Search

The current operation of the Resistive Plate Chamber (RPC) system within the CMS experiment involves approximately 95% tetrafluoroethane (C 2 H 2 F 4 , TFE). However, in response to climate change concerns, the European Union has instituted a ban on TFE owing to its elevated Global Warming Potential (GWP), resulting in an associated increase in market prices. In this framework, shared endeavors within the RPC EcoGas@GIF++ Collaboration, have been dedicated to investigating novel ecological gaseous mixtures based on tetrafluoropropene (C 3 H 2 F 4 , HFO-1234ze) to ensure the sustainable functionality of RPCs. This presentation will delve into the performance outcomes derived from improved RPC gas gaps operating on HFO/CO 2 -based mixtures as ecologically viable alternatives, particularly in anticipation of the High Luminosity LHC phase (HL-LHC). Additionally, the utilization of TFE/CO 2 mixtures will be explored as a pragmatic strategy to swiftly alleviate gas-related operational costs. [ABSTRACT FROM AUTHOR]

In anticipation of the High Luminosity LHC, an extensive upgrade is underway for the CMS Muon system to ensure its optimal performance in muon triggering and reconstruction. The indispensable role of Resistive Plate Chambers (RPC) as dedicated muon detectors stems from their exceptional timing resolution. To meet the requirements of Phase-II of the LHC, the RPC system will be expanded up to a pseudorapidity of 2.4. The forward Muon system's upcoming RE3/1 and RE4/1 stations will feature improved Resistive Plate Chambers (iRPC). Distinguished by a unique design and geometry, including a 2D strip readout, these iRPCs represent a significant advancement over the current RPC system. The enhancements include the use of thinner electrodes, a narrower 1.4 mm gas gap, and improved Front-End Board (FEB) allowing a 30 fC threshold. Two iRPC chambers were installed in station 3 of CMS during the year end technical stop (YETS) 2023/2024 and other 70 are being assembled at CERN and being prepared for installation next YETS 2024/2025. This paper provides a comprehensive summary of quality control (QC) and future plans for iRPC chambers in CMS detector. [ABSTRACT FROM AUTHOR]

A new readout technique was developed with the primary aim of keeping the number of channels in the front-end electronics as low as possible when scaling up the sensitive area of a Resistive Plate Chamber (RPC). The readout method here presented significantly reduces the dependence between the detector area and the number of electronic channels, without substantial reduction of its performance: a 30 × 30 cm 2 double stack multi-gap timing RPC was operated during weeks with cosmic rays, achieving a 2D spatial resolution well below 1 mm and time resolution lower than 100 ps, while its efficiency was kept above 98%. [ABSTRACT FROM AUTHOR]

The ALICE Muon IDentifier is composed of 72 single-gap bakelite Resistive Plate Chambers, which have been operational since 2009 in avalanche mode with a Tetrafluoroethane/Isobutane/Sulphur Hexafluoride gas mixture, undergoing counting rates of the order of tens of Hz/cm 2. Here, the long-term performance and stability of the RPC system will be discussed, in terms of efficiency, dark current and dark rate. An assessment of potential signs of ageing observed in the detectors will be presented, together with a summary of the most common hardware problems experienced. [ABSTRACT FROM AUTHOR]

Resistive Plate Chambers (RPCs) are gaseous detectors widely used in high energy physics experiments, operating with a gas mixture primarily containing Tetrafluoroethane (C 2 H 2 F 4), commonly known as R-134a, which has a global warming potential (GWP) of 1430. To comply with European regulations, the RPC EcoGas@GIF++ collaboration, involving ALICE, ATLAS, CMS, LHCb/SHiP, and EP-DT communities, has undertaken intensive R&D efforts to explore new environmentally friendly alternative gas mixtures for RPC technology. A leading alternative under investigation is HFO1234ze, boasting a low GWP of 6 and demonstrating reasonable performance compared to R-134a. Over the past few years, RPC detectors with slightly different characteristics and electronics have been studied using HFO and CO 2 -based gas mixtures at the CERN Gamma Irradiation Facility. An aging test campaign was launched in August 2022, and during the latest test beam in July 2023, all detector systems underwent evaluation. This contribution will report the results of the aging studies and the performance evaluations of the detectors with and without irradiation. [ABSTRACT FROM AUTHOR]

ALICE (A Large Ion Collider Experiment) studies the Quark-Gluon Plasma (QGP): a deconfined state of nuclear matter obtained in ultra-relativistic heavy-ion collisions. One of the key probes for QGP characterization is the study of quarkonia and open heavy flavor production, of which ALICE exploits the muonic decay. In particular, a set of Resistive Plate Chambers (RPCs), placed in the forward rapidity region of the ALICE detector, is used for muon identification purposes. The correct operation of these detectors is ensured by the choice of the proper gas mixture. Currently they are operated with a mixture of C 2 H 2 F 4 , i-C 4 H 10 and SF 6 but, starting from 2017, new EU regulations have enforced a progressive phase-out of C 2 H 2 F 4 because of its large Global Warming Potential (GWP), which is making it difficult and costly to purchase. Moreover, CERN asked LHC experiments to reduce greenhouse gases emissions, to which RPC operation contributes significantly. A possible candidate for C 2 H 2 F 4 replacement is the C 3 H 2 F 4 (diluted with other gases, such as CO 2), which has been extensively tested using cosmic muons. Promising gas mixtures have been devised; the next crucial steps are the detailed in-beam characterization of such mixtures as well as the study of their performance under increasing irradiation levels. This contribution will describe the methodology and results of beam tests carried out at the CERN Gamma Irradiation Facility (equipped with a high activity 137Cs source and muon beam) with an ALICE-like RPC prototype, operated with several mixtures with varying proportions of CO 2 , C 3 H 2 F 4 , i-C 4 H 10 and SF 6. Absorbed currents, efficiencies, prompt charges, cluster sizes, time resolutions and rate capabilities will be presented, both from digitized (for detailed shape and charge analysis) and discriminated (using the same front-end electronics as employed in ALICE) signals. [ABSTRACT FROM AUTHOR]

Resistive Plate Chambers (RPCs) are a key active media of the muon systems of current and future collider experiments as well as the CALICE (semi-)digital hadron calorimeter. The outstanding issues with RPCs can be listed as the loss of efficiency for the detection of particles when subjected to high particle fluxes and the limitations associated with the common RPC gases. We developed novel RPC designs with: low resistivity glass plates; a single resistive plate; and a single resistive plate and a special anode plate coated with high secondary electron emission yield material. The cosmic and beam tests confirmed the viability of these new approaches for calorimetric applications. The chambers also have improved single-particle response, such as a pad multiplicity close to unity. Here, we report on the construction of various different glass RPC designs and their performance measurements in laboratory tests and with particle beams. We also discuss future test plans, which include the long-term performance tests of the newly developed RPCs, investigation of minimal gas flow chambers, and feasibility study for the large-size chambers. [ABSTRACT FROM AUTHOR]

The standard gas mixture for the Resistive Plate Chambers (RPC), composed of C 2 H 2 F 4 /i- C 4 H 10 / SF 6 , allows the detector operation in avalanche mode, as required by the high-luminosity collider experiments. The C 2 H 2 F 4 and SF 6 are now considered to be non-eco-friendly gases for their high Global Warming Potential (GWP). These gases are not recommended for industrial uses anymore, thus their availability will be increasingly difficult over time and the search for an alternative gas mixture is then of absolute priority. There are several studies on going which use different approach to find an alternative gas mixture suitable for experiment which work in high-radiation environment, as those operating at the Large Hadron Collider (LHC). One approach is to replace the standard gas with HFO1234ze/ CO 2 /i- C 4 H 10 / SF 6 , being the HFO1234ze/ CO 2 the main gas component and obtaining a gas mixture with a GWP ∼ 200. The second approach, currently under study by ATLAS and CMS collaborations, is to introduce a small fraction of CO 2 in the standard gas mixture, thus reducing the emissions of C 2 H 2 F 4 . In this presentation the results on the performance achieved using a 1 mm gas gap RPC with both types of gas mixtures are reported. Moreover, the possibility to reduce the SF 6 fraction and to replace it at all with a new gas, the HFO1233zd, is also reported. The RPC performance are studied under strong photon irradiation which reproduces the gamma background of the ATLAS cavern and that expected during the High-Luminosity phase of the LHC. [ABSTRACT FROM AUTHOR]

A novel type of resistive plate chamber, based on diamond-like carbon (DLC) electrodes is under development for background identification in the MEG II experiment. The DLC-RPC is required to have a radiation hardness to mass irradiation since it is planned to be placed in a high-intensity and low-momentum muon beam. In this study, the aging test using a high-intensity X-ray beam was conducted to evaluate the radiation hardness of the DLC-RPC. The accumulated charge due to X-ray irradiation reached about 54 C/ cm 2 , which is approximately half of the one-year irradiation dose expected in the MEG II experiment. As a result, the degradation of the gas gain was observed due to fluorine deposition and insulators formed on the DLC electrodes. In addition, discharges via spacers were also observed repeatedly and interrupted the DLC-RPC operation. [ABSTRACT FROM AUTHOR]

In view of the High Luminosity upgrade of the CERN LHC, the forward CMS Muon spectrometer will be extended with two new stations of improved Resistive Plate Chambers (iRPC) covering the pseudorapidity range from 1.8 to 2.4. Compared to the present RPC system, the gap thickness is reduced to lower the avalanche charge, and an innovative 2D strip readout geometry is proposed. These improvements will allow iRPC detector to cope with higher background rates. A new Front-End-Board (FEB) is designed to readout iRPC signals with a threshold as low as 30 fC and an integrated Time Digital Converter with a resolution of 30 ps. In addition, the communication bandwidth is significantly increased by using optical fibers. The history, final design, certification, and calibration of this FEB are presented. [ABSTRACT FROM AUTHOR]

An efficient and safe gas mixture recirculation system for Resistive Plate Chambers (RPCs) detector is a crucial item for planning any future application. The system is based on a special valve that decouples a suction pump from the RPC, with the aim to keep the pressure inside the chamber in the range from 1 mbar to 3 mbar, regardless of variations in atmospheric pressure, recirculated flow, and temperature. The circulating gas is flushed in pure water where the impurities developed inside the detector are expected to be soluble and trapped. [ABSTRACT FROM AUTHOR]

Resistive Plate Chambers (RPCs) are a key active media of the muon systems of current and future collider experiments as well as the CALICE (semi-)digital hadron calorimeter. The outstanding issues with RPCs can be listed as the loss of efficiency for the detection of particles when subjected to high particle fluxes and the limitations associated with the common RPC gases. We developed novel RPC designs with: low resistivity glass plates; a single resistive plate; and a single resistive plate and a special anode plate coated with high secondary electron emission yield material. The cosmic and beam tests confirmed the viability of these new approaches for calorimetric applications. The chambers also have improved single-particle response, such as a pad multiplicity close to unity. Here, we report on the construction of various different glass RPC designs and their performance measurements in laboratory tests and with particle beams. We also discuss future test plans, which include the long-term performance tests of the newly developed RPCs, investigation of minimal gas flow chambers, and feasibility study for the large-size chambers.

In view of the High Luminosity LHC, the CMS Muon system will be upgraded to sustain its efficient muon triggering and reconstruction performance. Resistive Plate Chambers (RPC) are dedicated detectors for muon triggering due to their excellent timing resolution. The RPC system will be extended up to 2.4 in pseudorapidity. Before the LHC Long Shutdown 3, new RE3/1 and RE4/1 stations of the forward Muon system will be equipped with improved Resistive Plate Chambers (iRPC) having, compared to the present RPC system, a different design and geometry and 2D strip readout. This advanced iRPC geometry configuration allows the rate capability to improve and hence survive the harsh background conditions during the HL-LHC phase. Several iRPC demonstrator chambers were installed in CMS during the recently completed 2nd Long Shutdown to study the detector behaviour under real LHC conditions. This paper summarizes the iRPC project and its schedule, including the status of the iRPC production sites, details of the chamber quality control procedures and results of the commissioning of the demonstrator chambers. [ABSTRACT FROM AUTHOR]

Muon tomography is one of several fields of applied physics that have witnessed the successful use of particle detection based on Resistive Plate Chambers (RPC). In this work, we report on an innovative project concerning transmission muography for geological characterization. For this purpose, a muon telescope built of four RPC planes was mounted on an adjustable structure and the telescope's response to atmospheric muons was studied. Data acquisition campaigns took place at different locations for producing muographic images of the building of the Physics Department of the University of Coimbra, in Portugal. More recently, the detector was moved to an underground gallery of an old mine, where it is taking data that is being assessed in combination with the results from conventional geophysics techniques. [ABSTRACT FROM AUTHOR]

The standard gas mixture for the Resistive Plate Chambers (RPC), composed of C 2 H 2 F 4 /i- C 4 H 10 / SF 6 , allows the detector operation in avalanche mode, as required by the high-luminosity collider experiments. The gas density, the low total charge delivered inside the gas and the comfortable avalanche-streamer separation guarantee high detection efficiency, rate capability and slow detector aging. The standard RPC gas mixture is mostly based on Hydrofluorocarbons, HFCs, extensively used in the refrigeration industry. The Hydrofluorocarbons are now considered to be non-eco-friendly gases for their high Global Warming Potential (GWP). The SF 6 has the largest GWP, 22 900, but, due to its low concentration, it contributes only with few tens of units to the total value. The major contribution comes from the main standard gas mixture component, the C 2 H 2 F 4 (GWP ≈ 1300). These gases are not recommended for industrial uses anymore, thus their availability will be increasingly difficult over time and the search for an alternative gas mixture with low-GWP is then of absolute priority within the RPC community. We report the performance of the RPC working with new environment-friendly gases which could replace the standard mixture. In this work the standard mixture main component, the C 2 H 2 F 4 , is replaced by a proper mixture of CO 2 (GWP = 1) and Tetrafluoropropene ( C 3 H 2 F 4 , GWP ≈ 6). The other high-GWP component, the SF 6 , is replaced by a molecule, the Chloro-Trifluoropropene ( C 3 H 2 ClF 3 , GWP ≈ 5) never tested in RPC detectors. The mixtures studied have a total GWP ≈ 10. We report, for several eco-gas mixtures, the detection efficiency, streamer probability, electronic and ionic charge as a function of the high voltage. Moreover, the timing properties are studied and the detector time resolution is measured. We also focus the attention on a new category of signals having intermediate properties between avalanche and streamer, called "transition events". This category is negligible for the standard gas mixture but relevant for HFO/ CO 2 -based gas mixtures. We show a direct comparison between SF 6 and C 3 H 2 ClF 3 to study in depth the possibility to replace the SF 6. [ABSTRACT FROM AUTHOR]

A new generation of gaseous particle detectors named Resistive Cylindrical Chamber (RCC) (Cardarelli, 2021; Rocchi, 2022) [1,2] has been developed to overcome the limitations of Resistive Plate Chambers (Santonico and Cardarelli, 1981) [3] and broaden their application range. The principle behind this new technology consists in the transition from a planar to a cylindrical geometry while maintaining an almost planar electric field. The cylindrical structure of the electrodes allows to reach the following goals: increase the gas pressure to improve the intrinsic efficiency of the detector even for thin gas gaps or light gas mixtures; design the detector in order to produce an electric field gradient possibly useful to contain the development of the avalanche discharge. These features could lead to design detectors of simple mechanical realization with time resolution comparable with that of MRPCs maintaining a high efficiency of detection on a single thin gas-gap. The device pressurization could also allows to use new gases in view of the transition to eco-friendly gas. [ABSTRACT FROM AUTHOR]

Resistive Plate Chamber detectors are largely used in current High Energy Physics experiments, typically operated in avalanche mode with large fractions of Tetrafluoroethane (C2H2F4), a gas recently banned by the European Union due to its high Global Warming Potential (GWP). An intense R&D activity is ongoing to improve RPC technology in view of future HEP applications. In the last few years the RPC EcoGas@GIF++ Collaboration has been putting in place a joint effort between the ALICE, ATLAS, CMS, LHCb/SHiP and EP-DT Communities to investigate the performance of present and future RPC generations with eco-friendly gas mixtures. Detectors with different layout and electronics have been operated with ecological gas mixtures, with and without irradiation at the CERN Gamma Irradiation Facility (GIF++). Results of these performance studies together with plans for an aging test campaign are discussed in this article. [ABSTRACT FROM AUTHOR]

We present a study of the response of the highly granular Digital Hadronic Calorimeter with steel absorbers, the Fe-DHCAL, to positrons, muons, and pions with momenta ranging from 2 to 60 GeV/c. Developed in the context of the CALICE collaboration, this hadron calorimeter utilises Resistive Plate Chambers as active media, interspersed with steel absorber plates. With a transverse granularity of 1 × 1 cm2 and a longitudinal segmentation of 38 layers, the calorimeter counted 350,208 readout channels, each read out with single-bit resolution (digital readout). The data were recorded in the Fermilab test beam in 2010–11. The analysis includes measurements of the calorimeter response and the energy resolution to positrons and muons, as well as detailed studies of various shower shape quantities. The results are compared to simulations based on Geant4 , which utilise different electromagnetic and hadronic physics lists. [ABSTRACT FROM AUTHOR]

We report on the first steps in the development of a small-size muon telescope based on glass resistive plate chambers with small active area (16 × 16 cm²). The long-term goal of this project is to focus on applications of muography where the telescope may have to be operated underground and/or inside small rooms, and in challenging logistic situations. Driving principles in our design are therefore compact size, light weight, gas tightness and robustness. The first data-taking experiences have been encouraging, and we elaborate on the lessons learnt and future directions for development [ABSTRACT FROM AUTHOR]

We are developing time-of-flight (TOF) multi-gap Resistive Plate Chambers (MRPCs) which perform both timing and hit position measurements, the TOF-tracker MRPC, for muon detection to measure exclusive Drell–Yan reaction ( π − p → γ ∗ n → μ + μ − n) at J-PARC's hadron hall. Here we report on the development of a prototype TOF-tracker MRPC with a sensitive area of 500 × 1000 mm 2 and its performance in an electron-positron particle beam at the SPring-8 synchrotron in Japan. • Development of the muon detector for both timing and hit position measurements. • Beam test for examination of the basic performance the muon detector. • Achievement of a time resolution of 100 ps. [ABSTRACT FROM AUTHOR]

For the High Luminosity (HL-LHC) upgrade an upgrade of the CMS detector is foreseen. One of the main projects is the development of the improved Resistive Plate Chamber (iRPC) detectors that will be installed in the forward region of CMS. To validate the performance of the new detector gaps with HL-LHC radiation levels, experimental tests have been conducted at the CERN Gamma Irradiation Facility (GIF++). One chamber equipped with electronics is studied and its parameters are monitored as a function of the accumulated charge. [ABSTRACT FROM AUTHOR]

A known volume of air is injected into or aspirated from a sealed vessel. In the ideal gas approximation, the corresponding vessel deformation is measurable. The linear correlation between pressure and deformation in the measurements carried out demonstrates the vessel's elastic response. Measurements of several RPC gas volumes are reported. Different expansion and compression slopes of pressure vs volume plots, highlight a structure problem, for example, unglued spacers. Defective stiffness values of the electrode materials are also highlighted by anomalous slope values. [ABSTRACT FROM AUTHOR]

Resistive Plate Chambers (RPCs) are essential active media of large-scale experiments as part of the muon systems and (semi-)digital hadron calorimeters. Among the several outstanding issues associated with the RPCs, the loss of efficiency for the detection of particles when subjected to high particle fluxes, and the limitations associated with the common RPC gases can be listed. In order to address the latter issue, we developed novel RPC designs with special anode plates coated with high secondary electron emission yield materials such as Al 2 O 3 and TiO 2. The proof of principle was obtained for various designs and is in progress for the rest. The idea was initiated following the achievements on the development of the novel 1-glass RPCs. Here we report on the construction of various different RPC designs, and their performance measurements in laboratory tests and with particle beams; and discuss the future test plans. [ABSTRACT FROM AUTHOR]

The muon system of the CERN Compact Muon Solenoid (CMS) experiment includes more than a thousand Resistive Plate Chambers (RPC). They are gaseous detectors operated in the hostile environment of the CMS underground cavern on the Large Hadron Collider where pp luminosities of up to 2 × 1 0 34 cm − 2 s − 1 are routinely achieved. The CMS RPC system performance is constantly monitored and the detector is regularly maintained to ensure stable operation. The main monitorable characteristics are dark current, efficiency for muon detection, noise rate etc. Herein we describe an automated tool for CMS RPC current monitoring which uses Machine Learning techniques. We further elaborate on the dedicated generalized linear model proposed already and add autoencoder models for self-consistent predictions as well as hybrid models to allow for RPC current predictions in a distant future. [ABSTRACT FROM AUTHOR]

Thin-gap Resistive Plate Chambers (RPCs) with a 1 mm gap size are introduced in the ATLAS Phase-II upgrade. Smaller avalanche charge due to the reduced gap size raises concerns for signal integrity. This work focuses on the RPC signal propagation process in lossless conditions, and an analytical study is implemented for the ATLAS RPC. Detector modeling is presented, and the simulation of the RPC signal is discussed in detail. Simulated characteristic impedance and crosstalk have been compared with the measured value to validate this model. This method is applied to different RPC design geometries, including the newly proposed η − η readout scheme. [ABSTRACT FROM AUTHOR]

With the HL-LHC upgrade of the LHC machine, an increase of the instantaneous luminosity by a factor of five is expected and the current detection systems need to be validated for such working conditions to ensure stable data taking. At the CERN Gamma Irradiation Facility (GIF++) many muon detectors undergo such studies, but the high gamma background can pose a challenge to the muon trigger system which is exposed to many fake hits from the gamma background. A tracking system using RPCs is implemented to clean the fake hits, taking profit of the high muon efficiency of these chambers. This work will present the tracking system configuration, used detector analysis algorithm and results. [ABSTRACT FROM AUTHOR]

An optimized design of a neutron detector based on timing RPCs (Resistive Plate Chambers) with boron-10 neutron converters is presented. The detector is composed of a stack of ten double gap RPCs with aluminium cathode plates coated on both sides with 10B 4 C. This design enables simultaneous determination with high accuracy of both the neutron time-of-flight (down to ns resolution) and the interaction position in 3D (down to 0.25 mm resolution across and ∼ 1 mm along the beam). It is shown that the detection efficiency can approach 60% for neutrons with lambda = 4.7 Å. A new geometry with less material budget is introduced for the signal pick-up strip arrays. The results of simulation-based optimization of the design are reported considering the trade-off between the detection efficiency, the count rate capability and the amount of elastic scattering on the detector components. [ABSTRACT FROM AUTHOR]

Time resolution and efficiency of single-gap ( 300 μ m ) multi-strip timing resistive plate chambers (tRPC) have been investigated using 136 Xe ions accelerated at 560 A MeV with different rates. A time resolution of 37 ps (standard deviation) has been achieved for an irradiation rate of 12 Hz ∕ cm 2 . The tRPC also provides a detection efficiency above 98%. Our results show that an increase of the irradiation rate clearly leads to a degradation of the time resolution and a quenching of the signal charge. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In view of the High-Luminosity LHC (HL-LHC) phase, the Resistive Plate Chambers (RPC) system of the Compact Muon Solenoid (CMS) experiment will be extended by installing a new generation of improved-RPC. In the present study, a GEANT4 Monte Carlo simulation study has been done to estimate the background rate on the iRPCs expected in the future runs of HL-LHC. • CMS improved-RPC (iRPC) for the muon system upgrade. • GEANT4 simulation for the iRPC sensitivity study. • Estimation of the iRPCs background rate during HL-LHC. [ABSTRACT FROM AUTHOR]

Driven by the recent improvement in additive manufacturing technologies, we designed a detector that can be fully printed with a standard and commercial 3D printer. The main goals of this research concern the marginal design and construction costs, the reproducibility/modularity of the products, and the reduced assembly time. During the first phase of this research, after determining the most suitable material, we produced 10 examples of detector. [ABSTRACT FROM AUTHOR]