XIV Workshop on Resistive Plate Chambers and related detectors

The India-based Neutrino Observatory (INO) is a project aimed at building a large underground laboratory to explore the Earth's mater effects on the atmospheric neutrinos in multi-GeV range. INO will host a 50 kton magnetized iron calorimeter detector (ICAL) in which Resistive Plate Chambers(RPCs) will be the active detector elements. In ICAL, 28,800 glass RPCs of 2 m × 2 m size will be operated in the avalanche mode. A small variation in the compositions of ionizing gaseous medium in the RPC affects its performance. Study of the charge distribution of the RPC at different gas compositions is necessary to optimize the gas mixture. An RPC made with glass plates of dimension 30 cm × 30 cm was operated in avalanche mode with a gas mixture of C ₂H ₂F ₄/iC ₄H ₁₀/SF ₆. We have studied the performance of these RPCs at the same ambient conditions. The percentages of the iC ₄H ₁₀ or SF ₆ were varied and its effect on the performance of RPC were studied. The study of the charge distribution and time resolution of the RPC signals at different gas compositions is presented in this paper.

A new particle detector with sub-nanosecond time resolution capable of working in high-rate environment (rate capability of the order of MHz cm ²) is under developmnet. Semi-conductive electrodes with resistivity ρ up to 10 ⁸ Ωcm have been used to improve the RPC [1,2] rate capability. In this paper efficiency and time resolution of three different detector structures are presented.

In recent years, the cosmic-ray muon imaging technique has been widely used in industrial practical applications, such as the nuclear reactor monitoring and the internal container scanning. However, it is restricted by the lagging imaging algorithm technology, resulting in poor image quality and time-consuming. In this study, a cosmic-ray imaging system of Gas Electron Multiplier (GEM) has been constructed with the help of the Filter Back Projection (FBP) algorithm. Aiming at the dry spent fuel storage casks of Westinghouse MC-10, two different imaging algorithms are carried out. Two reasons are proposed by comparing their effects on the constructed image quality. The results demonstrate that the scattered reconstructed image is more sharply resolved than the transmitted one, and the sharpness of the edge is increased by 20%. The outline and missing part of the fuel assembly in the cask can be displayed clearly by using this method, even if the position resolution of the gas detector is only 300 μm.

The Multigap Resistive Plate Chambers (MRPC) are used as a timing detector in several particle physics and cosmic ray experiments. The gas mixture of MRPC at current experiments is a mixture containing C ₂F ₄H ₂ and in some cases SF ₆. C ₂F ₄H ₂ and SF ₆ have a Global Warming Potential (GWP) of 1430 and 23900 respectively, therefore they are classified as greenhouse gases. The studies to reduce the amount of emission of the greenhouse gas in high energy experiments are underway; the present contribution has been performed as part of this effort. The results have been obtained from the beam test of a small MRPC which has 6 gaps of 220 μm and a sensitive area of 20 × 20 cm ². It has been operated with the ecological HFO-1234ze gas (C ₃F ₄H ₂), and with the C ₂F ₄H ₂/SF ₆ mixture. We have found that the ecological gas can substitute for the C ₂F ₄H ₂-based gas mixture without significantly compromising the current level of performance.

The CMS experiment, located at the Large Hadron Collider (LHC) in CERN, has a redundant muon system composed by three different gaseous detector technologies: Cathode Strip Chambers (in the forward regions), Drift Tubes (in the central region), and Resistive Plate Chambers (both its central and forward regions). All three are used for muon reconstruction and triggering. The CMS RPC system confers robustness and redundancy to the muon trigger. The RPC system operation in the challenging background and pileup conditions of the LHC environment is presented. The RPC system provides information to all muon track finders and thus contributing to both muon trigger and reconstruction. The summary of the detector performance results obtained with proton-proton collision at √ s = 13 TeV during 2016 and 2017 data taking have been presented. The stability of the system is presented in terms of efficiency and cluster size vs time and increasing instantaneous luminosity. Data-driven predictions about the expected performance during High Luminosity LHC (HL-LHC) stage have been reported.

Several theoretical models inspired by the idea of supersymmetry (SUSY) accommodate the possibility of Heavy Stable Charged Particles (HSCPs). The Phase II upgrade of the CMS-RPC system will allow the trigger and identification of this kind of particles exploiting the Time-of-Flight Technique with the improved time resolution that a new Data Acquisition System (DAQ) system will provide (~2 ns). Moreover, new Resistive Plate Chambers (RPC) detector chambers will be installed to extend the acceptance coverage up to |η|<2.4 with similar time resolution and better spatial resolution. We present a trigger strategy to detect HSCPs with the RPC detectors. Its performance is studied with Monte Carlo simulations and the expected results with the High Luminosity Large Hadron Collider (HL-LHC) data are shown.

Based on previous experience and attempt, a real-size mosaic Multi-gap Resistive Plate Chamber (MRPC) has been developed within the framework of the CMS muon upgrade efforts. The chamber is a 5-gap with plates made each of 6 pieces of low resistive glass. Cosmic ray test at CERN 904 shows that its efficiency can reach above 95% with a gas mixture of 90% C ₂H ₂F ₄, 5% i-C ₄H ₁₀ and 5% SF ₆. The chamber was also tested with CMS dry gas(95.2% C ₂H ₂F ₄, 4.5% i-C ₄H ₁₀, 0.3% SF ₆) at the CERN Gamma Irradiation Facility (GIF++). Efficiency results calculated by a simple tracking method show that the good performance is maintained at rates up to 10 kHz/cm ².

The High Luminosity LHC (HL-LHC) phase is designed to increase by an order of magnitude the amount of data to be collected by the LHC experiments. The foreseen gradual increase of the instantaneous luminosity of up to more than twice its nominal value of 10×10 ³⁴cm ^-1s ^-2 during Phase I and Phase II of the LHC running, presents special challenges for the experiments. The region with high pseudo rapidity (η) region of the forward muon spectrometer (2.4 >|η| > 1.9) is not equipped with RPC stations. The increase of the expected particles rate up to 2 kHz cm ^-2 (including a safety factor 3) motivates the installation of RPC chambers to guarantee redundancy with the CSC chambers already present. The current CMS RPC technology cannot sustain the expected background level. A new generation of Glass-RPC (GRPC) using low-resistivity glass was proposed to equip the two most far away of the four high η muon stations of CMS. In their single-gap version they can stand rates of few kHz cm ^-2. Their time precision of about 1 ns can allow to reduce the noise contribution leading to an improvement of the trigger rate. The proposed design for large size chambers is examined and some preliminary results obtained during beam tests at Gamma Irradiation Facility (GIF++) and Super Proton Synchrotron (SPS) at CERN are shown. They were performed to validate the capability of such detectors to support high irradiation environment with limited consequence on their efficiency.

The high pseudorapidity (η) region of the Compact Muon Solenoid (CMS) muon system is covered by Cathode Strip Chambers only and lacks redundant coverage despite the fact that it is a challenging region for muons in terms of backgrounds and momentum resolution. During the annual Year-End Technical Stops 2022 & 2023, two new layers of improved Resistive Plate Chambers (iRPC) will be added, RE3/1 & RE4/1, which will completely cover the region of 1.8 < |η| < 2.4 in the endcap. Thus, the additional new chambers will lead to an increased efficiency for both trigger and offline reconstruction in the difficult region where the background is the highest and the magnetic field is the lowest within the muon system. The extended RPC system will improve the performance and the robustness of the muon trigger. The final design of iRPC chambers and the procedure to integrate and install them in the CMS muon system have been finalized. In this report, the main results demonstrating the implementation and installation of the new iRPC detectors in the CMS muon system at high |η| region will be presented.

We measure the efficiency of CMS Resistive Plate Chamber (RPC) detectors in proton-proton collisions at the centre-of-mass energy of 13 TeV using the tag-and-probe method. A muon from a Z ⁰ boson decay is selected as a probe of efficiency measurement, reconstructed using the CMS inner tracker and the rest of CMS muon systems. The overall efficiency of CMS RPC chambers during the 2016–2017 collision runs is measured to be more than 96% for the nominal RPC chambers.

The Resistive Plate Chamber (RPC) system covers the barrel region of the ATLAS muon spectrometer [1] in the pseudo-rapidity range |η|<1.05, with six independent detector layers exclusively providing the first level trigger signal and the track coordinate in the non-bending plane of the muon candidates. The system is designed to operate up to the nominal Large Hadron Collider luminosity (   = 10 ³⁴  cm ⁻² s ⁻¹) which has been already exceeded thanks to the excellent performance of the collider. The experience in operating the present RPC system, up to the maximum instantaneous luminosity of  2.06 × 10  ³⁴ cm ⁻² s ⁻¹ reached in 2017, is reported. The performance of the system, in the severe background and pileup conditions of the last data taking period, is presented together with the improved tools implemented in order to have an effective monitoring of the detector status. The plans to successfully operate the present system during the HL-LHC phase are also introduced.

The upgrade of the Resistive Plate Chamber (RPC) detector, in order to increase the detector rate capability and to be able to work efficiently in high rate environment, consists in the reduction of the operating voltage along with the detection of signals which are few hundred μV small. The approach chosen by this project to achieve this objective is to develop a new kind of Front End electronics which, thanks to a mixed technology in Silicon and Silicon-Germanium, enhance the detector performances increasing its rate capability. The Front End developed is composed by a preamplifier in Silicon BJT technology with a very low inner noise (1000 e ⁻ rms) and an amplification factor of 0.3–0.4 mV/fC and a new kind of discriminator in SiGe HJT technology which allows a minimum threshold of the order of 0.5 mV. The performances of this kind of Front End will be shown. The results are obtained by using the CERN H8 beamline with a full-size RPC chamber of 1 mm gas gap and 1.2 mm thickness of electrodes equipped with this kind of Front End electronics.

ZDAQ is a light data acquisition system, based on ZeroMQ and mongoose-cpp networking frameworks. Providing binary data collection, events building, web accessible finite state machine and process control, it is well suited to manage distributed data source of laboratory or beam test. It provides a simple event building (one unique process, no parallel building) with flexible data writing formats. It is intensively used for the tests of the Semi Digital HCAL (RPC+Fe) prototype designed for ILD and also for the tests of the new electronic for improved RPC (CMS HL-LHC upgrade)

We propose a unconventional calorimetry approach. The method is based on idea used for the first time in the energy determination of extensive air showers (EAS) at very high energy (> 100 TeV). It has some peculiar characteristics which can be summarized in the following two points: a) measurement of the shower energy by means of a single sampling; b) measurement of the lateral density distribution of charged particles around the shower axis. We studied the validation of this measurement technique to lower energies (100 GeV–10 TeV) by MC calculation.

The Resistive Plate Chambers (RPC) are used for muon triggers in the CMS experiment. To calibrate the high voltage working-points (WP) and identify degraded detectors due to radiation or chemical damage, a high voltage scan has been performed using 2017 data from pp collisions at a center-of-mass energy of 13 TeV. In this paper, we present the calibration method and the latest results obtained for the 2017 data. A comparison with all scans taken since 2011 is considered to investigate the stability of the detector performance in time.

The high luminosity expected from the HL-LHC will be a challenge for the CMS detector. The increased rate of particles coming from the collisions and the radioactivity induced in the detector material could cause significant damage and result in a progressive degradation of its performance. Simulation studies are very useful in these scenarios as they allow one to study the radiation environment and the impact on detector performance. Results are presented for CMS RPC stations considering the operating conditions expected at the HL-LHC.

The India-based Neutrino Observatory (INO) is an approved multi-institutional experiment of India. It will use maximum 30,000 Resistive Plate Chamber (RPC) of size 2 m × 2 m as an active detector in which each will be sandwiched between two iron plates. Each RPC detectors will be made up of 3 mm thick glass (or Bakelite) plates whose one surface will be coated with graphite paint to work as electrode. To achieve effective and uniform electric field, the coated graphite paint must have uniform distribution over the glass surface. Uniformity can be demonstrated by measuring the surface resistance of the coated graphite paint. However, manual measurement of 60,000 electrodes with the help of multimeter and the jig demands huge amount of person-hour with compromised accuracy, and therefore that requires the need and importance of the automatic scanning system. We have designed an advanced automatic scanning system (ASS) has been developed to fulfill the required needs and overcome the shortcomings of the initially developed system. Measurements are sensitive to the contact pressure between the jig and RPC electrode surface. In this paper, various parameters of the ASS have been precisely fixed. Obtained results are compared with the standard one and found satisfactory within error. It is observed that for obtaining the correct and safe value of surface resistance, applied pressure value in terms of force should be in the range of (9–11) Newton.

Resistive Plate Chamber (RPC) detectors are widely used thanks to their excellent time resolution and low production cost. The large RPC systems at the CERN-LHC experiments are operated in avalanche mode thanks to a R134a-based gas mixture with the addition SF ₆ and iC ₄H ₁₀ in low concentrations (0.3% and 5% respectively). However, due to their high global warming potential (GWP), R134a has been phased out from production and SF ₆ will be probably phased out very soon. Although R134a and SF ₆ will always be technically available for research purposes, their cost will probably increase as the interest of industry and market will gradually move towards new eco-friendly refrigerants and insulators. In addition, the reduction of R134a and SF ₆ emission in the atmosphere from anthropogenic activityis is of paramount importance because GHGs are believed to be at the origin of climate changes. Several gas mixtures based on new environmental friendly gases have been tested in the past few years. Results obtained with new gas mixtures based on hydro-fluoro-olephin (R1234ze), CO ₂ and C ₄F ₈O are presented. A parallel strategy for reducing the GHG emission is focused on the development of new gas recirculation and recuperation systems. The present contribution describes the last results obtained during the first test of RPC detectors operated with new environmental friendly gas mixture and new gas recirculation system. Other strategies for GHG emission reduction will be discussed as a part of a wider R&D program.

We discuss the possibility of hosting a big Astrophysics ground-based experiment in Ecuador aimed to detect VHE particles. Ecuador location makes possible to see both the Northern and Southern sky. An additional geographic feature is the presence of one of the highest American mountains, the Chimborazo (6310 m.a.s.l.), that happen to be the highest point on Earth measured from the center of the planet. In the last decade Ecuadorian government has invested resources in higher education and research, with an important policy of training abroad. The effect has been that now many researchers in Physics, Astrophysics, and Engineering are working in universities across the country and collaborating with important experiments like CMS at CERN, Pierre Auger in Argentina, HAWK in Mexico and in LAGO project. All these features make Ecuador an ideal place to host a big VHE particle detector experiment in South America.

Resistive plate chambers are studied for in-vivo beam verification in particle therapy. A four-gap glass RPC is constructed with 1.1-mm-thick floating glass and tested with 662-keV gamma rays emitted from a 5-GBq ¹³⁷Cs source, as well as high-energy photons induced by 140-MeV raster-scan-mode proton beams provided by the Samsung Proton Therapy Center. The desired 3 mm resolution of the RPC detector is confirmed by reconstructing gamma transmission images for the cesium gammas gathered from the data. Using the described RPC detector and a 10-cm-thick lead collimator, we obtain two-dimensional gamma-ray images for 140-MeV proton beams and confirm the detector technology proposed in the present research.

The CBM (Compressed Baryonic Matter) experiment constructed at FAIR (Facility for Anti-proton and Ion Research) at GSI, Darmstadt, Germany, will provide unique research opportunities to explore the phase diagram of nuclear matter. As one of the core detectors in the CBM experiment, the Time-of-Flight (TOF) system applies the MRPC (Multi-gap Resistive Plate Chamber) for a precise particle identification for all the incident charged hadrons. The CBM-TOF will be operated at an ion beam intensity up to 10 ⁹/s, which means the particle fluxes on the TOF wall can reach an unprecedentedly high rate of 30 kHz/cm ². Almost half of the MRPC counters are from the inner region of the TOF wall, and they will be assembled with the low-resistive glass which enables them to work under such high rate. This is the first time of the large scale application of the low-resistive glass MRPCs into the nuclear and high-energy physics experiments. It is especially important to study on the production and test procedure to keep the good performance of all these counters. For this mass production, we have developed a set of specified manufacturing procedure and quality control method to guarantee the performance of all the counters. A newly developed method to check the uniformity of the gas gap with help of the projection imaging technique has been first applied. Until now, 73 MRPCs have been produced for the eTOF project in the BESII detector upgrade at STAR and the TOF system of mini-CBM. Tested by cosmic ray in a system based on TRB, all the produced counters show a stable performance of above 95% efficiency and below 90 ps time resolution. The study on the mass production of the low-resistive plate chamber will provide experience for wide application of MRPC into the high rate experiments in the future. In this paper, the counter design, manufacturing procedures, quality control methods and test results for this MRPC counter are described in a detailed way.

The main function of HIRFL-CSR external target experiment (CEE) is to detect the final-state particles produced in heavy-ion collisions with large acceptance, and provide important measurements to understand foundamental questions in the nuclear physics field, e.g. the nuclear equation of state in high baryon number density and the nuclear phase diagram. A new T0/Trigger detector based on multi-gap resistive plate chamber (MRPC) technology has been constructed and tested for the CEE. It measures the multiplicity and timing information of particles produced in heavy-ion collisions at the target region, providing necessary event collision time (T0) and collision centrality with high precision. Monte-Carlo simulation shows a time resolution of several tens of picosecond can be achieved at central collisions. The experimental tests have been performed for this prototype detector with both hadron beam and heavy-ion beam. The preliminary results are shown to demonstrate the performance of the T0/Trigger detector.

In this paper we review the performances of the RPC detector versus the parameters characterizing the front-end electronics. The use of RPCs in collider experiments required a substantial increase of the rate capability compared to what could be reached in streamer working mode. That was achieved working in saturated avalanche mode, where the charge delivered in the gas was much lower than in streamer mode. The High luminosity LHC and the future colliders will require even larger rate capability in the muon spectrometers compared to the current one, which can be obtained with a further improvement of the front-end electronics. This improvement consist in lowering the front-end threshold in order to detect lower charge avalanches and at the same time to improve the signal to noise ratio.

A new type of RPC chamber prototype, consisting of a triplet of 50×100 cm ² RPCs, having 1 mm gas gap, 1.2 mm electrodes and new high sensitivity front end electronics, has been designed for the HL-LHC ATLAS upgrade program. Beam test of this prototype chamber was performed in GIF++ using 100 GeV muons and a 14 TBq ¹³⁷Cs gamma source to simulate the HL-LHC environment. The amplified analog signals of the chamber have been read out by 32 channels of high speed digitizer, permitting to study in details the various aspects of the detector physics in different condition of gamma background and field applied in the gas. Analysis methods and results of these data will be presented, illustrating in details the most relevant features of this new detector: ~98% efficiency, 400 ps ~ 500 ps time resolution and ~0.1 cm spatial resolution, cross talk in between the singlets and cluster size.

The Compressed Baryonic Matter spectrometer (CBM) is a future fixed-target heavy-ion experiment located at the Facility for Anti-proton and Ion Research (FAIR) in Darmstadt, Germany. The key element in CBM providing hadron identification at incident beam energies between 2 and 11 AGeV (for Au-nuclei) will be a 120 m ² large Time-of-Flight (ToF) wall composed of Multi-gap Resistive Plate Chambers (MRPC) with a time resolution of the system better than 80 ps. Aiming for an interaction rate of 10 MHz for Au+Au collisions the MRPCs have to cope with an incident particle flux between 0.1 kHz/cm ² and 100 kHz/cm ² depending on their location. Being the system characterized by wide ranges of both granularity and rate capability, the conceptual design of the ToF-wall foresees 6 different granularities and 4 different detector designs. In order to elaborate the final MRPC design of these counters several heavy-ion in-beam and cosmic-ray tests were performed. In this contribution we present the conceptual design of the TOF wall and discuss the performance results of full-size MRPC prototypes.

The upcoming underground INO-ICAL experiment will be instrumented with 28,800 of RPCs (glass based electrode of 3 mm thick) of size (1.85× 1.74) m ², which are the active elements and the key goal of the ICAL is to precisely measure the neutrino(s) mass. The RPCs are operated in the avalanche mode, using a gas mixture of R134a (95.2%), I-Butane (4.5%) and SF ₆ (0.3%). The number of RPCs that would be used is large with a total volume of gas of ~ 200 m ³, a Closed Loop gas mixing System (CLS) is mandatory. The performance of the RPCs depends on various parameters namely, the environmental conditions such as atmospheric pressure, ambient temperature, humidity etc., flow rate of gas mixture into the RPCs, concentration of the gas mixture (should be maintained constant throughout the operation), quality of gas, the RPC input gas pressure, uniformity of conductive coating on the surface, uniform gas gap thickness, nozzle positions, electrode thickness, ageing etc. We have tried to achieve the optimum flow rate of gas mixture (few SCCM) into the RPCs in the CLS without deteriorating the performance of the RPC. A modest low flow rate is ideal due to the usage of glass as electrodes and low back ground radiation (low cosmic rays only) unlike CERN-CMS experiments where the electrodes used are of Bakelite and are operated under high radiations with flow rates of few litres per hour. In this paper we present the flow resistors that are fabricated (capillary) and are suitable for final ICAL RPCs, the primitive simulation studies done to understand the distribution of the flow of gas mixture inside an RPC and also the behaviour of gas flow with different position of the input gas nozzles of an RPC. We also conclude here with results of the safe operating pressure parameters required for the operation of ICAL RPC in the CLS.

The Compressed Baryonic Matter spectrometer (CBM) is expected to be operational in the year 2024 at the Facility for Anti-proton and Ion Research (FAIR) in Darmstadt, Germany. CBM aims to study strongly interacting matter under extreme conditions. The key element providing hadron identification is the Time-Of-Flight (TOF) wall at incident energies between 2 and 10 AGeV . The TOF-wall covers the polar angular range from 2.5 ^o–25 ^o and full azimuth. According to the simulation results, the TOF system is required to reach a time resolution of better than 80 ps for the particle identification (PID) under high rate. The existing conceptual design foresees a 120 m ² TOF-wall composed of Multi-gap Resistive Plate Chambers (MRPC) which is subdivided into a high rate region, a middle rate region and a low rate region. The flux in the low rate region is around 1 kHz/cm ². For this region, we developed a Multistrip-MRPC using thin float glass as the resistive electrode. In this paper, we present the design of these MRPC prototypes and the results obtained during the beam test at the E3 line at Beijing Electron-Positron Collider (BEPC).

The prototype Resistive Plate Chamber (RPC) has been made for the ATLAS phase II upgrade. The beam-test results showed that its cluster size is larger than expected. To figure out the causes, we developed a new approach in simulating RPC which based on Computer Simulation Technology (CST) Suite. The influences from the surface resistivity of the graphite layer and other characteristics have been studied. Comparisons between the simulation data and the beam-tests results have also been performed.

The Multigap Resistive Plate Chambers (MRPCs) provide excellent timing as well as position resolutions at relatively low cost. Therefore, they can be used in medical imaging applications such as PET where precise timing is a crucial parameter of measurement. We have designed and fabricated several six-gap glass MRPCs and extensively studied their performance. In this paper, we describe the detector, the electronics and the data acquisition system of the setup. We present here the data analysis procedure and initial results of our studies to measure the absolute position of a radioactive source ( ²²Na) using Time Of Flight (TOF) as well as the hit coordinate information and hence to demonstrate their potential applications in medical imaging. We also present the geant4 based simulation results on the efficiency of our detector as a function of the number of gaps and converter material thickness.

For precise start time determination a Beam Fragmentation T ₀ Counter (BFTC) is under development for the Time-of-Flight Wall of the Compressed Baryonic Matter Spectrometer (CBM) at the Facility for Antiproton and Ion Research (FAIR) at Darmstadt/Germany. This detector will be located around the beam pipe, covering the front area of the Projectile Spectator Detector. The fluxes at this region are expected to exceed 10 ⁵cm ⁻²s ⁻¹. Resistive plate chambers (RPC) with ceramic composite electrodes could be use because of their high rate capabilities and radiation hardness of material. Efficiency ≥ 97 %, time resolution ≤ 90 ps and rate capability ≥ 10 ⁵cm ⁻²s ⁻¹ were confirmed during many tests with high beam fluxes of relativistic electrons. We confirm the stability of these characteristics with low resistive Si ₃N ₄/SiC floating electrodes for a prototype of eight small RPCs, where each of them contains six gas gaps. The active RPC size amounts 20×20 mm ² produced on basis of Al ₃O ₂ and Si ₃N ₄/SiC ceramics. Recent test results obtained with relativistic electrons at the linear accelerator ELBE of the Helmholtz-Zentrum Dresden-Rossendorf with new PADI-10 Front-end electronic will be presented.

Resistive Plate Chamber (RPC) detectors are widely employed in the muon trigger systems of three experiments at the CERN Large Hadron Collider (LHC) thanks to their excellent time resolution. The LHC RPC systems are operated under gas recirculation to reduce operation cost and greenhouse gas emissions since their gas mixture is based on C ₂H ₂F ₄, which has a global warning potential of 1430 and it is subject to the European F-gas Regulation. Extensive gas analysis campaigns have been performed during LHC Run 2 for the CMS RPC and ALICE Muon Trigger (MTR) systems to verify the gas mixture quality and possible accumulation of impurities. A particular attention has been addressed to the ALICE MTR system, which has been operated under gas recirculation from the end of 2015. In order to validate the system ensuring good detector operation, the gas recirculation has been increased in steps: 30%, 60% and 70%. Detector currents and gas mixture quality have been closely monitored. A gas chromatograph and mass spectrometer (GC/MS) station has been installed to analyze the MTR gas mixture in different points of the gas system: fresh gas from the mixer, detectors output and output of the purifier module. Several impurities have been found and identified. Most of the impurities are created inside the detector gas gap due to the fragmentation of the C ₂H ₂F ₄ molecule under the effects of electric field and radiation. The GC/MS analyses have been regularly performed in 2016 and 2017. It has been demonstrated that impurities concentration (at the level of tens of ppm) increases with the increase of the gas recirculation fraction. GC/MS analyses have been also performed after the purifier module showing that some impurities are filtered while others not. In parallel, the RPC currents have been constantly monitored, and their trend showed no correlation with the gas recirculation fraction. In 2017 an Ion Selective Electrode station was installed to measure the fluoride ions (F ⁻) concentration in the MTR RPC gas mixture. Indeed the products of the C ₂H ₂F ₄ fragmentation not always recombine and F^− species can stay free in the gas mixture. The analyses show that F ⁻ are present in the mixture exiting the RPCs and their concentration increases with the increase of luminosity, even if it stays at the level of ppb per day. A comprehensive overview of the results obtained from the different types of gas analyses and possible correlation with RPC currents and LHC luminosity will be presented.

The gas mixture for the Resistive Plate Chambers (RPCs), used for the Muon Spectrometer of the ALICE experiment at CERN LHC, is made up of C ₂ H ₂ F ₄, SF ₆ and iC ₄ H ₁₀. Since the first two gases have high Global Warming Potentials (GWPs), they will be phased out of production in the next years due to the recent European Union regulations; meanwhile their cost is progressively increasing. Therefore, finding a new eco-friendly gas mixture has become extremely important. In order to identify a gas mixture suited to cope with the requirements of the ALICE Muon Identifier in the forthcoming High-Luminosity runs, R&D studies have been performed on promising gas mixtures with small-size RPCs. Hydrofluoroolefins ( HFOs) may substitute C ₂ H ₂ F ₄ thanks to their very low GWPs, especially HFO1234 ze. Several tests on HFO-based mixtures are ongoing and encouraging results have already been obtained. Furthermore, the use of CO ₂ as a quencher has been studied, along with medium-term stability of detectors exposed to the cosmic-ray flux.

The Extreme Energy Events observatory is an extended muon telescope array, covering more than 10 degrees both in latitude and longitude. Its 59 muon telescopes are equipped with tracking detectors based on Multigap Resistive Plate Chamber technology with time resolution of the order of a few hundred picoseconds. The recent restrictions on greenhouse gases demand studies for new gas mixtures in compliance with the relative requirements. Tetrafluoropropene is one of the candidates for tetrafluoroethane substitution, since it is characterized by a Global Warming Potential around 300 times lower than the gas mixtures used up to now. Several mixtures have been tested, measuring efficiency curves, charge distributions, streamer fractions and time resolutions. Results are presented for the whole set of mixtures and operating conditions, focusing on identifying a mixture with good performance at the low rates typical of an EEE telescope.

The present paper is meant as an update of the presentation given in a previous Resistive Plate Chamber (RPC) workshop, aimed at finding an eco-friendly gas mixture for streamer operation of RPCs. Indeed the streamer working regime is still suitable for building large RPC systems dedicated to low rate applications, such as cosmic ray and neutrino physics. In addition to other studies about gas mixtures for streamer mode operation, in this paper the replacement of R134a with CF ₄, a gas widely used in other gaseous detectors, has been investigated. The effect of the gas gap thickness on the discharge quenching has also been studied; this is an important check because thin gas gaps of 1 mm, one half of the typical used value, have been introduced for high rate applications. Finally preliminar results about the streamer formation timing are also reported.

The Extreme Energy Events (EEE) experiment is the largest system in the world completely implemented with Multigap Resistive Plate Chambers (MRPCs). Presently, it consists of a network of 59 muon telescopes, each made of 3 MRPCs, devoted to the study of secondary cosmic rays. Its stations, sometimes hundreds of kilometers apart, are synchronized at a few nanoseconds level via a clock signal delivered by the Global Positioning System. The data collected during centrally coordinated runs are sent to INFN CNAF, the largest center for scientific computing in Italy, where they are reconstructed and made available for analysis. Thanks to the on-line monitoring and data transmission, EEE operates as a single coordinated system spread over an area of about 3 × 10 ⁵ km ². In 2017, the EEE collaboration started an important upgrade program, aiming to extend the network with 20 additional stations, with the option to have more in the future. This implies the construction, testing and commissioning of 60 chambers, for a total detector surface of around 80 m ². In this paper, aspects related to this challenging endeavor are covered, starting from the technological solutions chosen to build these state-of-the-art detectors, to the quality controls and the performance tests carried on.

We plan to build an imaging setup for material identification utilizing the Coulomb scattering of cosmic ray muons due to their interaction with the materials and tracking their trajectories with Resistive Plate Chambers (RPCs). To begin with, we consider a setup of six RPCs stacked in a parallel manner to read the position and timing information of the muons before and after their interaction with a phantom of a given material using a set of three RPCs for each phase. Here we present a simulation work carried out to study the image formation of phantoms of several materials. A detailed modeling of the imaging system consisting of six RPCs was done using GEANT4. Cosmic Ray Library (CRY) was used for generation of particles with the appropriate energy and zenith angle distribution. Three reconstruction algorithms were followed for material identification and image reconstruction, viz. Point of Closest Approach (POCA), Iterative POCA and the Binned Cluster Algorithm. A weighted metric discriminator was calculated for target object identification. Using the algorithms, the imaging of the Region of Interest (ROI) lying between the two layers of RPCs was done. The time required to discriminate target objects and do the image reconstruction has been studied.

Multi-gap Resistive Plate Chamber (MRPC) is a widely used timing detector with a typical time resolution of about 60 ps. This makes MRPC an optimal choice for the time of flight (ToF) system in many large physics experiments. The prior work on improving the time resolution is mainly focused on altering the detector geometry, and therefore the improvement of the data analysis algorithm has not been fully explored. This paper proposes a new time reconstruction algorithm based on the deep neural networks (NN) and improves the MRPC time resolution by about 10 ps. Since the development of the high energy physics experiments has pushed the timing requirements for the MRPC to a higher level, this algorithm could become a potential substitution of the time over threshold (ToT) method to achieve a time resolution below 30 ps.

Large area arrays composed by dispersed stations are of major importance in experiments where Extensive Air Shower (EAS) sampling is necessary. In those dispersed stations, detectors that require very low maintenance and show good resilience to environmental conditions are mandatory. In 2012, our group started to work in Resistive Plate Chambers that could become acceptable candidates to operate within these conditions. Since that time, more than 30 complete detectors were produced, tested and installed in different places, both indoor and outdoor. The data and analysis presented here are mainly related to the tests made in the Auger site in real conditions, where two Resistive Plate Chambers have been under test for more than two years. The results confirm the capability to operate such kind of Resistive Plate Chambers for long time periods under harsh conditions at a stable efficiency. In the last years, Laborat&apos;{o}rio de Instrumentação e F&apos;{i}sica Experimental de Part&apos;{i}culas and USP—São Carlos have led a collaboration with the aim of installing an Engineering Array at BATATA (Auger) site to learn in more detail and improve the resilience and performance of the Resistive Plate Chambers in outdoor conditions. The organization of such collaboration and the work done so far will be presented.

The ALICE Time-Of-Flight (TOF) detector at LHC is based on the Multigap Resistive Plate Chambers (MRPCs). The TOF performance during LHC Run 2 is here reported. Particular attention is given to the improved time resolution reached by TOF detector of 56 ps, with the consequently improved particle identification capabilities.

With the upgrade of the RPCs [1,2] and the increase of its performance, the study and the optimization of the read-out panel is necessary in order to maintain the signal integrity and to reduce the intrinsic crosstalk. Through Electromagnetic Simulation, performed with CST Studio Suite, new panels design are tested and their crosstalk properties are studied. The behavior of different type of panel is shown.

TOF (Time Of Flight) system based on MRPC (Multi-gap Resistive Plate Chamber) technology is widely used in modern physics experiments, and it also plays an important role in particle identification. With the increase of accelerator energy and luminosity, the TOF system is required to identify definite particles precisely under high rate environment. The MRPC technology TOF system can be defined as three generations. The first generation TOF is based on float glass MRPC and its time resolution is around 80 ps, but the rate is relatively low (typically lower than a few hundred Hz/cm ²). The typical systems are TOF of RHIC-STAR, LHC-ALICE and BES III endcap. For the second generation TOF, its time resolution is in the same order with the first generation, but the rate capability is much higher. Its rate capability can reach 30 kHz/cm ². The typical experiment with this high rate TOF is FAIR-CBM. The biggest challenge is on the third generation TOF. For example, the momentum upper limit of K/PI separation is around 7 GeV/c for JLab-SoLID TOF system under high particle rate as high as 20 kHz/cm ², the time requirement is around 20 ps. The readout electronics of the first two generations is based on time over threshold method and pulse shape sampling technology will be used in the third generation TOF. In the same time, the machine learning technology is also designed to analyze the time performance. In this paper, we will describe the evolution of MRPC TOF technology and key technology of each generation TOF.

The Compressed Baryonic Matter (CBM) spectrometer aims to study strongly interacting matter under extreme conditions. The key element providing hadron identification at incident energies between 2 and 11AGeV in heavy-ion collisions at the SIS100 accelerator is a Time-of-Flight (TOF) wall covering the polar angular range from 2.5 ^o–25 ^o and full azimuth. CBM is expected to be operational in the year 2024 at the Facility for Anti-proton and Ion Research (FAIR) in Darmstadt, Germany. The existing conceptual design foresees a 120 m ² TOF-wall composed of Multi-gap Resistive Plate Chambers (MRPC) which is subdivided into a high rate region, a middle rate region and a low rate region. The MRPC3b Multistrip-MRPCs, foreseen to be integrated in the low rate region, have to cope with charged particle fluxes up to 1 kHz/cm ² and therefore will be constructed with thin float glass (0.28 mm thickness) as resistive electrode material. In the scope of the FAIR phase 0 program it is planned to install about 36% of the MRPC3b counters in the east endcap region of the STAR experiment at BNL as an upgrade for the Beam Energy Scan campaign (BESII) in 2019/2020.

Muon tomography system built by 2-D readout high spatial resolution Multi-gap Resistive Plate Chamber (MRPC) detector is a project in Tsinghua University. In 2013, we had developed a prototype of muon tomography system named TUMUTY, now we try to develop larger sensitive area and smarter structure MRPC detector to upgrade the system to a car detection system, which is used to detect high Z metal hidden in cars or other objects. For the system, 2 layers × 3 detectors are needed to get the incident particle's track, and the setting is the same for the outgoing track. Therefore, there will four layers containing twelve detectors in total, and its detection area will reach 1× 3 m ². An encoding readout method is suggested to minimize the number of the readout electronics, which reduces the complexity and the cost of the system. In this paper, we measured the performance of 12 MRPCs used for the system.

The ALICE Muon Trigger is currently yielded by a detector composed of 72 Bakelite single-gap Resistive Plate Chambers operated in maxi-avalanche mode, arranged in four 5.5×6.5 m ² detection planes. In order to meet the requirements posed by the forthcoming LHC high luminosity runs starting from 2021 onwards, in which ALICE will be read out in continuous mode, the Muon Trigger will become a Muon Identifier and will undergo a major upgrade. In the current setup, signals from about 21 k strips are discriminated by 2400 non-amplified Front End (FEE) cards, whose thresholds are provided by external analog voltages (one for each chamber side). All these cards will be replaced with discriminators equipped with a pre-amplification stage which will allow a reduction in the operating high voltage of the detectors, thus prolonging their lifetime. Furthermore, their reference thresholds will be passed via wireless (and I2C chained per chamber side) allowing the tuning of the values at the single card level. Moreover, the 24 most exposed chambers will be replaced with new ones, equipped with high-quality (i.e. smoother surface) Bakelite laminates. The tests performed on the new FEE cards, used both in a test bench and on detectors, and on the new RPC chambers (with cosmic rays) are reported.

The Multi-gap Resistive Plate Chamber (MRPC) is an upgraded version of Resistive Plate Chamber (RPC) with excellent time resolution. They have found suitable applications in several High Energy Physics (HEP) experiments and also in medical physics like Positron Emission Tomography (PET) imaging. We have successfully developed and tested with cosmic rays a prototype MRPC using bakelite sheets without any oil treatment. In this document, we report the cosmic ray test performance of the second similar prototype. This effort is towards the development of a prototype set-up for PET imaging in Medical Imaging Laboratory at Variable Energy Cyclotron Centre, Kolkata, India.

The discovery of the Higgs boson has fully confirmed the Standard Model of particles and fields. Nevertheless, there are still fundamental phenomena, like the existence of dark matter and the baryon asymmetry of the Universe, which deserve an explanation that could come from the discovery of new particles. The SHiP experiment at CERN meant to search for very weakly coupled particles in the few GeV mass domain has been recently proposed. The existence of such particles, foreseen in Beyond Standard Models, is largely unexplored. A beam dump facility using high intensity 400 GeV protons is a copious source of such unknown particles in the GeV mass range. The beam dump is also a copious source of neutrinos and in particular it is an ideal source of tau neutrinos, the less known particle in the Standard Model. We report the physics potential of such an experiment and describe the use of the RPC technology therein. An anchillary measurement of the charm cross-section will be carried out in July 2018 and RPC are used as a muon detector. We also describe the design and construction of these new chambers.

The Compressed Baryonic Matter (CBM) experiment will be one of the major scientific pillars of the future Facility for Antiproton and Ion Research (FAIR) in Darmstadt. The Multigap Resistive Plate Chamber (MRPC) has been adopted for the construction of the Time of Flight (TOF) Wall; a system time resolution of 80ps is necessary for hadron identification. MRPC3b, as defined in the CBM TOF TDR, has been designed for the outer region of the TOF system. The MRPC3b is a two-stack, 10 gas gaps with 32 strips read out at both ends. The thin floating glass will be used as the electrodes. In this paper, the design details will be discussed. The mass production has already during the spring of 2017. The assembly procedures and QA (Quality Assurance) & QC (Quality Control) methods will also be presented. The performance achieved from the cosmic ray test shows that the efficiency is better than 91% and the resolution is about 80ps with 95% Freon and 5% iso-butane gas mixture.

The first level (Level-1) muon barrel trigger is one of the main elements of the event selection of the ATLAS experiment at the Large Hadron Collider. Its input is made of an array of processors which receive the full granularity of data from Resistive Plate Chambers (RPC) in the central ("Barrel") area of the ATLAS detector. The Barrel RPCs are arranged in three concentric shells and operate in a strong toroidal magnetic field. The RPC detectors cover the pseudo-rapidity range  | η |< 1.05 for a total surface of more than 4000 m ² and about 3600 gas volumes. The Level-1 Muon Trigger in the barrel region allows to select muon candidates with respect to their transverse momentum providing also the bunch-crossing assignment. We present the performance of the Level-1 muon trigger during the LHC Run-2 data taking, in particular for the years 2015–2017.

The experiments at the Large Hadron Collider operate in a large radiation background. In the perspective of the future increase of the luminosity, estimates of the signal rate caused by neutral radiation (gamma rays and neutrons) coming from collisions in the beam-pipe material, magnets, or from the activation of materials in the experimental area, must be assessed, in order to determine the signal rate per unit area, as this is one of the main parameters that could affect the proper functioning of the RPCs. We describe preliminary results of a GEANT4 simulation to assess the ATLAS-like double-gap RPC chamber sensitivity to gamma rays and neutrons.

The muon telescopes of the Extreme Energy Events (EEE) Project [1] are made of three Multigap Resistive Plate Chambers (MRPC). The EEE array is composed, so far, of 59 telescopes and is organized in clusters and single telescope stations distributed all over the Italian territory. They are installed in High Schools with the aim to join research and teaching activities, by involving researchers, teachers and students in the construction, maintenance, data taking and data analysis. The unconventional working sites, mainly school buildings with non-controlled environmental parameters and heterogeneous maintenance conditions, are a unique test field for checking the robustness, the low-ageing features and the long-lasting performance of the MRPC technology for particle tracking and timing purposes. The measurements performed with the EEE array require excellent performance in terms of time and spatial resolution, efficiency, tracking capability and stability. The data from two recent coordinated data taking periods, named Run 2 and Run 3, have been used to measure these quantities and the results are described, together with a comparison with expectations and with the results from a beam test performed in 2006 at CERN.

In the quest for particle dark matter and physics beyond the Standard Model, the possibility of the existence of neutral long-lived particles (LLPs) has been proposed. The MATHUSLA project has been designed to detect possible LLPs produced in LHC collisions with a surface detector built by exploiting existing technologies. The detector will be installed above one of the high-luminosity interaction regions of the LHC before the beginning of the Phase-2 operation. A small-scale MATHUSLA test detector implemented with two stations of scintillators from the D0 experiment and three stations of Resistive Plate Chambers originally designed for the ARGO experiment was installed and operated above the ATLAS interaction point in November 2017. Each RPC station consisted of two detector layers, about 7 m ² each, with orthogonal read-out strips. The results of the test run will be presented.

In the next decades, the Large Hadron Collider (LHC) will run at very high luminosity (HL-LHC) 5×10 ³⁴ cm ⁻²s ⁻¹, factor five more than the nominal LHC luminosity. During this period the CMS RPC system will be subjected to high background rates which could affect the performance by inducing aging effects. A dedicated longevity program to qualify the present RPC system for the HL-LHC running period is ongoing. At the CERN Gamma Irradiation Facility (GIF++) four RPC detectors, from the spare production, are exposed to an intense gamma radiation for a dose equivalent to the one expected at the HL-LHC . The main detector parameters are under monitoring as a function of the integrated charge and the performance is studied with a muon beam. Preliminary results of the study after having collected ≈ 34% of the expected integrated charge will be presented.

With the increase of the LHC luminosity foreseen in the coming years, many detectors currently used in the different LHC experiments will be dramatically impacted and some need to be replaced or upgraded. The new ones should be capable to provide time information to reduce the data ambiguity due to the expected high pileup. We propose to equip CMS high |η| muon chambers with pairs of single gap RPC detectors read out by long pickup strips PCB. The precise time measurement (0<15 ps) of the signal induced by particles crossing the detector on both ends of each strip will give an accurate measurement of the position of the incoming particle along the strip. The absolute time measurement, determined by RPC signal (around 1.5 ns) will also reduce the data ambiguity due to the highly expected pileup and help to identify Heavy Stable Charged Particles (HSCP). The development of a specific electronic chain (analog front-end ASIC, time-to-digital converter stage and printed circuit board design) and the corresponding first results on prototype chambers are presented.