Resistive Plate Counters Research Articles

The surface Resistive Plate Counter (sRPC): an RPC based on MPGD technology

The Surface Resistive Plate Counter (sRPC) is a novel RPC based on surface resistivity electrodes, a completely different concept with respect to traditional RPCs that use electrodes characterised by volume resistivity. The electrodes of the sRPC exploit the well-established industrial Diamond-Like-Carbon (DLC) sputtering technology on thin (50 μm) polyimide foils, already introduced in the manufacturing of the resistive MPGDs such as μ-RWELL and MicroMegas, that allows to realise large area (up to 2 × 0.5 m2) electrodes with a surface resistivity spanning over several orders of magnitude (0.01 ÷ 10 GΩ/□). Two detector layout has been developed: the baseline layout with the DLC connected to the HV by a single dot connection outside the active area and the high rate layout with a screen printing a conductive grid onto the DLC film, which exploit the concept of the high density current evacuation scheme first introduced for the μ-RWELL. Besides the use in HEP experiments as timing detector this new technology could be exploited as thermal neutron device for homeland security applications (e.g. Radioactive Portal Monitors for ports and airports), replacing one or both DLC electrodes of the sRPC with plates coated with ∼3 μm thick 10B4C layer, thus obtaining neutron converters inside the active volume of the detector. Results obtained by irradiating the detectors at the calibrated 241Am-B ENEA-Frascati HOTNES facility will be discussed.

URANIA: μ-RWELL and sRPC for neutron detection

The goal of the uRANIA-V (μ-RWELL Advanced Neutron Imaging Apparatus) project is the development of an innovative thermal neutron detector based on micro-Resistive WELL (μ-RWELL) technology and surface Resistive Plate Counter (sRPC) technology. A thin layer of 10B4C on the cathode surface allows the thermal neutron conversion into 7Li and α ions to be easily detected in the active volume of the device. These charged particles ionize the gas in the detectors and the readout measures the signal. Test results with different converter layouts show that a thermal neutron (25meV) detection efficiency between 5 ÷ 10 % can be achieved with a single detector. A detailed comparison between the experimental data and the full simulation of the neutron physics and the detector behavior has been performed. Future applications of these technologies range from neutron diffraction imaging to radioactive waste monitor or radiation portal monitoring for homeland security. In this proceeding, the results of the neutron conversion optimization of the Boron thickness and the converted geometry will be discussed together with the development of new electronics integrated with μ-RWELL and sRPC. Experimental results and simulation measurements will be compared.

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.

The surface Resistive Plate Counter: An RPC based on resistive MPGD technology

The surface Resistive Plate Counter (sRPC) is a revolutionary RPC based on surface resistive electrodes realized with Diamond-Like-Carbon sputtered on Apical® foil. Exploiting high granularity current evacuation schemes developed for resistive MPGD and using electrodes with low surface resistivity (down to ∼100MΩ/□), sRPCs standing particle fluxes up to several hundreds kHz/cm2 should be easily developed. The scalability of the technology allows the construction of detectors for large area applications at future high luminosity colliders.

High time resolution, two-dimensional position sensitive MSMGRPC for high energy physics experiments

Two Multi-Strip Multi-Gap Resistive Plate Counters (MSMGRPCs) designed to cope with the high counting rates and track densities of the most challenging zone of the CBM-TOF wall were successfully tested in-beam in the mCBM experimental setup installed at SIS18/GSI Darmstadt facility (FAIR Phase-0). At low counting rate a 96% efficiency plateau and 45 ps time resolution were obtained. The high counting rate test showed ∼50 ps time resolution and an efficiency ≥90% at the maximum delivered counting rate of 30 kHz/cm2. For the mitigation of the gas pollution aging effects, a new detector architecture with a direct gas flow through the gas gaps is proposed. The assembled prototype was tested in-beam in the mCBM setup, obtaining similar performances with the ones obtained for the prototypes with gas exchange via diffusion.

The surface Resistive Plate Counter: A new RPC based on resistive MPGD technology

The surface Resistive Plate Counter (sRPC) is a new RPC based on surface resistive electrodes realized with Diamond-Like-Carbon (DLC) sputtered on Apical\\protect \\relax \\special {t4ht=®} foil. Exploiting the high rate resistive MPGD technology, detectors able to stand several tens of kHz/cm2 can be easily developed. The scalability of the technology allows the construction of detectors for large area applications at future high luminosity colliders.

Ageing studies of Multi-Strip Multi-Gap Resistive Plate Counters based on low resistivity glass electrodes in high irradiation dose

Detailed tests and analysis of ageing effects of high irradiation dose on Multi-Strip Multi-Gap Resistive Plate Counters (MSMGRPC) based on low resistivity glass electrodes, foreseen to be used for the most forward polar angles covered by the Time-of Flight (ToF) sub-detector of the Compressed Baryonic Matter (CBM) experiment at Facility for Antiprotons and Ion Research (FAIR) — Darmstadt are reported. The tests were performed at a multi-purpose irradiation facility of IFIN-HH based on 60Co source. MSMGRPC efficiency, cluster size, surface and volume resistivity of the glass electrodes after irradiation are measured and compared with their values before irradiation. The results of a comprehensive analysis of the composition and properties of the deposited layers on the glass electrodes, based on different methods, i.e. Scanning Electron Microscope (SEM), X-ray Photoelectron Spectroscopy (XPS), foil Elastic Recoil Detection Analysis (ERDA), Rutherford Backscattering Spectrometry (RBS), Atomic Force Microscopy (AFM) and Terahertz Time Domain Spectroscopy (THz-TDS), are presented.

Towards the construction of the inner zone of the CBM-TOF wall

The Time-of-Flight (TOF) subsystem, one of the core detectors of the CBM experiment, is dedicated to the identification of all charged hadrons produced in beam-target interaction. The targeted system time resolution of 80 ps and an efficiency above 90% should be maintained at a particle flux up to 30 kHz/cm2 in the region of low polar angles. In order to cope with these challenging requirements, CBM-TOF wall will be equipped with Multi-Gap Resistive Plate Counters with Multi-Strip readout (MSMGRPC).Our R&D activity has been focused on the development of a MSMGRPC prototype for the most demanding region of the CBM-TOF wall, the region of low polar angles (from 2.5° to ∼12° around the beam pipe). The results obtained in heavy ion in-beam tests have demonstrated the performances of the developed prototypes in conditions of exposure of the whole active area to high flux and high multiplicity reaction products. The latest developed prototypes have an optimized design which fulfills simultaneously two important requirements for MSMGRPCs, the granularity for the inner zone of the CBM-TOF subdetector and the impedance matching to the front-end electronics. Based on the obtained in-beam test results and the architecture of the developed prototypes, a modular structure of 12 units called modules is proposed. A total number of 470 MSMGRPCs (~30000 readout channels) assures an uniform coverage of the active area.

In-beam test of the RPC architecture foreseen to be used for the CBM-TOF inner wall

The Time Of Flight (TOF) subsystem is one of the main detectors of the CBM experiment. The TOF wall in conjunction with Silicon Tracking System (STS) is foreseen to identify charged hadrons, i.e. pions, kaons and protons, with a full azimuthal coverage at 2.50 - 250 polar angles. A system time resolution of at least 80 ps, including all contributions, such as electronics jitter and the resolution of the time reference system, is required. Such a performance should be maintained up to a counting rate larger than 30 kHz/cm2 at the most inner region of TOF wall.Our R&D activity has been focused on the development of two-dimensional position sensitive Multi-gap Resistive Plate Counter (MRPC) prototypes for the forward region of the CBM-TOF subdetector, the most demanding zone in terms of granularity and counting rate.The in-beam tests using secondary particles produced in 30 GeV/u Pb ion collisions on a Pb target at SPS - CERN aimed to test the performance of these prototypes in conditions similar to the ones expected at SIS100 at FAIR. The performance of the prototypes is studied in conditions of exposure of the whole active area of the chamber to high multiplicity of reaction products.The results show that this type of MRPC fulfill the challenging requirements of the CBM-TOF wall. Therefore, such an architecture is recommended as basic solution for CBM-TOF inner zone.

Multiple shell shower fronts in EAS with ARGO-YBJ

The ARGO-YBJ experiment is an Extensive Air Shower array that has been operated at the high altitude Yangbajing Cosmic Ray Laboratory (Tibet, P.R. China 4300 m a.s.l.) in its final configuration since December 2007 until February 2013. The detector consists of a dense layer of Resistive Plate Counters (RPCs) covering an area of about 11000 m2. It has been designed to measure the temporal and spatial structure of Extensive Air Showers (EAS) with high space-time resolution. The detector gives a quite highly detailed picture of shower footprints at ground. It is perfectly suitable to understand the EAS morphology. These detector characteristics have been used for seeking particles of large rest mass produced in cosmic rays by measuring the Multiple Shell Shower Fronts relative delays. The technique and preliminary results will be illustrated in the present work.

A model for the formation of defects in RPC bakelite plates at high radiation levels

This study analyzes in detail the defects in bakelite observed in Resistive Plate Counters (RPC) after exposure to high-radiation environment and fluxed with humidified gas mixture at 9 kV voltage. Objective of this study was to identify the nature of defects and their formation mechanism. The defects were observed firstly on the whole RPC inner surface, and their localization mapped. The defected areas have been analyzed with optical and electron microscopy (SEM), and chemically by EDS (Energy Dispersion Spectroscopy) techniques. An area particularly defect-rich also analysed by x-ray diffraction (XRD). Samples of new and fluxed bakelite have been chemically analyzed by ICP-Plasma (via sample total digestion) in order to determine trace elements variations in composition. model is proposed to explain the chemistry of the formation process.

A study of gas contaminants and interaction with materials in RPC closed loop systems

Resistive Plate Counters (RPC) detectors at the Large Hadron Collider (LHC) experiments use gas recirculation systems to cope with large gas mixture volumes and costs. In this paper a long-term systematic study about gas purifiers, gas contaminants and detector performance is discussed. The study aims at measuring the lifetime of purifiers with new and used cartridge material along with contaminants release in the gas system. During the data-taking the response of several RPC double-gap detectors was monitored in order to characterize the correlation between dark currents, filter status and gas contaminants.

Monitoring relative humidity in RPC detectors by use of fiber optic sensors

We propose to adopt Fiber Bragg Grating technology to develop an innovative sensor for monitoring relative humidity of the gas fluxed in Resistive Plate Counters. Use of Fiber Bragg Grating as sensing device makes the proposed sensor well suited to develop distributed real-time monitoring systems to be installed on large volume detectors operated in high electromagnetic fields. In fact Fiber Bragg Gratings are fully immune from electromagnetic disturbances and allow simplified wiring by in-series interconnection of tens of them along a single optical fiber. In this paper we present results intended to investigate the feasibility of our proposal.

Gas monitoring in RPC by means of non-invasive plasma coated POF sensors

Resistive Plate Counters (RPC) are employed as muon detectors in many high-rate high-energy physics experiments, such as the Compact Muon Solenoid (CMS) experiment currently under way in the Large Hadron Collider (LHC) accelerator at the European Center for Nuclear Research (CERN). A gas mixture containing C2H2F4, i−C4H10 and SF6 is recirculated inside the RPCs during their use and subjected to degradation due to the production of fluoride ions which limits the sensitivity of the RPCs. This paper describes a new sensor that is able to detect low concentrations of fluoride ions in gas mixtures.The sensor is made of a plastic optic fiber (POF) which is made sensitive to F− gaseous ions by means of a thin layer of a glass-\\it like\\rm material, deposited via plasma onto the fiber core. The F− ions attack the glass-\\it like\\rm film and alter the transmission capability of the fiber so that the detection simply requires a LED and a photodiode. The sensor exploits a cumulative response which makes it suitable for direct estimation of the total exposure to the F− ions, thus providing a tool that can be used to tune the maintenance of the gas filters. The glass-\\it like\\rm film is deposited by means of plasma enhanced chemical vapor deposition (PECVD) of organosilicons monomers, which allows the deposition to be performed a low temperature in order to avoid damaging the fiber core.

Retgem with polyvinylchloride electrodes

This paper presents a new design of Gas Electron Multiplier (GEM) based on electrodes made of polyvinylchloride plastic (PVC)-Resistive Electrode Thick GEM (RETGEM). Our device can operate with the gain up to 105 as a conventional GEM at low counting rates and as RPC (Resistive Plate Counter) in case of high counting rates without the transit to the violent sparks. The distinct feature of present RETGEM is the absent of the metal coating and lithographic technology for manufacturing of the protective dielectric rims. The electrodes made of PVC permit us to make the holes by a simple drilling machine. RETGEM-like detectors could be useful in many fields of application requiring a cheaper manufacturing and safer operation, for example, in large neutrino experiments, in TPC, RICH systems, etc.

Toward a high granularity and high counting rate, differential readout timing MRPC

Abstract A new differential architecture of a resistive plate counter based on high granularity strip structure readout electrodes, symmetric relative to the central anode, is proposed. Details of its design and construction are introduced. Results of the 60Co source tests and of the in-beam investigations using minimum ionizing particles are discussed. A time resolution of 50–60 ps and a cluster size of ∼ 1.4 strips were obtained. These results together with previous ones based on low resistivity glass electrodes [1] open the perspective to built large area time-of-flight (TOF) detectors with a very good time resolution and high granularity for high intensity fixed target experiments.

High-rate timing RPC with ceramics electrodes

A resistive plate counter for timing purposes in the high-rate environment of the Compressed Baryonic Matter Experiment has been developed at the Forschungszentrum Dresden-Rossendorf. The detector electrodes are made of a ceramics composite. Detector tests have been performed with minimum ionizing single electrons, delivered by the electron accelerator ELBE with a time accuracy of few picoseconds. The ceramics RPC shows an all-time high-rate capability for electron fluxes up to 2.7 × 10 5 s − 1 cm − 2 .

Ceramics high rate timing RPC

A resistive plate counter for timing purposes in the high rate environment of the Compressed Baryonic Matter Experiment has been developed at the Forschungszentrum Dresden-Rossendorf. The detector electrodes are made of a ceramics composite whose volume resistivity can be tuned in the production process over five orders of magnitude. The detector prototype has been tested with single electrons of 32 MeV. It shows an all-time high rate capability for electron fluxes up to 5×10 5 s −1 cm −2.

Gamma-ray astronomy with the ARGO-YBJ experiment

The ARGO-YBJ experiment is an Extensive Air Shower detector which combines high altitude location (Tibet, People's Republic of China, 4300 m a.s.l.) and full coverage with Resistive Plate Counters, resulting in an energy threshold of a few hundred GeV. The large field of view (~2 sr) and high duty cycle allow the continuous monitoring of the Northern sky, searching for unknown sources and unpredictable events, such as flares in blazar emissions or high energy Gamma Ray Bursts. In this paper I will present some results obtained in γ-ray astronomy with the ARGO-YBJ experiment.

Physics and astronomy results with the ARGO-YBJ experiment

The ARGO-YBJ detector, installed at the Yangbajing Cosmic Ray Laboratory (Tibet, China), at 4300m a.s.l., is a full coverage layer of Resistive Plate Counters with an area of about 6.700 m 2 . The high space-time granularity, the full-coverage technique and the high altitude location make this detector a unique device for a detailed study of atmospheric shower characteristics and allow the investigation of a large variety of astrophysical phenomena. In this work a status report on ARGO-YBJ physics and astronomy results will be presented.