Gas Electron Multiplier Foils Research Articles

Construction of gas electron multiplier tracker for the J-PARC E16 experiment

The gas electron multiplier tracker (GTR) was developed and constructed for the J-PARC E16 experiment. The GTR is capable of operating in a high-counting environment of up to 5kHz/mm2. Additionally, its design is optimized to minimize the material budget and maximize acceptance. With high-quality Gas Electron Multiplier (GEM) foils, eight modules composed of 24 chambers were constructed. The gain of each chamber was measured to be over 6000, satisfying the experimental specification. This study provides a comprehensive description of the detector, including its design, assembly procedure, and construction process.

Production and validation of industrially produced large-sized GEM foils for the Phase-2 upgrade of the CMS muon spectrometer

The upgrade of the CMS detector for the high luminosity LHC (HL-LHC) will include gas electron multiplier (GEM) detectors in the end-cap muon spectrometer. Due to the limited supply of large area GEM detectors, the Korean CMS (KCMS) collaboration had formed a consortium with Mecaro Co., Ltd. to serve as a supplier of GEM foils with area of approximately 0.6m2. The consortium has developed a double-mask etching technique for production of these large-sized GEM foils. This article describes the production, quality control, and quality assessment (QA/QC) procedures and the mass production status for the GEM foils. Validation procedures indicate that the structure of the Korean foils are in the designed range. Detectors employing the Korean foils satisfy the requirements of the HL-LHC in terms of the effective gain, response uniformity, rate capability, discharge probability, and hardness against discharges. No aging phenomena were observed with a charge collection of 82mCcm−2. Mass production of KCMS GEM foils is currently in progress.

A Segmental 2D Readout Board Manufactured in Printed Circuit Board Technology for Gas Electron Multiplier Detectors.

The Gas Electron Multiplier (GEM) was introduced by Fabio Sauli in 1997. This technology is broadly used in current and planned High-Energy Physics (HEP) experiments. One of the key components of these detectors is a readout board, which collects charges amplified by GEM foils and transfers them to readout electronics. The commonly used Cartesian XY readout boards are manufactured from the same type of polyamide film used to produce the GEM foils. The manufacturing process utilizes a deep polyimide etching, similar to the Micro Chemical Vias (MCV) etching process, which is protected by patent. The material prepared in this way is glued onto a rigid substrate and mounted in a detector. The production process was developed at CERN, and the technology has been commercialized to a small extent. Consequently, only a few research centers have the ability to make dedicated readout strips readouts. GEM detectors are characterized by a segmented structure that allows the separation of an electron-multiplying structure from a readout. This feature enables the implementation of a new type of charge reading system without the need to interfere with the GEM foil system. A new approach is proposed to simplify production and reduce the costs of GEM detector readout boards. It is based on the concept of segmental readout structures that are manufactured in standard Printed Circuit Board (PCB) technology. The interconnectors and mountings are located on the back of the bottom, so it is possible to place the readout electronics behind the readout plate. The boards are designed in such a way that they can be panelized into a readout with a more extensive active area. The margin between PCBs is minimalized to approximately 200 µm, which is less than 1% of the 70 × 70 mm2 board area, so the active area is as big as possible. Therefore, this solution gives us the ability to further increase the size of a readout by adding additional segments, which reduces the cost of scaling up the detector size. A few research groups have suggested similar solutions that utilize PCB technology, but currently, only detectors with 1D zigzag readouts have been validated and used. The measurement results of other 2D (XY) redouts using PCB technology have not been presented. The measurements shown and discussed in this paper validated the proposed technology. X-ray radiographs were obtained, validating the ability to use this technology to manufacture readout boards for GEM detectors. In opposition to state-of-the-art readouts, the proposed solution can be manufactured by any PCB manufacturer without using MCV-patented technology. This gives the users flexibility in designing and ordering low-cost custom readouts.

GEM Parçacık Dedektörlerinde Lignoselülozik Malzeme Kullanım Potansiyeli

This study investigates the potential use of lignocellulosic material for Gas Electron Multiplier (GEM) foils in high-energy physics experiments. A 50 µm thick lignocellulosic film was created using a scattering method, and both surfaces were coated with a 2 µm thick copper electrode layer. Electrical characterization studies were conducted to assess the suitability of lignocellulosic material in GEM detectors. To ensure consistent atmospheric conditions during measurements, a special chamber was designed to monitor temperature and humidity values over time using an SHT3x sensor module and Rense Temperature/Humidity Meter. Electrical measurements were performed using a Keithley 4200 semiconductor characterization system, and I-V curves showing the current-voltage relationship under different atmospheric conditions were plotted. The results demonstrate the potential for developing sustainable and efficient detectors for various high-energy physics experiments using GEM detectors with lignocellulosic foils. This study comprehensively presents the advantages and disadvantages of using lignocellulosic material in GEM foils and contributes to the development of more environmentally friendly alternatives for GEM detector manufacturing.

Charging-up effect and uniformity study of a single mask triple GEM detector

The Gas Electron Multiplier (GEM) detector is one of the advanced members of the Micro Pattern Gas Detector (MPGD) family, used in High Energy Physics (HEP) experiments as a tracking device due to its high rate handling capability and good spatial resolution. The uniformity in the performance of the detector is an essential criterion for any tracking device.The presence of the dielectric medium (Kapton) inside the active volume of the GEM chamber changes its behaviour when exposed to external irradiation. This phenomenon is known as the charging-up effect. In this article, the charging-up effect over the entire surface of a Single Mask (SM) triple GEM chamber of dimension 10 cm × 10 cm is reported. The study of uniformity in terms of gain, energy resolution and count rate for the same chamber is also presented before and after the charging-up of the GEM foils.

Conceptual design of a GEM (gas electron multiplier) based gas Cherenkov detector for measurement of 17MeV gamma rays from T(D, γ)5He in magnetic confinement fusion plasmas.

The only method for assessing the fusion power throughput of a deuterium-tritium (DT) reactor presently relies on determining the absolute number of 14MeV neutrons produced in the DT plasma. An independent method, developed and investigated during the recent DT campaign at the Joint European Torus, is based on the absolute counting of 17MeV gamma rays produced by the competing T(D, γ)5He reaction that features a very weak branching ratio (about 3-6 × 10-6) when compared to the main T(D,n)4He reaction. The state-of-the-art spectrometer used for gamma-ray measurements in magnetic confinement fusion plasmas is LaBr3(Ce) scintillator detectors, although they require significant neutron shielding to extract a relatively weak gamma-ray signal from a much more abundant neutron field. A better approach relies on a gamma-ray detector that is intrinsically insensitive to neutrons. We have advanced the design of a gamma-ray counter based on the Cherenkov effect for gamma-rays whose energy exceeds 11MeV, optimized to work in the neutron-rich environment of a steady-state, magnetically confined fusion plasma device. The gamma-rays interact with an aluminum window and extract electrons that move into the radiator emitting photons via the Cherenkov effect. Since the Cherenkov light consists of few photons (25 on average) in the far UV band (100-200nm), a pre-amplifier is required to transport the photons to the neutron-shielded location, which may be a few meters away, where the readout elements of the detector, either a silicon or standard photomultiplier tube, are placed. The present work focuses on the development of a scintillating GEM (Gas Electron Multiplier) based pre-amplifier that acts as a Cherenkov photon pre-amplifier and wavelength shifter. This paper presents the result of a set of Garfield++ simulations developed to find the optimal GEM working parameters. A photon gain of 100 is obtained by biasing a single GEM foil to 1kV.

GEM foil characterization in cost-effective, and efficient way and attempt made to use it as an imaging detector

Increasing demand for security scanners and medical imaging techniques has risen with the advancement of technology based on silicon sensors. However, these technologies are much expensive and require critical handling. The Gas Electron Multiplier (GEM) foil, based detector has been attempted to use as an imaging detector. GEM foil is generally constructed using 50 μm highly insulating film coated with 5 μm copper on both sides and a network of highly dense double conical holes of size 50-70 μm in it. Due to the microscopic structure of holes and the dependence of the electric field inside them, it becomes essential to study the defects and uniformity of holes along with the electrical property of foils in various conditions. In our work, we have tested GEM foils both optically and electrically and saw the response of the triple-layered GEM detector towards fake signal and gain.

Development of a Segmented GEM Readout detector

Micromegas (Micro-MEsh GAseous Structures) detectors are a type of micro-pattern gaseous detectors. The primary charges are amplified in electron avalanches between a planar anode and a mesh typically 120 μm above the anode. For resistive anode type Micromegas detectors the signal is read out via copper readout strip layers below the anode. A 2D particle position can be reconstructed using two perpendicular readout strip layers below the resistive anode structure.Using a standard 2D resistive anode Micromegas readout structure, a unique 2D particle position reconstruction is only possible if the detector is hit by only one particle at the same time. Ambiguities will occur if multiple particles arrive at the same time. A unique X–Y assignment is strongly complicated.This issue can be resolved by replacing the mesh with a GEM (Gas Electron Multiplier) foil, which is segmented into 0.5 mm wide strips on at least one of the two sides. The GEM strips need to be turned by 45∘ with respect to the Micromegas readout strips. Thus the detector with a GEM foil segmented on both sides has four readout strip directions (X, Y, U and V) and a detector with a GEM foil segmented on only one side has three readout strip directions (X, Y and V).A prototype of such a Segmented GEM Readout (SGR) detector is built with GEM strips and readout strips perpendicular to each other. Test beam measurements with this detector were performed using 120 GeV muons. Results of the test beam measurements are presented here.

Visual investigation of possible degradation in GEM foil under test

Visual investigation of a single mask Gas Electron Multiplier (GEM) foil, showing small resistance (∼ 40 kΩ), is performed manually using an optical microscope. The GEM foil is scanned and the different imperfections in the foil are identified. Different techniques are used to clean the GEM foil to remove the short paths created between the GEM electrodes. The details of the method used for cleaning the GEM foil and the result of leakage current measurement after the cleaning of the foil are discussed in this article.

Present outcome from the NUMEN R&D phase

The NUMEN experiment aims at measuring double charge exchange reaction cross sections using heavy-ion beams of unprecedented intensity on specific isotopes. In order to get data-sets with good statistical significance from challengingly low cross sections it asks for the upgrade of the pre-existing magnetic spectrometer MAGNEX at INFN-LNS, in Catania. These reactions prove to be a way of getting information on the nuclear matrix elements of the neutrino-less double beta decay, the most promising probe to establish the Majorana or Dirac nature of the neutrino, and to evaluate the effective neutrino mass. A new setup for the target system is under development and adequate detectors are under study for the tracking and the identification of heavy ions at the expected rate up to 5 Mpps and for gamma-ray measurements. The tracker is a time projection chamber with electron amplification based on a triple Thick Gas Electron Multiplier (THGEM) foil, the particle identification is performed with telescopes composed of Silicon Carbide (SiC) and Thallium doped Cesium Iodide (CsI(Tl)) sensors, the gamma-ray detection is sustained with Cerium doped Lantanum Bromide (LaBr3(Ce)) scintillator detectors. Here a selection of results of the R&D phase and the integration study are presented.

Manufacturing of a 70 × 70 mm2 LTCC strip electrode readout for Gas Electron Multiplier detectors

Introduced by Fabio Sauli in 1997, the Gas Electron Multiplier (GEM) technology is commonly used in many high energy physics experiments. It has proven unique value in many scientific domains and adaptability to new research tasks. Typically, the GEM detectors are made with polyimide films (GEM foils and readout plate), halogen-free FR4 epoxy resins (supporting and stretching structures), conductive copper layers, etc. Because of outgassing and ageing, those components release in time residues of dust, moisture, and vapors. The residues pollute the gas mixture and consequently degrade the detector's working parameters. To avoid such a problem, devices can be constantly flushed by pure gas from an external source. This solution is not optimal for autonomous space detectors because of volume and weight limitations. The paper describes the successive work to develop an autonomous GEM detector without a gas mixture circulation system. As a solution, the use of Low-Temperature Cofired Ceramics (LTCC) materials was proposed and validated. The dedicated LTCC readout plates were manufactured and tested, and results are presented.

The qualification of GEM detector and its application to imaging

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 μm highly insulating foil (Kapton/Apical) coated with 5 μm 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 gained a right to use CERN developed technology in order to produce commercially viable GEM foils. Micropack Pvt. Ltd. is another company in India which has successfully manufactured good quality GEM foils. Due to the microscopic structure of holes and dependence on the electric field inside, it becomes essential to study the defect and uniformity of holes along with the electrical property of foils under ambient conditions. In this work we are reporting the tests condition of Techtra GEM foils. We report on the development of a cost effective and efficient technique to study the GEM foils holes geometry, distribution, and defects. We also report on the electrical properties of these foils like leakage current, stability, and discharges. At the detector level, we describe the high voltage (HV) response, gain, uniformity, and stability. The GEMs have been proposed to have a wider applications, so we performed a feasibility study to utilize these for the imaging. We irrediated various objects of varying density with X-rays and reconstructed the images. The reconstructed image shows a good distinction between materials of different densities, which can be very useful in various applications like medical imaging or cargo imaging.

Effect of hole geometry on charge sharing and other parameters in GEM-based detectors

Gas Electron Multipliers (GEM) are among the more prominent Micro-Pattern Gaseous Detectors (MPGDs) and widely used in high energy particle physics experiments and various related applications. Adoption of different production techniques lead to holes of varying geometries in GEM foils. Since the response of a GEM-based detector is closely related to the hole geometry through the influence of the latter on charge sharing and transport through GEM foils, attempts have been made to relate hole configurations to different figures of merit of a detector.Numerical simulations have been performed to study the effects of hole geometry on important parameters such as charge sharing, collection efficiency, extraction efficiency, gain, possibility of transition from avalanche to streamer modes for single-, double- and triple-layer GEM detectors. The numerical estimates have been compared to available experimental data. The comparisons, although not always in agreement, are found to be generally encouraging.

Impact of the hole orientation of asymmetric GEM foils on the performance of single and triple GEM detectors

The Gas Electron Multiplier (GEM) foil is an amplification stage that has been introduced to overcome the problem of discharges observed in gaseous detectors. There are two major production techniques of GEM foils: double-mask and single-mask etching. Despite being an effective method, an asymmetry is observed between the top and bottom diameters of GEM holes in single mask technique compared to double mask one. In this paper we describe extensive simulations and measurements to study this hole asymmetry and its effect on the performance of GEM based detectors. The experimental data is collected using GEM foils of various hole geometries and orientations. In simulations, the same dimensions are used to study the properties of the detector. Simulations are performed with the Garfield++ simulation package along with ANSYS for creating the geometry of the GEM foils as well as the triple-GEM detector and the meshing needed for the field calculations. The simulation results match the observations from experimental studies. The gains measured with single and triple-GEM detectors are lower if asymmetric foils are oriented with the smaller diameters towards the readout plane. Detailed simulation of the amplification and collection steps indicates that the lower gain is attributed to a loss of electrons at the GEM3 foil for the first time.

FIRE: A compact nanodosimeter detector based on ion amplification in gas

One goal of nanodosimetry is to determine statistical quantities of ionization distributions in nanometric volumes. It is hypothesized here that these quantities are related to the initial biological damages in DNA from ionizations. Thus nanodosimetric quantities will potentially complement or replace the concept of RBE-weighted absorbed dose and hence they could be applied in treatment planning systems, risk assessments for radiation protection and space radiation. The development of a compact and portable nanodosimeter detector available for clinical routine is a significant step towards that goal. We present extensive measurements to characterize the performance of the FIRE (Frequency of Ion REgistration) nanodosimeter detector. It operates on similar principles like the Gas Electron Multiplier (GEM). Contrary to GEMs the FIRE detector registers positive ions instead of electrons and operates at low pressures of 0.5 Torr to 2.5 Torr. In addition, the FIRE nanodosimeter capitalizes on the usage of a resistive cathode in order to suppress discharges. Moreover, the geometry of the FIRE detector is adapted to the low pressure by enlarging the typical dimensions of a GEM foil by two orders of magnitude.The authors present two configurations of the compact FIRE nanodosimetry detector. The resistivities of the two configurations differ by six orders of magnitude. The lower resistivity should allow for faster removal of the charges attached to the wall inside the hole channel. Measurements of mean number of ions produced by 5MeV alpha particles in low pressure propane gas, mean number of dark counts, the ion arrival time, and the mean avalanche charge are presented. The dependency of these parameters on acceleration voltage, drift voltage, pressure and hole diameter were investigated.

Electrical discharge propagation between GEM foils

This paper presents the studies of fast sequential discharge formations in neighboring Gas Electron Multiplier foils (so called fast discharge propagations). We report on the characteristics of the time delay between the discharges, which has been shown to be of the order of tens of nanoseconds. This time delay decreases both with increasing voltage on the foil where the secondary discharge occurs as well as with decreasing distance between the neighboring foils. Optical measurements of the discharges in two- and three-stage detector setups show that the propagating discharge does not occur directly below the primary discharge, but is displaced from the shortest line between neighboring foils. This observation, together with Scanning Electron Microscope and Energy Dispersive Spectroscopy analyses of the material deposited below the position of the primary discharge provide valuable information on the time evolution of the fast discharge propagation through the detector and its formation mechanism. In the light of these findings, we propose and discuss a new hypothesis for the occurrence of the secondary discharges.

A study of asymmetric tensile properties of large area GEM foil

Gas Electron Multiplier (GEM) technology is being used in various applications, particularly in high energy physics experiments. The GEM is known as a reliable detector in high radiation environment which can maintain high temporal and position resolution. GEM foil is the basic part of the detector which consists of a composite material (polyimide and copper). Large size GEM foil has complex mechanical structure and asymmetries which mainly arises due to formation of the HV sectors in the foil. These asymmetries become very relevant when large size foils are stretched to build a detector. In this article asymmetry affects are presented that define the tensile properties of a large size segmented GEM foil.

Neutron Detection Using a Gadolinium-Cathode Gas Electron Multiplier Detector

A gas electron multiplier (GEM) detector with a gadolinium cathode has been developed to explore its potential application as a neutron detector. It consists of three standard-sized ($10\times 10$ cm${}^{2}$) GEM foils and a thin gadolinium plate as the cathode, which is used as a neutron converter. The neutron detection efficiencies were measured for two different cathode setups and for two different drift gaps. The thermal neutron source at the Korea Research Institute of Standards and Science (KRISS) was used to measure the neutron detection efficiency. Based on the neutron flux measured by KRISS, the neutron detection efficiency of our gadolinium GEM detector was $4.630 \pm 0.034(stat.) \pm 0.279(syst.) \%$.

Influence of hole geometry on gas gain in GEM detectors

Gas electron multipliers (GEMs) belong to the most modern and advanced technologies in the field of gaseous detectors. Detectors, based on the GEM technology, enjoy great popularity in various fields of physics. Especially in the field of high-energy physics, GEMs are well-appreciated thanks to their flexibility in geometry, resistance to aging and excellent performance in high-rate environments. The core of the detector consists of thin foils with an etched pattern of holes. The detection principle relies on electron multiplication inside the holes, where a high electric field is present. New etching techniques have been used for the production of large-size (0.3 m2 - 0.4 m2) GEM foils needed for high-energy physics experiments. The new techniques result in different hole geometries. To better understand the gas gain dependence on the hole geometry, several measurements have been performed with a triple-GEM detector, and have been complemented by GARFIELD++ simulations. The results are compared with other recent studies.

Investigation of Copper-Less Gas Electron Multiplier Detectors Responses to Soft X-rays.

In this paper, we report on the systematic study of different variants of X-ray detectors based on Gas Electron Multiplier (GEM) technology using modified GEM foils with greatly reduced amount of copper. The main goal of this study was understanding the performance of such detectors applied in X-Ray Fluorescence (XRF) elemental analysis. Reduction of the amount of copper in the detector structure is crucial for suppression of XRF background from copper, but one has to ensure that key detector parameters are not affected by such modification. The tested detector variants include detectors with different types of copper-less GEM foils, which have been manufactured starting from standard copper-clad foils and removing partially the copper layer in additional post-processing steps. The results are analyzed and discussed with a particular focus on the energy resolution, uniformity of gas gain and energy resolution across the detector area, and on the long-term stability of the gas gain. Long-term stability tests performed for selected detectors do not indicate for any accelerated aging of the copper-less detectors compared to standard detectors using copper-clad GEM foils. The presented results lead us to conclude that the copper-less GEM detectors are promising devices to suppress the XRF background.