Gas Electron Multiplier Detector Research Articles

The CGEM-IT readout chain

An innovative Cylindrical Gas Electron Multiplier (CGEM) detector is under construction for the upgrade of the inner tracker of the BESIII experiment. A novel system has been worked out for the readout of the CGEM detector, including a new ASIC, dubbed TIGER -Torino Integrated GEM Electronics for Readout, designed for the amplification and digitization of the CGEM output signals. The data output by TIGER are collected and processed by a first FPGA-based module, GEM Read Out Card, in charge of configuration and control of the front-end ASICs. A second FPGA-based module, named GEM Data Concentrator, builds the trigger selected event packets containing the data and stores them via the main BESIII data acquisition system. The design of the electronics chain, including the power and signal distribution, will be presented together with its performance.

Feasibility study of TPC detector at high luminosity Z pole on the circular collider

With the development of the circular collider, it is necessary to make accurate physics experimental measurements of particle properties at higher luminosity [Formula: see text] pole. Micro-pattern gaseous detectors (MPGDs), which contain gaseous electron multiplier (GEM) and micro-mesh gaseous structures (Micromegas), have excellent potential for development as the readout devices of the time projection chamber (TPC) tracker detector. To meet the updated physics requirements of the high luminosity [Formula: see text] from the preliminary concept design report (preCDR) to concept design report (CDR) at the circular electron–positron collider (CEPC). In this paper, the space charge distortion of the TPC detector is simulated with the CEPC beam structure. Using the multi-physics simulation software package, the distribution of ion estimated by Geant4 is used as the input for the differential equation, and the relationship between the ion density distribution and electric field in the detector chamber is simulated. These simulation results show that the maximum deviation for Higgs [Formula: see text] meets the performance requirements in CEPC TPC detector at the high luminosity [Formula: see text] pole, while it is still a considerable challenge for [Formula: see text] pole, with the maximum deviation [Formula: see text]. According to the previous developments, the cascaded structure of GEM and Micromegas detector has been measured. The new considerations of the detector’s requirements were given, the gain needs to be reached to about 2000 with IBF[Formula: see text]Gain under 0.1, and IBF means the ions back flow ratio of the detector. The pixel TPC is a potential option to replace the traditional MPGDs with the low gain, low occupancy, and outstanding pattern recognition. Finally, some update parameters and experiments results were compared.

R&D of gas filled detectors for high energy physics experiments


 
 
 Bose Institute is Asia’s first modern research centre devoted to interdisciplinary research and bears a century old tradition of research excellence. In the experimental high-energy physics (EHEP) detector laboratory of Bose Institute, Kolkata, we are working on the R&D of Gas Electron Multiplier (GEM), straw tube detector for future heavy ion physics experiments and also developing low resistive bakelite Resistive Plate Chamber (RPC), keeping in mind high particle rate handling capacity. The main goal of our research program is the stability study and ageing study of gaseous detectors mentioned above. In this review article, the details of the R&D program of GEM detector, straw tube and RPC detectors carried out during the last five years is reported. 
 
 

Attenuation of electromagnetic radiation in Nuclear Track Detectors

A systematic study of the attenuation (absorption) of electromagnetic radiation in Nuclear Track Detectors (NTDs) is carried out. The attenuation of gamma rays, X-rays, UV and visible radiations in NTDs are investigated using NaI(Tl) detector, Gas Electron Multiplier (GEM) detector and UV-Vis spectrophotometer respectively.The values of some important parameters (e.g., mass attenuation coefficient, optical depth) of three commercially available NTDs (PET, Makrofol® and CR-39®), at the relevant regions of the electromagnetic spectrum, are determined. The details of the experimental techniques and the results are also presented in this report.

Charge sharing in single and double GEMs

The Gas Electron Multiplier (GEM) has become a widely used technology for high-rate particle physics experiments like COMPASS, LHCb and are going to be used for the upgrade of the detectors of other experiments, such as ALICE TPC. Radiation hardness, ageing resistance and stability against discharges are main criteria for long-term operation of such detectors in high-rate experiments. In particular, discharge is a serious issue as it may cause irreversible damages to the detector as well to the readout electronics. The charge density inside the amplification region is one of the limiting factors for detector stability against discharges. By using multiple devices, and thus sharing the electron multiplication in different stages, the maximum sustainable gain can be increased by several orders of magnitude. A common explanation for this is connected to the transverse electron diffusion, which causes widening of the electron cloud and reducing the charge density in the last multiplier. This has been verified experimentally [1] but numerical investigations, as far as we know, are scarce. In our work, we are using Garfield simulation framework as a tool to extract the information related to the transverse size of the propagating electron cloud and thus to estimate the charge density in the GEM holes for multiple stages. For a given gas mixture, we will present the initial results of charge sharing using single and double GEM detectors under different electric field configurations and its effect on other measurable detector parameters such as single point position resolution.

Multichannel gas electron multiplier based soft x-ray field-programmable gate array measurement system for W-Environment in Steady-state Tokamak (WEST): Hardware, installation, and first plasma acquisition.

The work describes a novel approach to the design of a fast, multichannel measurement system for plasma diagnostics [A. Wojenski et al., Fusion Eng. Des. 123, 727 (2016)]. Its main scope is to provide measurements of soft X-ray (SXR) emission during plasma phenomena at the W-Environment in Steady-state Tokamak (WEST), especially for monitoring and tracing tungsten impurities. This paper describes the vertical Gas Electron Multiplier (GEM) camera installed at the WEST [M. Chernyshova et al., J. Instrument. 10, P10022 (2015)]. The designed GEM detector readout board has more than 100 channels, resulting in high-performance requirements for the data acquisition and processing system. The novel system construction approach is that the unit works on the raw signals providing a high quality of the data, especially in the scope of pileup effect analysis. In the case of doubtful results, the source data can be easily reviewed offline. The data selection and transmission are done in Field-Programmable Gate Arrays (FPGAs) on the custom boards with the custom Peripheral Component Interconnect (PCI)-Express Gen2 switch that allows us to register signals from multiple FPGAs and then process the data by complex algorithms [G. Kasprowicz et al., J. Fusion Energy 38, 480 (2019)]. The firmware is replaceable and different working modes can be applied (some under verification): global trigger mode, high-speed data serialization, and extended signal registration. Low level optimized central processing unit software for data readout was also designed [P. Linczuk et al., J. Instrum. 14, C05001 (2019)]. The installation of the system is described due to complex system components' distribution. The first results of the successful acquisition of the plasma at the WEST are discussed. The corresponding SXR energy and topology spectra were computed. Those are the first technical measurements of the system to ensure verification of data quality.

Characterization and calibration of a triple-GEM detector for medical dosimetry

We characterized and calibrated a triple Gas Electron Multiplier (triple-GEM) detector, and studied its possible applications in medical dosimetry. The response to various sources of radiation was analyzed, and its gain, energy resolution, and time resolution were calculated. Then, radiation doses from an Iron-55 source and a medical portable X-ray machine were measured, obtaining the calibration factor for the GEM detector by comparison with reference values.We found an energy resolution of 19.5%, a time resolution of 40 ns, and a maximum gain of 5×106. The detector’s response to dose measurements was linear, with a calibration coefficient of 1.13×104 for different sources of radiation. It was concluded that GEM detectors can be reliably used as dosimeters in nuclear medicine and radiology.

Dosimetry of Thermal Neutron Beamlines at a Pulsed Spallation Source for Application to the Irradiation of Microelectronics

Gas electron multiplier (GEM) detectors and activation foils have been used for dosimetry of thermal beamlines of a pulsed neutron source. The first is an active detector that performs measurements using the time-of-flight technique, taking advantage of the pulsed nature of the source. The same detector has been used successfully to measure the profiles of the beams. The second is a passive irradiation method that independently confirms the measured fluxes of equipment materials and mechanics analyzer (EMMA) and rotating analyzer crystal (X) spectrometer (ROTAX) beamlines of the ISIS neutron source. They feature different thermal spectra, the first being moderated with water (300 K) and the second with liquid methane (100 K). These two characterized beamlines have been used for the irradiation of microelectronics for single-event effect testing using a reference static random access memory (SRAM) module. It is shown that results are consistent and that a correction factor must be applied to scale the results on the cold beamline to the one at room temperature.

Thin cathode glass gas electron multiplier detector for carbon beam dose imaging

ABSTRACT An optically read-out glass gas electron multiplier (G-GEM) detector is expected to simplify complicated quality assurance measurements for hadron therapies by imaging the dose distribution of the incident beam. However, the effect of secondary particles from the detector itself has not been well studied. In this paper, we evaluate a design that reduces the secondary particles from the cathode of a G-GEM detector. Specifically, we assembled detectors with thin cathodes and assessed their effect on the secondary particle production in simulations and experiments. The experiments were carried out under 290 MeV/u 12C ion bombardment at the Heavy Ion Medical Accelerator in Chiba. The clinical intensity of the thin cathode detector was compared with that of a conventional thick cathode G-GEM detector. The improved chamber design reduced the dose contributions of secondary particles from the cathode without degrading the dose imaging performance.

The upgrade of the ALICE TPC with GEMs and continuous readout

The upgrade of the ALICE TPC will allow the experiment to cope with the high interaction rates foreseen for the forthcoming Run 3 and Run 4 at the CERN LHC. In this article, we describe the design of new readout chambers and front-end electronics, which are driven by the goals of the experiment. Gas Electron Multiplier (GEM) detectors arranged in stacks containing four GEMs each, and continuous readout electronics based on the SAMPA chip, an ALICE development, are replacing the previous elements. The construction of these new elements, together with their associated quality control procedures, is explained in detail. Finally, the readout chamber and front-end electronics cards replacement, together with the commissioning of the detector prior to installation in the experimental cavern, are presented. After a nine-year period of R&D, construction, and assembly, the upgrade of the TPC was completed in 2020.

High level verification of the VFAT3 ASIC for CMS GEM detectors

A front-end readout chip VFAT3 was designed for the muon detector gas electron multipliers (GEM). GEMs were installed at the Compact Muon Solenoid (CMS) experiment of the Large Hadron Collider (LHC) at CERN for the high luminosity upgrade. The design of the VFAT3 uses 790 analog and 172 digital blocks which are highly integrated, thus it is crucial to ensure that the different blocks work together and the chip works as a whole. Mixed signal simulation methods were used to verify the high level functionality. Trigger latencies of 125, 150, 175 and 225 ns were found for front-end peaking times of 25, 50, 75 and 100 ns, respectively. The maximum trigger rate for reading out standard data packets was found to be 1.7 MHz. Results of the VFAT3 high level verification are presented and the simulation methods described.

Fabrication and Characterization of Gaseous Detector for the identification of High Energy Particles.

There is a vast range of gases which get ionized, produce electron-ion pairs, on the passage of high energy charged particles. Such gases are extensively used in experiments such as LHC, Belle-II, RHIC, DAFNE, etc which produce high energy particles. Panjab University established a detector assembly and characterization laboratory dedicated to gaseous detectors such as Resistive Plate Chamber (RPC) and Gas Electron Multiplier (GEM) for the LHC experiment. Here, we present the recent work on the fabrication and characterizations of the GEM detector at Panjab University.

A density-based clustering algorithm for the CYGNO data analysis

Time Projection Chambers (TPCs) working in combination with Gas Electron Multipliers (GEMs) produce a very sensitive detector capable of observing low energy events. This is achieved by capturing photons generated during the GEM electron multiplication process by means of a high-resolution camera. The CYGNO experiment has recently developed a TPC Triple GEM detector coupled to a low noise and high spatial resolution CMOS sensor. For the image analysis, an algorithm based on an adapted version of the well-known DBSCAN was implemented, called iDBSCAN. In this paper a description of the iDBSCAN algorithm is given, including test and validation of its parameters, and a comparison with DBSCAN itself and a widely used algorithm known as Nearest Neighbor Clustering (NNC). The results show that the adapted version of DBSCAN is capable of providing full signal detection efficiency and very good energy resolution while improving the detector background rejection.

Assembly and performance study of a triple gas electron multiplier with a 55Fe source

In this work, a process for the assembly of a standard triple Gas Electron Multiplier detector and the study of the main variables was made at the Universidad Antonio Nariño, Colombia, detectors laboratory. The triple gas electron multiplier was tested with Ar/CO2 mixtures in proportions of 70/30%, 80/20% and 90/10% using a 55Fe X-ray source (5.9 keV). The energy spectrum, energy resolution, effective gain and ionization rate were analyzed according to the applied voltage and the Ar/CO2 gas mixture. The Universidad Antonio Nariño, Colombia, triple gas electron multiplier detector obtained an energy resolution of up to 19% and an effective gain close to 104; where the detection efficiency is approximately 95%. These results were compared with other studies to check the triple gas electron multiplier performance.

Triple-GEM detectors operation under gas recirculation in high-rate radiation environment

At the CERN LHC experiments, several gaseous detector technologies are operated in gas recirculation mode to lower operational costs and gas emissions. In the next years, Micro Pattern Gaseous Detector (MPGD) technologies will be largely implemented in the LHC experiments, with dedicated gas systems, and they will experience a significantly increased background radiation rate, especially in the HL-LHC phase. It is therefore fundamental to study MPGD operated with LHC gas systems, especially under gas recirculation, to be able to guarantee their safe long-term operation. In this context, the performance of Gas Electron Multiplier (GEM) detectors operated in gas recirculating systems have been studied at the CERN Gamma Irradiation Facility (GIF++), which provides an intense gamma irradiation along with a Muon beam from the SPS accelerator. Triple-GEM detectors performance has been studied in relation to operation stability during long-term high rate irradiation, as well as in terms of Muon detection efficiency with different gamma background rates. Both tests were realized with various gas mixtures and gas system conditions. A complete overview of the results obtained at the GIF++ is presented, showing the successful operation of Triple-GEM detectors during long-term high-rate irradiation and good Muon detection efficiency in LHC HL-like background radiation.

Study of charging up effect in a triple GEM detector

The advancement of Micro Pattern Gaseous Detector technology offers us different kinds of detectors with good spatial resolution and high rate capability and the Gas Electron Multiplier (GEM) detector is one of them. Typically GEM is made up of a thin polyimide foil having a thickness of 50 micrometers with 5 micrometers copper cladding on top and bottom sides. The presence of polyimide changes the gain of the detector under the influence of external radiation and the phenomenon is referred to as the charging up effect. The charging up effect is investigated with a double mask triple GEM detector prototype with Ar/CO2 gas mixture in 70/30 ratio under continuous irradiation from a strong Fe55 X-ray source. The detailed method of measurements and the test results are presented in this article.

Status of the GEM/CSC tracking system of the BM@N experiment

Baryonic Matter at Nuclotron (BM@N) is a fixed target experiment at the NICA accelerator complex (JINR) aiming at studies of nuclear matter in relativistic heavy ion collisions. Triple-GEM (Gas electron multiplier) detectors have been identified as suitable for the BM@N central tracking system, which is located inside the analyzing magnet. A cathode strip chamber (CSC) is mounted outside the magnet to improve the momentum resolution of the experimental setup. Seven GEM detectors and one CSC are integrated into the BM@N experimental setup and data acquisition system. The structure of the BM@N GEM and CSC detectors and the results of the study of their characteristics are presented. The full configuration of the GEM/CSC tracking system is shortly reviewed.

Production and installation of the first GEM station in CMS

In 2017 the LHC reached the record beam luminosity 2 ⋅ 1034 cm−2 s−1, around a factor of two beyond the LHC design value. In December 2018 the Large Hadron Collider (LHC) entered the LS2 phase (Long Shutdown 2), which will last until beginning of 2021, in which the maintainance and upgrade program of LHC and the other smaller accelerators is scheduled. To cope with this and also looking at the following LHC phase in which the luminosity will be increased to 5 ⋅ 1034 cm−2 s−1 the LHC experiments must be upgraded as well. In this context the muon subsystem of the CMS experiment began installing the first GEM based detector station (GE1/1) in July 2019, almost 5 meters from the point of interaction. GE1/1 will consist of 144 triple Gas Electron Multiplier (GEM) detectors, which will work together with the Cathode Strip Chamber (CSC) station ME1/1, improving tracking and triggering of muons produced in the pseudorapidity range of 1.6 < |η| < 2.15. The installation in CMS is now underway at a good pace. The first 72 chambers have been installed together with their services (gas, cooling, low voltage and high voltage etc.) while the completion of the station is foreseen in spring 2020. This contribution will summarize the detector design along with the steps a detector must pass before being approved for the installation in CMS. The status of the operations will be presented, together with the tools developed to monitor the detector parameters during installation. Finally the plans for the installation and commissioning of the entire project will be outlined.

Drift velocity measurement in gas electron multiplier detectors for application in a time projection chamber polarimeter.

Drift velocity of electrons is an important parameter when signal formation is considered in detectors. In micro-pattern gas detectors such as the gas electron multiplier (GEM), the drift velocity is affected by non-uniform electric field configurations. In the context of x-ray polarimetric application of GEM, where the time projection chamber (TPC) configuration is used, the drift velocity plays an important role in forming time binned images. The accuracy of these images governs the information on polarization of incident photons. The work presented here proposes an experimental method to determine the drift velocity of electrons in such a gas detector. The gas under study is Ne/DME (50/50). The experimental setup comprising a single GEM is similar to the TPC polarimeter configuration. The effect of gas pressure and electric field on drift velocity is presented in the work. It is encouraging to find that the experimental values match well with the simulated values. We briefly discuss the effect of variation in the drift velocity on the performance parameters of the polarimeter. The implementation of this method in any future TPC polarimeter is also explored.

Design Studies of High-Resolution Readout Planes Using Zigzags With GEM Detectors

We have developed highly interleaved zigzag-shaped electrodes for collecting charge on the readout plane of various micropattern gaseous detectors (MPGDs), including gas electron multiplier (GEM) and micromega detectors. An optimized zigzag pad (or strip) anode can greatly enhance charge sharing among neighboring pads compared to traditional straight strip or rectangular pad designs and as a result can deliver excellent position resolution with minimal channel count, while exhibiting a virtually uniform response across the detector. We have systematically studied the effects of varying the parameters that define the zigzag geometry using simulations and have measured several printed circuit boards (PCBs) comprising a range of zigzag designs. Recently, we have employed laser ablation to generate zigzag patterns with pad-to-pad gaps smaller than 1 mil (or 25 μm). Reducing the gap well below the 3-mil limit imposed by traditional chemical etching has allowed the production of zigzag electrodes with unprecedentedly small feature sizes. In turn, laser-etched zigzag PCBs were shown to exhibit markedly improved performance over earlier generation PCBs, with position resolutions below 50 μm for a 2-mm pitch. This article will explore in detail the dependence of the position resolution on the structural parameters of a zigzag-shaped anode, specifically for the case of a quadruple GEM detector.