Gas Electron Multiplier Technology Research Articles

Development of a Triple-GEM detector with strip readout and GEMINI chip for X rays and neutron imaging

Thermal neutron imaging can be a useful tool in the study of the internal structure of an object. The different attenuation properties of the materials with respect to X rays give rise to different interactions and the result is a complementary non-destructive analysis, which can provide important additional information. This technique has been successfully employed in different areas of work, especially in material science and cultural heritage studies. This paper describes the development of a new detection system and its characterization performed with X ray emissions. The system features the use of a gaseous detector, based on the Gas Electron Multiplier technology, and a fully digital electronic readout, with a combination of custom-made ASICs (called GEMINI) and FPGA boards, enabling fast single photon counting. The detector can be thus used directly for X ray imaging, while the addition of a suitable converter in its active volume will allow for detection of neutrons and for reconstruction of their tracks. The readout system is based on a x-y strip structure and features the reconstruction of single events through the center of mass methodology, allowing for accurate tomography, with sub-mm spatial resolution, in combination with sub-ms time resolution and high rate capabilities (up to MHz/mm2).

Analysis of discharge events in the CMS GE1/1 GEMdetectors in presence of LHC beam

In July 2022, the experiments installed on the Large Hadron Collider (LHC) accelerator ring started a new data taking phase, Run-3. Before this period, an upgrade campaign took place during the so called Long Shutdown 2 (2018–2022). In particular, the muon system of the CMS experiment has been upgraded with the installation of a new gas detector station, GE1/1, based on Gas Electron Multiplier technology (GEM). The CMS experiment has scheduled the installation of two additional GEM stations: GE2/1 and ME0. The aim of the GEM stations is to maintain the performance of the muon system, reached during the last data taking phase (Run-2), with the increase of instantaneous luminosity expected at the LHC. The installed GE1/1 station covers the pseudorapidity region 1.55 <|η|< 2.18. GE1/1 participated in the CMS Run-3 data taking from July to November 2022 and, in this period, its detectors were exposed for the first time to the radiation produced during the collisions of the LHC beams, with a center of mass energy of 13.6 TeV. Since the first days of Run-3, where only a few bunches collided in CMS, the GE1/1 detectors started to experience a significant number of discharges, affecting their smooth operation during the data taking. In this talk, we present an analysis of discharges, which started by simply counting the number of discharges occurring per detector. An interesting phenomenon observed was that the discharge rate can vary a lot among the installed detectors; this is due to the fact that the occurrence of discharges is driven by the manufacturing of the GEM foils used in the detectors. Imperfections in their manufacturing can lead to large variation in the discharge rate. In addition, the rate can vary in time, due to the fact that discharges can produce damage at the site generating them, deactivating a particular hole or, in the worst case, producing a short circuit in the GEM foil, deactivating a part of the foil amplification region. We present the evolution of the discharge rate in time and its dependence on the HV working point and on the luminosity delivered by the LHC beams. This contribution illustrates the actions taken to mitigate the discharge rate and to assure a smooth detector operation.

Construction and test of a transition-radiation detector prototype based on thick gas electron multiplier technology

A transition-radiation detector (TRD) is a powerful device for highly relativistic electron (γ ≳ 1,000) identification. Electron identification is crucial for tagging the outgoing scattered electrons in an electron-ion collider (EIC) detector. Employing a TRD at the electron forward region of an EIC detector can provide the necessary electron identification with high hadron rejection over a wide momentum range. Thick gas electron multiplier (THGEM) technology is suitable for radiation detection in modern high-energy experiments owing to its high-granularity structure, radiation hardness, high-rate capability and ease of large-area production. This study investigates a TRD prototype based on THGEM technology through soft X-ray and electron beam experiments. Geant4 simulation were extensively exploited to understand the operation of TRD prototype with different gas mixtures. Particularly, the performance of TRD prototype with an electron beam at the DESY, with argon-based gas rather than xenon-based gas, agreed well with the simulation analyses in all important aspects. Based on the consistency of the experimental and simulation results, a likelihood analysis on the simulated total energy deposit in the xenon-based working gas would suggest a pion rejection improvement with the optimization of detector design, readout electronics and identification algorithm.

GEM Detectors for the Upgrade of the CMS Muon Spectrometer

The Large Hadron Collider (LHC) will be upgraded in several phases to allow a significant expansion of its physics program. We are nearing the end of Long Shutdown 2 (LS2, 2019-2021), after which the LHC will initiate its third running period (Run-3) expected to last three years. In Run-3 LHC will collide protons with an instantaneous luminosity of 2-3×1034cm−2s−1 exceeding its design luminosity by a factor of 2-3, allowing the CMS experiment to collect an integrated luminosity of approximately 100 fb−1/year. A subsequent upgrade in 2025-27 (Long Shutdown 3 - LS3) will increase the luminosity up to 5×1034cm−2s−1. The CMS muon system must enable a physics program that maintains sensitivity for electroweak measurements and for Beyond the Standard Model searches, similar to what was achieved in Run-1 and Run-2. To cope with the corresponding increase in trigger rates and to provide additional coordinate measurements in the high background environment, the installation of additional sets of muon detectors, referred to as GE1/1, GE2/1 and ME0, that use Gas Electron Multiplier (GEM) technology, has been approved. The GE1/1 chambers have already been installed in spring-summer 2020 and are currently being commissioned and tested with cosmic rays. The construction of GE2/1 will start in 2021, while for ME0 the final R&D is in progress and construction is foreseen in 2023. We present an overview of the Muon Spectrometer upgrade using the GEM technology, the performance of the GE1/1 chambers during Quality Control tests and in cosmic ray tests, and the design of the GE2/1 and ME0 chambers.

Quality control of mass-produced GEM detectors for the CMS GE1/1 muon upgrade

The series of upgrades to the Large Hadron Collider, culminating in the High Luminosity Large Hadron Collider, will enable a significant expansion of the physics program of the CMS experiment. However, the accelerator upgrades will also make the experimental conditions more challenging, with implications for detector operations, triggering, and data analysis. The luminosity of the proton–proton collisions is expected to exceed 2–3×1034 cm−2s−1 for Run 3 (starting in 2022), and it will be at least 5×1034 cm−2s−1 when the High Luminosity Large Hadron Collider is completed for Run 4. These conditions will affect muon triggering, identification, and measurement, which are critical capabilities of the experiment. To address these challenges, additional muon detectors are being installed in the CMS endcaps, based on Gas Electron Multiplier technology. For this purpose, 161 large triple-Gas Electron Multiplier detectors have been constructed and tested. Installation of these devices began in 2019 with the GE1/1 station and will be followed by two additional stations, GE2/1 and ME0, to be installed in 2023 and 2026, respectively. The assembly and quality control of the GE1/1 detectors were distributed across several production sites around the world. We motivate and discuss the quality control procedures that were developed to standardize the performance of the detectors, and we present the final results of the production. Out of 161 detectors produced, 156 detectors passed all tests, and 144 detectors are now installed in the CMS experiment. The various visual inspections, gas tightness tests, intrinsic noise rate characterizations, and effective gas gain and response uniformity tests allowed the project to achieve this high success rate.

Upgrade of the CMS Muon Spectrometer in the forward region with the GEM technology

The Large Hadron Collider (LHC) will be upgraded in several phases that will allow significant expansion of its physics program. The final luminosity of the accelerator is expected to exceed 5 × 1034 cm−2 s−1, five times more than the original design value. The CMS muon system must be able to sustain a physics program after the increase of luminosity and maintain a sensitivity to electroweak physics and to TeV scale searches similar to what was achieved up to now. To cope with the corresponding increase in background rates and trigger requirements, the installation of additional sets of muon detectors based on Gas Electron Multiplier (GEM) technology, referred to as GE1/1, GE2/1 and ME0, has been planned. The installation and commissioning of the GE1/1 chambers is scheduled by 2019/20, while the GE2/1 and ME0 detectors are expected to be installed between 2023 and 2027. We present an overview of the Muon Spectrometer upgrade using the GEM technology, a description of the ongoing GE1/1 project, the production, qualification and chambers installation as well as the details of the GE2/1 and ME0 upgrades. For the latter projects, we will focus on the ongoing R&D and proposed novel solutions for the detector and electronics.

CMS phase-II upgrade with GEM detector

The Large Hadron Collider (LHC) will be upgraded in several phases that will allow significant expansion of its physics program. The final luminosity of the accelerator is expected to exceed 5 × 1034cm−2s−1, five times more than the original design value. The CMS muon system must be able to sustain a physics program after the increase of luminosity and maintain sensitivity for electroweak physics for TeV scale searches similar to what was achieved up to now. To cope with the corresponding increase in background rates and trigger requirements, the installation of additional sets of muon detectors based on Gas Electron Multiplier (GEM) technology, referred to as GE2/1 and ME0, has been planned. The installation and commissioning of the GE2/1 chambers is scheduled in 2022, and for ME0 detectors are expected to be installed between 2022 to 2024. We present an overview of the Muon Spectrometer upgrade using GEM technology, a detailed description of the GE2/1 and ME0 upgrade in terms of design, pre-production chambers, mechanics, installation services etc. We will focus in particular on the novel solutions adopted for realization of the latter project, with a summary of the ongoing R&D activities

Characterization and first field results of a new 64ch custom front-end ASIC for GEM readout

Abstract For the readout of the upgraded inner tracker of the BESIII experiment based on a innovative lightweight Cylindrical Gas Electron Multiplier technology a custom readout electronics is being developed. The special feature of this new front-end is the ability to perform an analog charge measurement in parallel to the event time stamp, operating in a constrained power envelop within a superconductive solenoid. The core of the new front-end is a custom designed 64ch ASIC featuring a fully digital output and operated in triggerless mode. Sustained rate per channel is up to 60 kHz. The TDCs time resolution is better than 100 ps. The energy measurement can be obtained from a time-over-threshold (ToT) measurement or by a 10-bit digitization of the peak amplitude by a sample and hold circuit (S/H).

Characterization of three GEM chambers for the SBS front tracker at JLab Hall A

ABSTRACTA new Large-Acceptance Forward Angle Spectrometer [Super Bigbite Spectrometer (SBS)], is under development for the upcoming experiments in Hall A at the Thomas Jefferson National Accelerator Facility (Virginia, USA), where a longitudinally polarized (up to ) electron beam up to 12 GeV energy is now available. The excellent beam intensity (up to 100 A), combined with innovative polarized targets, will provide luminosity up to , opening interesting opportunities to investigate unexplored aspects of the inner structure of the nucleons. In one of the most demanding configuration, the new spectrometer will consist of a dipole magnet, one front charged particle tracker, two identical proton polarimeters with related back trackers and a segmented hadron calorimeter.The front tracker, placed just after the dipole magnet, consists of up to six layers of large area GEM (Gas Electron Multiplier) chambers (); each chamber is made by three adjacent GEM modules of active rectangular area (18 modules as a total).We have chosen the GEM technology in order to optimize spatial resolution (∼80 mm), high hit rate (), cost/performance and high radiation hardness.We present the main features of the SBS front tracker and its GEM detectors and, finally, we discuss the ongoing tracker commissioning at JLab and show some representative test results.

Particle identification studies with a full-size 4-GEM prototype for the ALICE TPC upgrade

A large Time Projection Chamber is the main device for tracking and charged-particle identification in the ALICE experiment at the CERN LHC. After the second long shutdown in 2019/20, the LHC will deliver Pb beams colliding at an interaction rate of about 50 kHz, which is about a factor of 50 above the present readout rate of the TPC. This will result in a significant improvement on the sensitivity to rare probes that are considered key observables to characterize the QCD matter created in such collisions. In order to make full use of this luminosity, the currently used gated Multi-Wire Proportional Chambers will be replaced. The upgrade relies on continuously operated readout detectors employing Gas Electron Multiplier technology to retain the performance in terms of particle identification via the measurement of the specific energy loss by ionization dE/dx. A full-size readout chamber prototype was assembled in 2014 featuring a stack of four GEM foils as an amplification stage. The performance of the prototype was evaluated in a test beam campaign at the CERN PS. The dE/dx resolution complies with both the performance of the currently operated MWPC-based readout chambers and the challenging requirements of the ALICE TPC upgrade program. Detailed simulations of the readout system are able to reproduce the data.

GEM tracker for high-luminosity experiments at the JLab Hall A

ABSTRACTA Large-Acceptance Forward Angle Spectrometer (Super BigBite) is under development for the upcoming experiments in Hall A at Jefferson Lab to optimally exploit the exciting opportunities offered by the 12 GeV upgrade of the electron beam. The tracking of this new apparatus is based on the Gas Electron Multiplier technology, which has been chosen to optimize cost/performance, position resolution and meet the high hits rate (>1 MHz/cm2). In this report we present the technical features of the detector and comment on the presently achieved performance.

A micro-pattern gaseous detector for beam monitoring in ion-therapy

A micro-pattern gaseous detector based on gas electron multiplier technology (GEM detector) was developed as a new transmission beam monitor for charged-particle therapy to obtain real-time information about the parameters of a therapeutic beam. Feasibility tests for the GEM detector were performed using an 80-MeV proton beam to evaluate the lateral intensity distributions of a pencil beam and the dose delivered to a target. The beam intensity distributions measured with the GEM detector were in good agreement with those measured with an imaging plate while the charge output from the GEM detector was in proportion to that of a reference dose monitor of an ionization chamber design. These experimental results showed that the GEM detector can be used not only as a beam monitor for the position and two-dimensional intensity distribution but also as a dose monitor. Thus, it is possible to simultaneously measure these beam parameters for beam control in charged-particle therapy using a single GEM-based transmission monitor.

Upgrades of the ALICE TPC Front-End Electronics for Long Shutdown 1 and 2

This paper presents the front-end electronics upgrades of the ALICE Time Projection Chamber detector for the coming years, with a focus on the upgrades for Long Shutdown 2. The Large Hadron Collider is currently in Long Shutdown 1 following a successful first run, and upgrades of the detectors are underway to support the higher particle interaction rates planned for the next run. For the Time Projection Chamber, the increase in data due to the higher interaction rate and higher energy will cause a bottleneck in the Readout Control Unit and a new board is in development which increases the data-link speed to the back-end. Another more general upgrade of the ALICE experiment is planned for Long Shutdown 2, foreseen to start in 2018. In this case the goal is to cope with an even higher interaction rate of 50 kHz for Pb–Pb collisions. The present Multi Wire Proportional Chambers of the Time Projection Chamber will then be replaced by Gas Electron Multiplier technology. At the same time, the front-end electronics and readout system will also be replaced.

Characterization of a thermal neutron beam monitor based on gas electron multiplier technology

Research into valid alternatives to |$^{3}$|He detectors is fundamental to the affordability of new neutron spallation sources like the European Spallation Source (ESS). In the case of ESS it is also essential to develop high-rate detectors that can fully exploit the increase of neutron flux relative to present neutron sources. One of the technologies fulfilling these requirements is the gas electron multiplier (GEM), since it can combine a high rate capability (MHz|$/$|mm|$^{2}$|⁠), a coverage area up to 1 m|$^{2}$| and a space resolution better than 0.5 mm. Its use as a neutron detector requires conversion of neutrons into charged particles. This paper describes the realization and characterization of a thermal neutron GEM-based beam monitor equipped with a cathode containing |$^{10}$|B for neutron conversion. This device is constituted by a triple GEM detector whose cathode is made of an aluminum sheet covered by a 1 |$\mu $|m thick |$^{\hbox{nat}}$|B|$_{4}$|C layer. The method used to realize a long-lasting |$^{{\mathrm {nat}}}$|B|$_{4}$|C layer is described and the properties of such a layer have been determined. The detector performances (measured on the ISIS-VESUVIO beam line) in terms of beam profile reconstruction, imaging, and measurement of the thermal neutron beam energy spectrum are compatible with those obtained by standard beam monitors.

Optimization of the gas flow in a GEM chamber and development of the GEM foil stretcher

The gas electron multiplier technology has been proven to tolerate rat e larger than 50 MHz/cm2 without noticeable aging and to provide sub resolution on working chambers up to 45 cm x 45 cm. A new gas electron multiplier-based tracker is under development for the Hall A upgrade at Jefferson Lab. The chambers of the tracker have been designed in a modular way: each chamber consists of 3 adjacent gas electron multiplier modules, with an active area of 40 cm x 50 cm each. We optimized the gas flow inside the gas electron multiplier module volume, using the COMSOL physics simulator framework; the COMSOL-based analysis includes the design of the inlet and outlet pipes and the maximization of the uniformity of the gas flow. We have defined the procedures for the assembling of the gas electron multiplier modules and designed a mechanical system (TENDIGEM) that will be used to stretch the GEM foils at the proper tension (few kg/cm); the TENDIGEM is based on the original design developed at LNF.

Test of the GEM front tracker for the SBS spectrometer at Jefferson lab

A new Large-Acceptance Forward Angle Spectrometer (Super BigBite) is under development at JLab/Hall A to optimally exploit the exciting opportunities offered by the 12 GeV upgrade of the electron beam. The tracking of this new apparatus is based on the gas electron multiplier technology, which has been chosen to optimize cost/performance, position resolution and meet the high hits rate (&gt;1 MHz/cm2). The first gas electron multiplier detector prototypes were designed, built and tested at the DESY test beam facility in Hamburg, by using an electron beam with energy from 2.0 to 6.0 GeV. In particular, two gas electron multiplier chambers (10 x 10 cm2 and 40 x 50 cm2, respectively) were equipped with a new implementation of the APV25 readout chip. Measurements were performed at different impact points and angles between the electron beam and the plane of the gas electron multiplier chambers. In this report we present the technical characteristics of the detector and comment on the presently achieved performance.

A new 3He-free thermal neutrons detector concept based on the GEM technology

A thermal neutron detector based on the Gas Electron Multiplier technology is presented. It is configured to let a neutron beam interact with a series of borated glass layers placed in sequence along the neutron path inside the device. The detector has been tested on beam both at the ISIS (UK) spallation neutron source and at the TRIGA reactor of ENEA, at the Casaccia Research Center, near Rome in Italy. For a complete characterization and description of the physical mechanism underlying the detector operation, several Monte Carlo simulations were performed using both Fluka and Geant4 code. These simulations are intended to help in seeking the optimal geometrical set-up and material thickness (converter layer, gas gap, sheet substrate) to improve the final detector design in terms of achieving the best detector efficiency possible.

The LHCb muon detector commissioning and first running scenarios

The LHCb muon detector, part of the first LHCb trigger level (L0), has been built to provide a fast and efficient identification of the muons produced in pp collisions at the LHC. The expected performances are: 95% L0 trigger efficiency within a 25 ns time window and muon identification in L0 with a p T resolution of 20%. The detector has been built using Multi-Wire Proportional Chambers and Gas Electron Multiplier technology. The chambers are arranged in five stations, interspersed with iron filters placed along the beam pipe. The results obtained in the commissioning of all the installed chambers and the measured performances are presented. The strategies foreseen for the detector calibration, the results of the space and time alignment efforts and few first running scenarios are discussed.

Development studies for the ILC: Measurements and simulations for a time projection chamber with GEM technology

A Time Projection Chamber (TPC) with Gas Electron Multiplier (GEM) technology is well suited for usage as central tracker at the International Linear Collider (ILC). To study the high potential of this detector type a small prototype of 25 cm length was built in Karlsruhe and used in several experimental setups. In this publication the results of these measurements and of additional Monte Carlo simulations are presented. By introducing the so-called equivalent drift distance a combination of all results was possible leading to a recommended configuration of the multi-GEM tower for the ILC–TPC. It will be shown that for conditions considered in the TESLA–TDR the transverse spatial resolution will be able to reach 65 μ m for 10 cm and 190 μ m for 200 cm drift at the ILC. This as well as the expectations for longitudinal spatial resolution, for energy resolutions of the specific ionization, and for single pad row efficiency should be able to meet the requirements of a future ILC–TPC.