Electron Multiplier Research Articles

Development of a Bragg-edge Neutron Transmission Imaging Detector Combined with Micro-structured Boron Cathode and Glass Gas Electron Multiplier

Development of a Bragg-edge Neutron Transmission Imaging Detector Combined with Micro-structured Boron Cathode and Glass Gas Electron Multiplier

Development of a water-based cooling system for the Muon Chamber detector system of the CBM experiment

A water-based cooling system is being investigated to meet the cooling requirement of the Gas Electron Multiplier (GEM) based Muon Chamber (MuCh) detector system of the Compressed Baryonic Matter (CBM) experiment at GSI, Germany. The system is based on circulating cold water through the channels inside an aluminium plate. The aluminium plate is attached to a GEM chamber. A feasibility study is conducted on one small and two real-size prototype cooling plates. A microcontroller-based unit has been built and integrated into the system to achieve automatic control and monitoring of temperature on the plate surface. The real-size prototypes have been used in a test beam experiment at the CERN SPS (Super Proton Synchrotron) with the lead beam on a lead target. A setup using three prototype modules has been prepared in the lab for testing in a simulated real-life environment. This paper discusses the working principle, mechanical design, fabrication, and test results of the cooling prototypes in detail.

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.

Secondary electron emission characteristics of alumina coating on metallic substrate prepared by atomic layer deposition

The main objective of this study is to research the secondary electron emission characteristic of different thickness alumina coatings which are prepared by atomic layer deposition (ALD) technique on several metallic secondary-emitting materials. The experimental results reveal that secondary electron yield (SEY) property concerned with the metal work function and the surface topography of alumina coatings when coating thickness is in the nanometer level. In addition, after utilizing SEY measurement setup and pulsed electron gun, the SEY curves of metallic substrates with different thickness alumina coatings and primary energy (PE) of incident electron could be measured. From an analysis of the SEY curves, some key parameters related to secondary electron emission characteristics such as the maximum SEY value and its corresponding PE of incident electron, and the penetration depth of incident electron can be obtained. Furthermore, basing on the ALD technique and on the SEY results of stainless steel substrate coated with 80-cycle alumina thin film, a novel 18-stage discrete dynode electron multiplier (DDEM) was fabricated and tested. The gain of DDEM 1.6× 106 was obtained.

Performance of a resistive micro-well detector with capacitive-sharing strip anode readout

The present study is carried out to demonstrate a new type of high-performance readout structure with low readout channel count developed for large-area micro pattern gaseous detectors. The structure exploits capacitive coupling between a vertical stack of 5 μ m thick copper pad layers sandwiched between 50 μ m thick polyimide foils to simultaneously transfer and spread the avalanche charges from the gaseous detector’s amplification structure to several strips or pads in the anode readout plane. The unique feature of the lateral spread of the avalanche charge size on several readout strips or pads is possible owing to well-defined configuration and sizes of the pads in layers of the vertical stack. This is known as a “capacitive-sharing” readout structure and this opens the door for high spatial resolution performance with low readout channel counts for large-area Micro Pattern Gaseous Detectors. Capacitive-sharing readout structures are fabricated using standard printed circuits boards manufacturing process. The concept is highly versatile as it can easily be implemented in any type of Micro Pattern Gaseous Detector’s amplification structure (Gas Electron Multipliers, micro-mesh gaseous structures, resistive micro-well detectors) and with a wide range of readout patterns (pads, strips, zigzags etc.). The technology also has a high degree of flexibility in terms of readout segmentation (pads or strip) pitch, with minimum impact on spatial resolution performances. The present study provides a detailed description of the capacitive-sharing readout concept and discusses a small resistive micro-well detectors prototype assembled with a two-dimensional capacitive-sharing strip readout structure as a proof of concept and with strip pitch of 800 μ m in both X and Y direction. The prototype was characterized in electron beam in the Hall D Beam Test setup at Jefferson Lab and a spatial resolution of (60 ± 1) μ m was achieved for both X and Y strips with an efficiency of (98.0 ± 0.9) % at the plateau and a signal arrival time jitter between neighboring strips less (6.00 ± 0.04) ns. Finally, we explore new ideas to expand the concept of capacitive-sharing readout structures to large particle detectors for future large scale particle physics experiments.

Electronics for the far-forward CMS muon detector upgrade, ME0

With the High Luminosity upgrade of the Large Hadron Collider (LHC) we expect increased instantaneous luminosities up to 7.5 × 1034 cm−2 s−1, or five times more than the original values. In order to maintain performance of the Compact Muon Solenoid (CMS) experiment under these conditions, ME0 is one of three new muon sub-detectors being added, along with GE1/1 and GE2/1, which use the triple Gas Electron Multiplier (GEM) technology. ME0 is designed to cover the forward region of 2.0 < |η| < 2.8, thus improving muon reconstruction at high background rates by supplementing other overlapping muon subsystems up to |η| = 2.4, while also extending the acceptance for the first time to |η| = 2.8. The readout electronics for ME0 must be designed to accommodate high data rates and be sufficiently radiation hard to operate close to the beamline. The Optohybrid (OH) board for ME0, which reads out data from the front-end VFAT3b ASICs, has therefore been designed to operate without an FPGA (unlike GE1/1 and GE2/1) to ensure radiation hardness. The ME0 OH uses the radiation-hard CERN-designed lpGBT ASIC and VTRx+ optical transceiver module for high bandwidth optical links up to 10.24 Gb/s. The backend system is based on the ATCA standard. The design and development status of the readout electronics for ME0 is presented, along with recent results from integration tests performed using the first prototypes.

Development of readout electronics for the CMS ME0 muon detector

The Large Hadron Collider (LHC) in the High Luminosity (HL-LHC) era will be upgraded to deliver instantaneous luminosities up to 5 × 1 0 34 cm − 2 s − 1 , five times more than the original design value. In order to maintain performance of the Compact Muon Solenoid (CMS) Experiment under these conditions, ME0 is one of the new muon detectors to be added, along with GE1/1, GE2/1, RE3/1 and RE4/1. ME0 uses the triple Gas Electron Multiplier (GEM) technology and is designed to cover the far-forward region of 2 . 0 < | η | < 2 . 8 . The readout electronics for ME0 must be designed to deal with high data rates and be sufficiently radiation hard to operate very close to the beamline. The design and development status of the readout electronics for ME0 are presented, along with recent results from integration tests performed using the latest electronics prototypes with GEM chambers.

Experimental validation of cold neutron source performance with mesitylene moderator installed at RANS

The RANS (RIKEN Accelerator driven Neutron Source), one of compact accelerator neutron sources (CANS), tries to expand its performance by installing a cold neutron which may provide new opportunities in many applications. RANS is a low power CANS with a proton beam of 7 MeV and 100 µA at maximum. A moderator system was constructed based on results of optimization design study with mesitylene. Recently, we have done performance tests aiming at showing characteristics as cold neutron source. Cryogenic mesitylene moderator was installed on a plug with a new target moderator reflector configuration of RANS. Experiment using a gas electron multiplier (GEM) detector was carried out to measure neutron spectra of the cold moderator. This paper describes performance of the cold moderator in terms of 1) Cold neutron gain of optimization design with respect to a polyethylene moderator, 2) Temperature dependency of cold neutron spectrum flux regarding scattering kernel (SK), and 3) comparison between experiment and calculation. A note is given for comparison between calculations with different SKs available. Also, two-dimensional imaging of cold and thermal neutron spectrum flux on the viewed surface is shown with a pinhole slit configuration.

Radiation dosimetry with a Triple-GEM detector

We studied the properties of the gaseous detector triple-GEM (triple Gas Electron Multiplier) as a dosimeter with different ionizing radiation sources used in medical applications. The detector was calibrated in energy with an Iron-55 radioactive source. We measured doses of radiation from different radioactive sources as well as from a medical portable X-ray machine, and compared them to reference values. The detector presents a linear dependence between radiation intensity and measured dose. A calibration factor of 1.13x104 was found, independently of the radiation source. These results allow us to conclude that the triple-GEM detector has the potential to be used as a dosimeter in medical applications.

Test and characterisation of STS/MuCh-XYTER and integration with multiple detectors of CBM-MuCh detector systems

Compressed Baryonic Matter (CBM) is a fixed target experiment at the upcoming Facility for Anti-proton and Ion Research in Germany, having collision rates up to 10 MHz. Due to the proximity of the target and secondaries produced in absorbers, Muon Chambers (MuCh) of the CBM experiment will face a very high particle hit rate of up to 400 kHz/cm2 in its first two stations. To cope with these particle rates, a Gas Electron Multiplier (GEM) detector will be used for the first two stations while, due to relatively lower particle rates, the last two stations will use a low resistivity Bakelite Resistive Plate Chamber (RPC) detector. The electronics of these two MuCh detectors need different dynamic ranges.A Silicon Tracking Station (STS) system made of 300 μm thick silicon micro-strip sensors will be installed upstream of the MuCh detector system. The sensors will be read out through multi-line micro-cables with fast electronics. The micro-strip sensors will be double-sided with a stereo angle of 7.5°, a strip width of 58 μm, and strip lengths between 20 and 120 mm requiring high-density readout.To meet the high rate and high density requirements of MuCh and STS, respectively, a specialized 128-channel readout ASIC with a dual-gain feature is designed. This is a highly configurable ASIC with about 30,000 configurable register bits which control various bias and threshold settings of the ASIC. To integrate this ASIC with both the detector systems, detailed testing and characterization of the ASIC are required.Due to the high number of configurable registers and several operating conditions, characterizing this ASIC is very challenging. This paper describes the optimization procedures of several configurable bias parameters in detail and also explains how this ASIC is integrated with both GEM and RPC detectors of the MuCh system.

The cascade matrix electron flow amplifier based on an electron multiplier concentrator

The design and operation of a cascade matrix electron flow amplifier based on an electron concentrator multiplier is considered. Unlike classical microchannel plates, the proposed amplifier can provide a high density of output current, which also allows it to be used as a field cathode in vacuum microelectronics of giga and terahertz ranges. Keywords: Microchannel plate, secondary emission, screening, electron concentrator multiplier, field cathode.

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.

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.

A ceramic-GEM neutron detector with a wide neutron-flux measurement range for the beam monitoring at China spallation neutron source

The increase of neutron flux in pulsed spallation neutron facilities imposes demands on the neutron detector for beam monitoring, including excellent neutron/gamma discrimination, wide dynamic neutron-flux measurement range, wavelength resolution, and long-term stability. In this paper, we developed a ceramic GEM-based (gas electron multiplier) neutron detector with an active area of 100 mm × 100 mm. It adopted a thinner conversion material and the stopping layer to lower the detection efficiency so as to extend the dynamic measurement range of the detector. The detection efficiency of this detector was investigated by the Monte Carlo (MC) tool FLUKA, showing that the low efficiency around 0.01% for 1 Åneutrons was reached by using a 0.1 μm natB4C converter appended with an aluminum film of 2 μm thickness. Its validation of the wavelength spectra measurement was verified by comparisons with that made with an LND monitor, and it could work at the condition of 7.1 × 109 n/s for 2.5 Åneutrons. In addition, it was demonstrated that this detector was able to measure the beam profile with a position resolution of better than 2.1 ± 0.1 mm. The results of simulations and experiments show that this ceramic-GEM neutron detector can meet the requirements of the direct measurement of high-flux beam, and it will be a new neutron detector for the beam monitoring at the China spallation neutron source (CSNS).

Gas gain measurement for charged particle spectroscopy using glass GEM in low-pressure P-10 gas

A glass gas electron multiplier (GEM) was tested to evaluate performance for charged particle spectroscopy in a gas chamber. The test was done with varying low-pressure Ar/CH4 mixture gas (9:1, P-10) for evaluation of effective electron multiplication gain (gas gain) with the relationship between supplied voltage to GEM (GEM ΔV), energy and timing resolution of signals. The GEM ΔV is parameterized as a function of gas gain and pressure from experimental results. The signal-to-noise ratio on the anode signal was significantly improved due to electron multiplication by the glass GEM in comparison with traditional grid gas ionization chamber. A test using Ar/CO2 mixture gas (9:1) shows that GEM ΔV is successfully reduced with keeping gas gain and energy resolution comparable. Time difference between anode and cathode signals behaves reasonably with drift time of initial electrons. We conclude that charged particle spectrometer using glass GEM can be designed by using obtained parameter. The spectrometer is useful especially for low energy charged particle due to the gas gain.

Upgrade of the BM@N detector for studies of heavy ion interactions

In the next years the Baryonic Matter at Nuclotron (BM@N) experiment at Joint Institute for Nuclear Research (JINR) will carry out the physics program with heavy ion beams with energies up to 3.9 AGeV and intensities up to 2 [Formula: see text] ions/s. The experiment is devoted to measure observables sensitive to the equation of state of dense baryonic matter. To meet this goal the existing BM@N set-up will be upgraded with fast hybrid tracking system, which includes beam tracking detectors, a large aperture silicon tracking system, gas electron multiplier stations and cathode strip chambers. The measurement of the event plane and centrality will be achieved with a forward hadron calorimeter and granular hodoscopes. The physics program and configuration of the upgraded BM@N set-up are presented.

Commissioning and operation in magnetic field of CMS GE1/1 station

In October and November 2021 the CMS Gas Electron Multiplier (GEM) detectors of station GE1/1 were operated for the first time in presence of a magnetic field in CMS.The phenomena observed in this first period led to performing a test on GE1/1 chambers to study their behaviour in presence of a magnetic field ramp. The magnetic field has been created using the Goliath magnet installed in the CERN North Area.The aim of the test is to determine if a magnetic field ramp causes serious problems to the operation of the GEM chambers and to develop a clear set of procedures, that will permit the safe operations of the GEM chambers during a magnetic field ramp.

Experimental study of channel electron multiplier

Experimental study of channel electron multiplier

Development and operation of the CGEM Inner Tracker for the BESIII experiment

The extension of data acquisition for the BEijing Spectrometer (BESIII) experiment until at least 2030 has resulted in upgrades to both the accelerator and the detector. An innovative Cylindrical Gas Electron Multiplier (CGEM) is under construction to upgrade the inner tracker, which is suffering from aging. The CGEM Inner Tracker (CGEM-IT) was designed to restore efficiency and enhance the reconstruction of the secondary vertexes position. Reconstruction in the magnetic field of 1 T requires an analog readout and an electronic contribution to the time resolution better than 5 ns. The entire system consists of about 10,000 electronic channels and must maintain a peak rate of 14 kHz/strip of signal hits for the innermost layer of the CGEM-IT. The CGEM readout system is based on the innovative TIGER ASIC, which is manufactured using 110 nm CMOS technology. A special readout chain consisting of GEM Read Out Cards (GEMROC) was developed for data acquisition. Two of three layers, equipped with the final electronics, have been operating in Beijing since January 2020 collecting cosmic ray data in a test facility, remotely controlled by the Italian group due to the pandemic situation. Since it was not possible to perform further tests on the cylindrical detector, in July 2021, a test beam was conducted at CERN with the final electronics configuration on a small prototype consisting of four triple-GEM planar detectors. In this presentation, the general status of the project CGEM-IT will be presented, with particular emphasis on the results of the test beam data collection.

Study on the wide range gamma dose rate response for a new type thick gas electron multiplier

Study on the wide range gamma dose rate response for a new type thick gas electron multiplier