure with double layered electrodes (instead of commonly used metallic ones) coated with a CsI reflective photocathode, is described. In one of our latest designs, the inner electrode consists of a metallic grid and the outer one is made of resistive strips; the latter are manufactured by a screen printing technology on the top of the metallic strips grid The inner metallic grid is used for 2D position measurements whereas the resistive layer provides an efficient spark protected operation at high gains …
We report on recent advances in the operation of bubble-assisted Liquid Hole Multipliers (LHM). By confining a vapor bubble under or adjacent to a perforated electrode immersed in liquid xenon, we could record both radiation-induced ionization electrons and primary scintillation photons in the noble liquid. Four types of LHM electrodes were investigated: a THGEM, standard double-conical GEM, 50 $μ$m-thick single-conical GEM (SC-GEM) and 125 $μ$m-thick SC-GEM - all coated with CsI photocathodes. The 125 $μ$m-thick SC-GEM provided the highest electroluminescence (EL) yields, up to ~400 photons p…
The Helium-3 shortage and the growing interest in neutron science constitute a driving factor in developing new neutron detection technologies. In this work, we report the development of a double-GEM detector prototype that uses a $^{10}$B$_4$C layer as a neutron converter material. GEANT4 simulations were performed predicting an efficiency of 3.14(10) %, agreeing within 2.7 $σ$ with the experimental and analytic detection efficiencies obtained by the detector when tested in a 41.8 meV thermal neutron beam. The detector is position sensitive, equipped with a 256+256 strip readout connected to …
Systematic investigations including both simulation and prototype tests have been done about the interpolating resistive readout structure with GEM (Gaseous Electron Multiplier) detector. From the simulation, we have a good knowledge of the process of charges diffusion on the surface of the readout plane and develop several reconstruction methods to determine the hit position. The total signal duration time of a typical event with the readout structure is about several hundred nanoseconds, which implied an ideal count rate up to 106Hz. A stable worked prototype was designed and fabricated afte…
A simple X-ray imaging system using off-the-shelf electronics and simple reconstruction algorithms aiming a spatial resolution of 1.7 mm ($\sim 3\,\%$ of the detector length) is described in this work. For this, two 100 cm$^2$ Gas Electron Multiplier (GEM) foils with a thickness of 100 μm (2-fold thicker than the standard ones) were immersed in a mixture of argon and carbon dioxide (70:30). The charge readout with 2D position determination was done with resistive charge division. Due to their higher thickness with respect to the standard GEMs, the 100 μm thick GEM foils were found to be less p…
In this work we present a novel idea for a compact spark-protected single amplification stage Micro-Pattern Gas Detector (MPGD). The detector amplification stage, realized with a structure very similar to a GEM foil, is embedded through a resistive layer in the readout board. A cathode electrode, defining the gas conversion/drift gap, completes the detector mechanics. The new structure, that we call Resistive-WELL (R-WELL), has some characteristics in common with previous MPGDs, such as C.A.T. and WELL, developed more than ten years ago. The prototype object of the present study has been reali…
GEM are widely used as amplification stages in gaseous detectors exposed to high rates. The GEM consists of a polyimide foil which is coated by two thin copper layers. Charges collected into the holes or created during the amplification process may adhere to the polyimide part inside the holes. This is often accompanied by a change of the effective gain. The effect is commonly known as the charging-up effect. This work presents a systematic investigation of the effect under well-controlled and monitored conditions for a single standard GEM foil in Ar/CO$_2$ (90/10) gas for varying rates of X-r…
μRWELL-PICOSEC: Precision Timing with Resistive Micro-Well Detector
Thomas Jefferson National Accelerator Facility（托马斯·杰斐逊国家加速器设施）；IRFU, CEA, Université Paris-Saclay（IRFU, 法国原子能和替代能源委员会, 巴黎萨克雷大学）；Department of Physics, Aristotle University of Thessaloniki（塞萨洛尼基亚里士多德大学物理系）；Center for Interdisciplinary Research and Innovation (CIRI-AUTH)（跨学科研究与创新中心）；Department for Medical Physics, Ludwig Maximilian University of Munich（慕尼黑路德维希-马克西米利安大学医学物理系）；European Organization for Nuclear Research (CERN)（欧洲核子研究组织）；Dipartimento di Fisica, Università di Pavia（帕维亚大学物理系）；INFN Sezione di Pavia（意大利国家核物理研究所帕维亚分部）；Department of Physics and Astronomy, Stony Brook University（石溪大学物理与天文学系）；Institute of Nuclear and Particle Physics, NCSR Demokritos（国家科学研究中心德谟克利特研究所核与粒子物理研究所）
We have developed a new detector of photons and charged particles- a hole-type structure with electrodes made of a double layered resistive material: a thin low resistive layer coated with a layer having a much higher resistivity. One of the unique features of this detector is its capability to operate at high gas gains (up to 10E4) in air or in gas mixtures with air. They can also operate in a cascaded mode or be combined with other detectors, for example with GEM. This opens new avenues in their applications. Several prototypes of these devices based on new detectors and oriented on practica…
New Micromegas (Micro-mesh gaseous detectors) are being developed in view of the future physics projects planned by the COMPASS collaboration at CERN. Several major upgrades compared to present detectors are being studied: detectors standing five times higher luminosity with hadron beams, detection of beam particles (flux up to a few hundred of kHz/mm^{2}, 10 times larger than for the present Micromegas detectors) with pixelized read-out in the central part, light and integrated electronics, and improved robustness. Two solutions of reduction of discharge impact have been studied, with Microme…
We have developed a cost effective technology for manufacturing various layouts of micropattern gaseous detectors for a wide range of applications. Such devices feature resistive electrodes interfaced to a network of thin readout strips/electrodes. The following three examples of such innovative designs and their applications will be presented: a prototype of a novel double-phase LAr detector with a CsI photocathode immersed inside the LAr, a CsI-RICH detector prototype for ALICE upgrade and GEM-like sensors for environmental safety/security applications.
The muon detection system of the Compact Muon Solenoid experiment at the CERN Large Hadron Collider is based on different technologies for muon tracking and triggering. In particular, the muon system in the endcap disks of the detector consists of Resistive Plate Chambers for triggering and Cathode Strip Chambers for tracking. At present, the endcap muon system is only partially instrumented with the very forward detector region remaining uncovered. In view of a possible future extension of the muon endcap system, we report on a feasibility study on the use of Micro-Pattern Gas Detectors, in p…
The present generation of Micro-Pattern Gaseous Detectors (MPGDs) are radiation hard detectors, capable of detecting efficiently particle rates of several MHz/cm$^2$ , while exhibiting good spatial resolution ($\leq$ 50 $μ$m) and modest time resolution of 5-10 ns, which satisfies the current generation of experiments (High Luminosity LHC upgrades of CMS and ATLAS) but it is not sufficient for bunch crossing identification of fast timing systems at FCC- hh. Thanks to the application of thin resistive films such as Diamond-Like Carbon (DLC) a new detector concept was conceived: Fast Timing MPGD …
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 amplifi…
In this paper we present irradiation measurements performed to select a transparent anode substrate that best meets the requirements of an optical readout for a novel detector, the LaGEMPix. The modification of the optical properties of the material due to proton irradiation were studied in soda-lime, fused quartz and fused silica glasses coated with an Indium Tin Oxide layer. The irradiations were performed using the research Beam Transfer Line (BTL) of the IBA Cyclone 18 MeV cyclotron of the Bern University Hospital (Inselspital). We recorded visible scintillation light generated by proton i…
Graphene is a single layer of carbon atoms arranged in a honeycomb lattice with remarkable mechanical and electrical properties. Regarded as the thinnest and narrowest conductive mesh, it has drastically different transmission behaviours when bombarded with electrons and ions in vacuum. This property, if confirmed in gas, may be a definitive solution for the ion back-flow problem in gaseous detectors. In order to ascertain this aspect, graphene layers of dimensions of about 2x2cm$^2$, grown on a copper substrate, are transferred onto a flat metal surface with holes, so that the graphene layer …
The architecture of the novel MPGD-based photon detectors of COMPASS RICH-1 consists in a large-size hybrid MPGD multilayer layout combining two layers of Thick-GEMs and a bulk resistive MICROMEGAS. Concerning biasing voltage, the Thick-GEMs are segmented in order to reduce the energy released in case of occasional discharges, while the MICROMEGAS anode is segmented in pads individually biased at positive voltage, while the micromesh is grounded. In total, there are ten different electrode types and more than 20000 electrodes supplied by more than 100 HV channels. Commercial power supply units…
The novel MPGD-based photon detectors of COMPASS RICH-1 consist of large-size hybrid MPGDs with multi-layer architecture including two layers of Thick-GEMs and a bulk resistive MicroMegas. The top surface of the first THGEM is coated with a CsI film which also acts as photo-cathode. These detectors have been successfully in operation at COMPASS since 2016. Concerning bias-voltage supply, the Thick-GEMs are segmented in order to reduce the energy released in case of occasional discharges, while the MicroMegas anode is segmented into pads individually biased with positive voltage while the micro…
