Multi-gap Resistive Plate Chamber Research Articles

Glass multi-gap RPCs for photon-transmission imaging

In the present R&D, multi-gap resistive plate chambers (MRPCs) are studied for photon non-destructive inspection of small airport baggages and cargos. Six-gap RPCs for line-scan operations are constructed with soda-lime glass with a thicknesses of 0.53 mm. The typical detector characteristics such as the operation high voltage (HV), the efficiency, and the strip multiplicity are measured by using 661.7 keV photons emitted from a 137Cs source with a current activity of 4.74 GBq. The efficiency for the 661.7 keV photons measured by the MRPC detector at the HV applied to obtain the photon-transmission images is 5.5%, which is about 84% of that predicted by a GEANT simulation. To demonstrate the quality operation of the MRPC detectors, we conduct line-scan operations for various objects and produce the photon-transmission images that barely identify 2 mm-thick stainless steel objects when measured with a color depth (contrast) of the image pixels of about 100.

Development of a sealed MRPC with high time resolution

Multi-gap Resistive Plate Chambers (MRPC) are used in the Solenoidal Large Intensity Device (SoLID) at Jefferson Lab (JLab) to identify kaons. SoLID requires 20 ps for the total time resolution. In this paper, a sealed MRPC (sMRPC) prototype with 4 stacks and 7 uniform gas gaps is designed to reach a good time resolution. At the same time, sMRPC can lower the airflow through the chamber to reduce the greenhouse pollution. Both analog signal discrimination & TDC electronic system and waveform sampling electronic system are used for the readout of the signal. In cosmic tests, we compared the time resolution of these electronic readout methods and measured the efficiency of the sealed MRPC. The preliminary result shows that the MRPC prototype has an efficiency higher than 95%. The sealed MRPC prototype using waveform sampling system, has a time resolution of 40 ps, while a 54 ps time resolution is obtained using analog signal discrimination & TDC electronic system.

A large-area MRPC detector for muon scattering tomography

A muon telescope equipped with four multi-gap Resistive Plate Chambers of 2 m2 per plane was tested with the muon scattering tomography technique. The telescope was operated during several hours with high atomic number materials located at its center with two detector planes on each side. With an intrinsic efficiency above 98%, spatial resolution around 1 cm and detector planes spaced by 45 cm, it was possible to identify the presence of a 5 cm thick tungsten block in 10 min of acquisition. The results obtained after five hours of acquisition are also presented in this communication.

Aging suppression, high time resolution and 2D-position sensitive Multi-Strip Multi-Gap Resistive Plate Counter for high rate experiments

The multi-strip, multi-gap resistive plate chambers (MSMGRPCs) of the Time of Flight (TOF) wall of the Compressed Baryonic Matter (CBM) experiment will be exposed to challenging counting rates, up to 50 kHz/cm2. The unprecedented requirement to the CBM-TOF chambers to keep their performance (efficiency over 90% and system time resolution better than 80 ps) at these high counting rates has triggered the development of a new generation of MSMGRPCs with increased counting rate capabilities and suppression of aging effect in high irradiation environment. The MSMGRPCs designed for the low polar angles region of the CBM-TOF wall, besides performing in high counting rate, should also maintain their performance over the lifetime of the experiment. Detailed aging investigation evidenced mainly a gas pollution effect for the chambers with gas exchange via diffusion, enhanced around the spacers. In order to mitigate this phenomenon, a MSMGRPC prototype with a direct gas flow through the gas gaps and a reduced number of spacers in the electric field was developed. Assembling and tests of such prototypes as well as the results of the first aging investigations performed exposing the chamber to a high intensity X-ray flux at different gas flow rates and gas mixtures are reported.

Studies on new Eco-gas mixtures for Extreme Energy Events Project

The Extreme Energy Events (EEE) experiment, a joint project of the Centro Fermi and INFN Italian national research institutes, has a dual purpose: a scientific research program for measurements of the cosmic rays flux at ground level and an intense outreach and educational program with an active contribution of students and teachers in the construction and operation of the detectors in High Schools. The network counts 60 tracking detectors, each made by three Multigap Resistive Plate Chambers (MRPC), operated so far with a gas mixture composed by 98% C2H2F4 and 2% SF6. Given its high Global Warming Potential (GWP), the collaboration, since few years, started a R&D on alternative mixtures environmentally sustainable. Latest results on a C3H2F4 + He eco-friendly mixture are here presented.

Reduction of Greenhouse Gases impact in the EEE Project

The whole Extreme Energy Events (EEE) array is composed of 61 telescopes installed in Italian High Schools, built and operated by students and teachers, constantly supervised by researchers. The muon telescope of the EEE Project is made by 3 Multigap Resistive Plate Chambers (MRPC). The unconventional working sites are a unique test field for checking the robustness and the low-ageing features of the MRPC technology for particle tracking and timing purposes. The MRPCs are fluxed with a standard mixture (98% C2H2F4 - 2% SF6) of greenhouse gases (GHG) phasing out of production. The EEE Collaboration is currently studying alternative mixtures environmentally and economically sustainable. The EEE Collaboration actions to reduce the Global Warming Potential (GWP) in the MRPC array of the EEE experiment are progressing.

Simulation tool for MRPC telescopes of EEE experiment

The Extreme Energy Events (EEE) experiment consists in a network of cosmic muon tracker telescopes, each made of three Multi-gap Resistive Plate Chambers (MRPC), able to precisely measure the absolute muon crossing time and the muon integrated angular flux at the ground level. To investigate the MRPC telescope response and performance, a simulation tool was developed in GEMC, software package based on GEANT4 libraries. The framework was validated by comparing simulations with the EEE experimental data. Detailed description of telescope response is fundamental to carry on the physics program of the EEE project, and it could open other research avenues, such as using the telescope in combination with other detectors to perform a (muon) tomography of material surrounding the telescope. In this paper, the EEE simulation framework will be presented reporting results and discussing further applications.

A cosmic muon test facility with the MRPC telescopes of the EEE Project

The Extreme Energy Events (EEE) ‘telescope’ is made by 3 Multigap Resistive Plate Chambers (MRPC), each with an active area of 158x82 cm2 in size. Each detector is part of a large network of about sixty telescopes spread over the Italian territory. Due to the good tracking capabilities (100 ps time resolution and cm2 spatial resolution) the EEE telescope can be used also as test station for large area detectors. The link between the EEE track and signals from the detector under test can be obtained by implementing a streaming DAQ with a common time reference between the two systems given by the GPS signal. The installation and first results of the cosmic muon test facility with the EEE MRPC telescope based on the low-cost, streaming-compatible 12 channels, 250MHz, 14 bits digitizer (INFN-WaveBoard or WB) developed by the JLAB12 Collaboration, is presented.

CEE inner TOF prototype design and preliminary test results

The Cooling Storage Ring (CSR) External-target Experiment (CEE) is the first multi-purpose nuclear physics experimental device to operate in the GeV energy range at the Heavy-Ion Research Facility (HIRFL-CSR) in Lanzhou, China.The primary goals of the CEE are to study the bulk properties of dense matter and to understand the quantum chromo-dynamic (QCD) phase diagram by measuring the charged particles produced in heavy-ion collisions at the target region with large acceptance. An inner time of flight (iTOF) system has been proposed to measure the multiplicity, angular distribution, and time information of the charged particles. Herein, we introduce the performance requirements of iTOF according to calculations and GEANT4 simulations. The proposed system is characterized by high granularity and time performance, hence, the conceptual design of the iTOF wall adopts high granularity Multi-gap Resistive Plate Chambers (MRPC) with a time resolution around 30 ps. To evaluate the MRPC design, the cosmic ray test was performed. A timing resolution better than 28 ps and an efficiency better than 98% have been achieved for MIPs, as interpreted by the cosmic ray GEANT4 simulation of time jitter components.

Beam test results of the MRPC prototype for the new NA61/SHINE ToF system

A new Time-of-Flight (ToF) detector of the NA61/SHINE hadron spectrometer at CERN SPS based on Multigap Resistive Plate Chambers (MRPCs) technology is offered as a substitution of the scintillation ToF detector developed in 1990s. In 2019–2020, a prototype module of the new ToF system was tested on the 280 MeV/c positron beam to determine its characteristics. The analogue front-end electronics and DRS4-based waveform digitizer were used as a readout chain. This article presents the results of the MRPC test with analogue readout obtained in 2019–2020.

The extreme energy events project: Bring science inside schools.

The Extreme Energy Events Project is an experiment devoted to the study of cosmic ray physics. It consists in a network of about 60 detectors based on the Multigap-Resistive Plate Chamber technology, distributed in the Italian territory and at CERN. In particular, the detectors are installed in high-school buildings, and the scientific activity is carried on in strong cooperation with students and professors. In this perspective, the project relies on citizen science, since non-professional people are fully involved in the constant monitoring of the operations. Furthermore, students participate in many stages of the scientific process, from the building of the detectors at CERN to the installation and commissioning of the telescopes inside their schools, to data collection and analysis, and to publication and dissemination of results.

Underground muon flux measured by EEE students

The Extreme Energy Events experiment (EEE) is a cosmic ray observatory made of about 60 muon telescopes based on Multigap Resistive Plate Chamber (MRPC) detectors. The EEE experiment has two main targets: a scientific and a dissemination. The EEE collaboration has also developed a large set of portable scintillator-based detectors, named Cosmic Box (CB), mainly used for educational purposes. The CB allows students to perform cosmic ray counting measurements in several environments. CBs are made of two 15 × 15 × 1 cm scintillators read by two 3 × 3 mm2 SiPMs operated in coincidence. Three CBs were deployed in Nuraxi Figus and Seruci coal mine to perform an underground measurement of the cosmic muon flux attenuation. High school and university students were directly involved in all the stages of the measurements: from the preliminary measurements to the on-site work and data analysis.

Readout Electronics Prototype of TOF Detectors in CEE of HIRFL

In the Cooling storage ring External-target Experiment (CEE) in heavy ion research facility in Lanzhou (HIRFL), multigap resistive plate chambers (MRPCs) detectors are used for high-precision time-of-flight (TOF) measurement to identify the scattered particles after the ion beam hits the target. Regarding the external TOF (eTOF) and 2/3 internal TOF (iTOF) detectors, a ~25-ps rms time precision is required for the readout electronics, whereas for the other 1/3 iTOF detectors, a ~10-ps rms precision is required. A readout electronics prototype was designed, including the front-end electronics (FEE) based on analog signal amplification, discrimination, and the time-to-digital module (TDM), based on field-programmable gate array (FPGA) time-to-digital converter (TDC), to achieve high-precision time measurement. PreAmplifier-DIscriminator (PADI) is used in the design of the FEE, while an FPGA TDC, based on tapped delay line (TDL) structure, with a time precision performance better than 5-ps rms, is implemented in the TDM, as well as the trigger matching circuit and other control logic. The performance of the whole system was tested under different input signal charges and the results indicated that the time precision is better than 10-ps rms, which satisfies the application requirements.

Fabrication and testing of Novel 20 gas gaps double-stack Multi-gap Resistive Plate Chamber (MRPC) with multi-layer Copper converters and reduced HV for high energy gamma detection

Resistive Plate Chambers (RPCs) are cost-effective detectors with fast signal, excellent time and spatial resolution for charged particle detection. These detectors can be also good candidates for medical imaging purposes like PET. Although, low efficiency of gaseous detectors limits their usage for high energy gamma detection, but it is possible to improve the detection efficiency by proper gamma to electron converter material and multi-layers of RPCs (MRPCs). In common RPCs, increasing the number of layers is limited by the large amount of applied High Voltage (HV). To overcome this problem, which is important for secure medical imaging system, the double-stack mode configuration is used in such a way that the RPCs are physically serial, but electrically parallel. In this work, A 20 gap MRPC with 160μ m of Copper converters and 150μ m gas gaps is fabricated. For this purpose, each metal sheet sandwiched between two thin resistive glasses. The metal electrodes are also used to apply separate HV to each gas gap. By using the proposed configuration, the applied HV can be reduced to 1.2kV for whole system. The simulation results show that the detection efficiency for 661keV Cs-137 gammas with 160μ m of Copper converter is around %5, which is in good agreement with experimental results.

The High-Rate Sealed MRPC to Promote Pollutant Exchange in Gas Gaps: Status on the Development and Observations

This work reports the latest observations on the behavior of two Multigap Resistive Plate Chambers (MRPC) under wide high-luminosity exposures, which motivate the development and in-beam test of the sealed MRPC prototype assembled with low-resistive glass. The operation currently being monitored, together with previous simulation results, shows the impact of gas pollution caused by avalanches in gas gaps, and the necessity to shrink the gas-streaming volume. With the lateral edge of the detector sealed by a 3D-printed frame, a reduced gas-streaming volume of ~170 mL has been achieved for a direct gas flow to the active area. A high-rate test of the sealed MRPC prototype shows that, ensuring a 97% efficiency and 70 ps time resolution, the sealed design results in a stable operation current behavior at a counting rate of 3–5 kHz/cm2. The sealed MRPC will become a potential solution for future high luminosity applications.

The cosmic muon and detector simulation framework of the extreme energy events (EEE) experiment

This paper describes the simulation framework of the extreme energy events (EEE) experiment. EEE is a network of cosmic muon trackers, each made of three multi-gap resistive plate chambers (MRPC), able to precisely measure the absolute muon crossing time and the muon integrated angular flux at the ground level. The response of a single MRPC and the combination of three chambers have been implemented in a GEANT4-based framework (GEMC) to study the telescope response. The detector geometry, as well as details about the surrounding materials and the location of the telescopes have been included in the simulations in order to realistically reproduce the experimental set-up of each telescope. A model based on the latest parametrization of the cosmic muon flux has been used to generate single muon events. After validating the framework by comparing simulations to selected EEE telescope data, it has been used to determine detector parameters not accessible by analysing experimental data only, such as detection efficiency, angular and spatial resolution.

The EEE Multigap Resistive Plate Chambers as tracking devices to monitor the stability of a civil building

Due to their efficiency, tracking capabilities and long-term operational conditions, Multigap Resistive Plate Chambers (MRPC) may be used in a stable location in coincidence with additional detectors fixed to other parts of a civil building, to detect relative displacements of different parts of the building due to long term deformations of the structure. In this contribution we report the results of two different measurements carried out in the Department of Physics and Astronomy of the University of Catania (with three floors above the ground and an underground basement), using one of the MRPC telescopes of the Extreme Energy Events project, in coincidence with two scintillator-based muon telescopes located in various positions inside the building. Experimental results obtained by these measurements campaigns over a period of about three months are reported, together with a discussion about the performance of the technique. The sensitivity of the method is also discussed by means of Monte Carlo simulations.

A new MRPC prototype with diamond-like-carbon coated glass electrodes

The Multi-gap Resistive Plate Chamber (MRPC) has been used in many high energy physics and nuclear experiments in the last decade, such as ALICE [1] and STAR [2]. Normally, the MRPC is built with commercial floating glass (bulk resistivity ρ≈ 1012Ω· cm), which limits the rate capability to less than 1 kHz/cm2. In modern high energy physics, with the increase of colliders beam energy and luminosity, the rate capability of MRPC has to be enhanced accordingly. One normal way is to decrease the bulk resistivity ρ of the resistive plate, as the low resistive glass developed by Tsinghua University for the CBM experiment [3]. Alternatively, the surface of the electrode is also a possible path for the neutralization of the avalanche charges. Recently, we managed to carry this method out by coating a Diamond-Like-Carbon (DLC) layer on the surface of the floating glass. The DLC layer, realized by the magnetron sputtering method, has very good physical and chemical stability. The demanded surface resistivity can be achieved easily. A series of DLC-coated glasses with different resistivity has been tested in our lab. We have also made some MRPC prototypes and tested them with cosmic rays. Some preliminar results, including the operating current, the efficiency and the time resolution, have been achieved. More research is ongoing to improve the design and performance of this new method of increasing the rate capability of MRPC.

Multigap Resistive Plate Chambers for Time of Flight Applications

With the advantages of high-performance, easy to build and relatively low cost, the multigap resistive plate chamber has been arousing broad interests over the last few decades. It has become a new standard technology for the time of flight system in high energy physics experiments. In this article, we will give a description of the structure and the operating principles of the MRPC detector and focus on reviewing the applications on the time of flight system in several famous experiments. The performances, including time resolution and particle identification, are discussed in detail. Some recent advances and points of view for the future development of the next generation MRPC are also outlined.

MRPC technology for muon tomography

Muon tomography is an innovative high-Z material detection technology developed in recent years. The most crucial part of this technology is the high position resolution detectors used for the muon track reconstruction. Multi-Gap Resistive Plate Chambers (MRPCs in the following) are gaseous detectors first developed at CERN in middle 1990s. Considering their characteristics in terms of high efficiency, low cost, robust structure, and excellent position resolution, MRPC became the detector of choice for the TUMUTY (Tsinghua University cosmic ray muon tomography facility) system built in 2012. This paper features a summary about the latest developments on MRPC technology for muon tomography. After the success of the TUMUTY prototype, researches were carried out on larger sensitive area position resolution MRPCs with 2-D readout, and on environment-friendly sealed MRPCs (SMRPC) for industrial applications and future muon tomography systems. It was studied how encoding readout methods and external environment influence the performance of MRPC detectors. Also, an MRPC simulation frame and new data processing methods were both developed, which have provided useful information on optimal design of the future position resolution MRPCs and muon tracking systems.