Resistive Plate Chamber Detectors Research Articles

Comparative study of 150 keV Ar+ and O+ ion implantation induced structural modification on electrical conductivity in Bakelite polymer

A comparative study of 150 keV argon (Ar+) and oxygen (O+) ion implantation induced microstructural modifications in Bakelite Resistive Plate Chamber (RPC) detector material at different implantation fluences have been studied using Positron Annihilation Lifetime Spectroscopy (PALS). Positron lifetime parameters viz., o-Ps lifetime (τ3) and its intensity (I3) upon lower implantation fluences can be interpreted as the cross-linking and the increased local temperature induced diffusion followed by trapping of ions in the interior polymer voids. The increased o-Ps lifetime (τ3) at higher O+ ion implantation fluences indicates chain scission owing to the oxidation and track formation. This is also justified by the X-Ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) results. The modification in the microstructure and electrical conductivity of Bakelite materials are more upon implantation of O+ ions than Ar+ ions of same energy and fluences. The reduced electrical conductivity of Bakelite polymer material upon ion implantation of both the ions is correlated to the conducting pathways and cross-links in the polymer matrix. The appropriate energy and fluence of implanting ions might reduce the leakage current and hence improve the performance of Bakelite RPC detectors.

Timing and charge measurement of single gap resistive plate chamber detectors for INO—ICAL experiment

The recently approved India-based Neutrino Observatory will use the world’s largest magnet to study atmospheric muon neutrinos. The 50 kiloton Iron Calorimeter consists of iron alternating with single-gap resistive plate chambers. A uniform magnetic field of ∼1.5 T is produced in the iron using toroidal-shaped copper coils. Muon neutrinos interact with the iron target to produce charged muons, which are detected by the resistive plate chambers, and tracked using orthogonal pick up strips. Timing information for each layer is used to discriminate between upward and downward traveling muons. The design of the readout electronics for the detector depends critically on an accurate model of the charge induced by the muons, and the dependence on bias voltages. In this paper, we present timing and charge response measurements using prototype detectors under different operating conditions. We also report the effect of varying gas mixture, particularly SF6, on the timing response.

Effect of electron beam irradiation on the microstructure, optical and electrical properties of glass resistive plate chamber detector material

The glass resistive plate chamber (RPC) detector materials were exposed to 8 MeV electron beam from 20 to 100 kGy in steps of 20 kGy. In order to study the electron beam irradiation-induced effects in glass RPC detector material, positron annihilation lifetime spectroscopy (PALS), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopic investigations were carried out. PALS analysis at lower electron doses indicates the increased void size with the creation of additional sites in the glass network. This is attributed to the breakage of Si–O bonds at the regular tetrahedral sites of Si–O–Si up to 40 kGy. The reduced void size at higher irradiation doses indicates the increased chemical bonding between the tetrahedral sites of Si–O–Si and hence increases the short-range order in the silica glass. These changes are complement with the XRD, FTIR results and the measured electrical conductivity. The variation of AC conductivity with frequency obeys Jonscher power law in all the electron irradiation doses at room temperature. The variation in optical band gap energy from the ultraviolet–visible (UV–Vis) spectra inferred the elimination of defects accumulation at higher irradiation doses due to the glass network close packing.

Oxygen ion implantation induced structural modifications and electrical conductivity in glass RPC detector materials: A positron lifetime study

Resistive Plate Chamber (RPC) detector materials viz., Asahi and Saint Gobain float glasses were exposed to 500keV and 1MeV oxygen ions at diverse fluences. Positron Annihilation Lifetime Spectroscopic (PALS) investigations were carried out to explore the ion implantation induced microstructural modifications in these glasses. Positron lifetime parameters at lower ion implantation fluences suggests the breakage of SiO bonds at the regular tetrahedral sites of SiOSi and the displacement of molecules due to the formation of track inside the silicate glass structure in Asahi glass samples. In both the glasses, the reduced void size at higher ion implantation fluences indicates the increased chemical bonding between the tetrahedral sites and hence increases the short range order. The local temperature induced diffusion followed by trapping of ions in the interior glass voids is predominant at higher fluences. The microstructural modifications and electrical conductivity in both the glasses were well correlated with the measured free volume parameters. The variation in optical band gap from the UV–Vis absorption edge inferred the possibility of strain mismatch in the glass network by the elimination of defects at higher implantation fluences. This is complementary with Fourier Transform Infrared (FTIR) results.

Study of timing response and charge spectra of glass based Resistive Plate Chamber detectors for INO-ICAL experiment

Resistive Plate chambers (RPCs) are robust and affordable gaseous detectors that combine low cost with excellent timing, good spatial resolution and fast response to the incoming particles. The India Based Neutrino Observatory is an approved project aimed at building a magnetised Iron Calorimeter (ICAL) detector to study Neutrino physics and related issues. The ICAL experiment will utilize about 29000 RPC's as active detector elements, sandwiched between alternate plates of thick iron. The RPC detectors will be used to detect muons produced from the atmospheric neutrinos interaction with an iron target. The spatial information of the muons will be extracted from the two dimensional readout and the hit position in the respective layers. The up going and down going directionality will be obtained using the time stamp of hits in the active detectors. The charge induced by the particle and its behaviour with respect to the applied voltage play a significant role in designing the readout electronics for the detector. In this paper, we present the timing and charge measurement of single gap glass based RPC detectors. We will also report about studies on the dependence of the timing and charge response of these RPC detectors as a function of the gas composition.

Measurement of characteristic impedance of silicon fiber sheet based readout strip panel for RPC detector in INO

The India-based Neutrino Observatory (INO) is a mega science project of India, which is going to use about 30,000 Resistive Plate Chambers (RPC) as active detector elements for the study of atmoshpheric neutrino oscillations. Each RPC detector will consist of two orthogonally placed readout strip panel for picking the signals generated in the gas chamber. The area of RPC detector in INO-ICAL (Iron Calorimeter) experiment will be 2 m × 2 m, therefore the dimensions of readout strip panel should also be 2 m × 2 m. To get undistorted signals pass through the readout strip panel to front-end electronics, their characteristic impedance should be matched with each other. In the present paper, we describe the need and search of new dielectric material for the fabrication of flame resistant, waterproof and flexible readout strip panel. We will also describe the measurement of characteristic impedance of Plastic Honeycomb (PH) based readout strip panel and Silicon Fiber Sheet (SFS) based readout strip panel in a comparative way, and its variation under loading and with time. Based on this study, we found that a 5 mm thick SFS-based readout strip panel has a minimum signal reflection at 49.5 ohm characteristic impedance value. Our study shows that SFS is a good dielectric material for the purpose.

Development and characterization of single gap glass RPC

India-based Neutrino Observatory (INO) facility is going to have a 50kton magnetized Iron CALorimeter (ICAL) detector for precision measurements of neutrino oscillations using atmospheric neutrinos. The proposed ICAL detector will be a stack of magnetized iron plates (acting as target material) interleaved with glass Resistive Plate Chambers (RPCs) as the active detector elements. An RPC is a gaseous detector made up of two parallel electrode plates having high bulk resistivity like that of a float glass and bakelite. For the ICAL detector, glass is preferred over bakelite as it does not need any kind of surface treatment to achieve better surface uniformity and also the cost of associated electronics is reduced. Under the detector R&D efforts for the proposed glass RPC detector, a few glass RPCs of 1m × 1m dimension are fabricated procuring glass of ∼2mm thickness from one of the Indian glass manufacturers (Asahi). In the present paper, we report the characterization of RPC based on leakage current, muon detection efficiency and noise rate studies with varying gas compositions.

Development and commissioning of the HARDROC based readout for the INO-ICAL experiment

Glass based Resistive Plate Chambers (RPCs) are going to be used as an active element in the Iron Calorimeter (ICAL) experiment at the India based Neutrino Observatory (INO), which is being constructed to study atmospheric neutrinos. Though the RPC detector operational parameters are more or less finalized, the readout electronics is being developed using various technologies. The ICAL experiment will consist of about 29,000 RPC detectors of 2 m × 2 m in size with each detector having 64 readout channels both in the X and Y directions. The present study focusses on multi-channel electronics based on SiGe 350 nm technology as an option for the INO-ICAL RPC detectors. The study includes commissioning and usage of frontend application specific integrated circuit (ASIC) HARDROC chip in which 64 channels are handled independently to perform zero suppression. We present first testbench results using the HARDROC chip with the aim to use it finally in the ICAL experiment.

Effect of glass thickness variations on the performance of RPC detectors

The India-based Neutrino Observatory (INO) is planning to build a magnetized iron calorimeter detector (ICAL) in which Resistive Plate Chambers (RPCs) will be the active detector elements. A study of the performance of RPCs, made using electrodes of various thicknesses, is pivotal in optimizing the design parameters of the ICAL RPCs. We fabricated RPCs with glasses of various thicknesses and studied their performance in the same environmental conditions. A study of detector efficiency, noise rate, time resolution and charge distribution is presented in this paper.

Design and characterization of the PREC (Prototype Readout Electronics for Counting particles)

The design, tests and performance of a novel, low noise, acquisition system—the PREC (Prototype Readout Electronics for Counting particles) is presented in this article. PREC is a system developed using discrete electronics for particle counting applications using RPCs (Resistive Plate Chamber) detectors. PREC can, however, be used with other kind of detectors that present fast pulses, e.g. Silicon Photomultipliers. The PREC system consists in several Front-End boards that transmit data to a purely digital Motherboard. The amplification and discrimination of the signal is performed in the Front-End boards, making them the critical component of the system. In this paper, the Front-End was tested extensively by measuring the gain, noise level, crosstalk, trigger efficiency, propagation time and power consumption. The gain shows a decrease with the working temperature and an increase with the power supply voltage. The Front-End board shows a low noise level (≤ 1.6 mV at 3σ level) and no crosstalk is detected above this level. The s-curve of the trigger efficiency is characterized by a 3 mV gap from the region where most of the signals are triggered to almost no signal is triggered. The signal transit time between the Front-End input and the digital Motherboard is estimated to be 5.82 ns. The maximum power consumption is 3.372 W for the Motherboard and 3.576 W and 1.443 W for each Front-End analogue circuitry and digital part, respectively.

Effect of electrical properties of glass electrodes on the performance of RPC detectors for the INO-ICAL experiment

The India-based Neutrino Observatory (INO) collaboration has chosen glass Resistive Plate Chambers (RPCs) as the active detector elements for the Iron Calorimeter (ICAL) experiment. In the present work, we study the electrical properties such as bulk resistivity and relative permittivity of the glasses from two different manufacturers and compared the performances of RPCs built using these glasses. We conclude that the glass electrodes with larger bulk resistivity and permittivity are better suited for manufacturing RPCs for the ICAL experiment, as these detectors could be operated at lower bias currents and voltages, and produce better time resolution compared to those built with glass electrodes of smaller bulk resistivity and permittivity.

Study of glass properties as electrode for RPC

Operation and performance of the Resistive Plate Chambers (RPCs) mostly depend on the quality and characteristics of the electrode materials. The India-based Neutrino Observatory collaboration has chosen glass RPCs as the active detector elements for its Iron Calorimeter detector and is going to deploy RPCs in an unprecedented scale. Therefore, it is imperative that we study the electrode material aspects in detail. We report here, systematic characterization studies on the glasses from two manufacturers. RPC detectors were built using these glasses and performances of the same were compared with their material properties.

Resistive Plate Chamber digitization in a hadronic shower environment

The CALICE Semi-Digital Hadronic Calorimeter technological prototype is a sampling calorimeter using Glass Resistive Plate Chamber detectors with a three-threshold readout as the active medium. This technology is one of the two options proposed for the hadronic calorimeter of the International Large Detector for the International Linear Collider. The prototype was exposed to beams of muons, electrons and pions of different energies at the CERN Super Proton Synchrotron. To be able to study the performance of such a calorimeter in future experiments it is important to ensure reliable simulation of its response. This paper presents the SDHCAL prototype simulation performed with GEANT4 and the digitization procedure achieved with an algorithm called SimDigital. A detailed description of this algorithm is given and the methods to determinate its parameters using muon tracks and electromagnetic showers are explained. The comparison with hadronic shower data shows a good agreement up to 50 GeV. Discrepancies are observed at higher energies. The reasons for these differences are investigated.

Performance study of glass RPC detectors for INO-ICAL experiment

Resistive plate chamber (RPC) detectors are known for their excellent timing and good spatial resolution which make them favorable candidate for tracking and triggering in many high energy physics experiments. The Iron Calorimeter (ICAL) detector at India-based Neutrino Observatory (INO) is one such experiment which will use RPCs as an active detector element. The ICAL experiment is designed to study atmospheric neutrinos and various issues related with neutrino physics. The INO-ICAL has geometry that utilizes about 29,000 RPCs of 2×2m2 in size, interleaved between thick iron plates, producing muons via the interaction of atmospheric neutrinos with iron. The tracking information of the muons will be extracted from the two-dimensional readout of the RPCs and its position in respective layers along with the upward and downward directionality determined from the timing information. As a result, a precise measurement of timing response of these RPC detectors is quite important. Furthermore, to design readout system for the ICAL detector, induced signal study and charge information is needed as well. In this paper, we present a detailed timing and charge spectra study for various glass RPC candidates. We also report the effect of various gas compositions on the timing and charge spectra of these RPC detectors.

RPC detector characteristics and performance for INO-ICAL experiment

The India-based Neutrino Observatory (INO) is an approved multi-institutional collaboration neutrino physics project, aimed at building an underground laboratory in the southern India. INO will utilize a large magnetized Iron Calorimeter (ICAL) detector to study the atmospheric neutrinos, and to explore the unresolved issues related to neutrinos. The Resistive Plate Chambers (RPCs), interleaved in between iron absorber layers, are going to be used as the active signal readouts for the ICAL experiment at INO. The research and development is carried out to find structural quality and electrical response for RPC electrode materials available within local domain. The assembled 2 mm gap RPCs are tested using cosmic muons for their detection performance. The study also incorporates preliminary results on detector timing and signal induced charge measurements.

Effects of variation of environmental parameters on the performance of Resistive Plate Chamber detectors

Performance of single gap Resistive Plate Chamber (RPC) detectors is investigated under variation of environmental parameters, such as temperature and relative humidity. Operational characteristics of the RPCs depend on both the environmental temperature and the relative humidity. Sensitivity to such dependence is found to be more on temperature rather than the relative humidity. Qualitative interpretation of some of the results obtained is given based on the known properties of the electrode materials and gases used in the detectors.

Joint measurement of the atmospheric muon flux through the Puy de Dôme volcano with plastic scintillators and Resistive Plate Chambers detectors

AbstractThe muographic imaging of volcanoes relies on the measured transmittance of the atmospheric muon flux through the target. An important bias affecting the result comes from background contamination mimicking a higher transmittance. The MU‐RAY and TOMUVOL collaborations measured independently in 2013 the atmospheric muon flux transmitted through the Puy de Dôme volcano using their early prototype detectors, based on plastic scintillators and on Glass Resistive Plate Chambers, respectively. These detectors had three (MU‐RAY) or four (TOMUVOL) detection layers of 1 m2 each, tens (MU‐RAY) or hundreds (TOMUVOL) of nanosecond time resolution, a few millimeter position resolution, an energy threshold of few hundreds MeV, and no particle identification capabilities. The prototypes were deployed about 1.3 km away from the summit, where they measured, behind rock depths larger than 1000 m, remnant fluxes of 1.83±0.50(syst)±0.07(stat) m−2 d−1 deg−2 (MU‐RAY) and 1.95±0.16(syst)±0.05(stat) m−2 d−1 deg−2 (TOMUVOL), that roughly correspond to the expected flux of high‐energy atmospheric muons crossing 600 meters water equivalent (mwe) at 18° elevation. This implies that imaging depths larger than 500 mwe from 1 km away using such prototype detectors suffer from an overwhelming background. These measurements confirm that a new generation of detectors with higher momentum threshold, time‐of‐flight measurement, and/or particle identification is needed. The MU‐RAY and TOMUVOL collaborations expect shortly to operate improved detectors, suitable for a robust muographic imaging of kilometer‐scale volcanoes.

Construction and commissioning of a technological prototype of a high-granularity semi-digital hadronic calorimeter

A large prototype of 1.3 m3 was designed and built as a demonstrator of the semi-digital hadronic calorimeter (SDHCAL) concept proposed for the future ILC experiments. The prototype is a sampling hadronic calorimeter of 48 units. Each unit is built of an active layer made of 1 m2 Glass Resistive Plate Chamber (GRPC) detector placed inside a cassette whose walls are made of stainless steel. The cassette contains also the electronics used to read out the GRPC detector. The lateral granularity of the active layer is provided by the electronics pick-up pads of 1 cm2 each. The cassettes are inserted into a self-supporting mechanical structure built also of stainless steel plates which, with the cassettes walls, play the role of the absorber. The prototype was designed to be very compact and important efforts were made to minimize the number of services cables to optimize the efficiency of the Particle Flow Algorithm techniques to be used in the future ILC experiments. The different components of the SDHCAL prototype were studied individually and strict criteria were applied for the final selection of these components. Basic calibration procedures were performed after the prototype assembling. The prototype is the first of a series of new-generation detectors equipped with a power-pulsing mode intended to reduce the power consumption of this highly granular detector. A dedicated acquisition system was developed to deal with the output of more than 440000 electronics channels in both trigger and triggerless modes. After its completion in 2011, the prototype was commissioned using cosmic rays and particles beams at CERN.

Evaluation of resistive-plate-chamber-based TOF-PET applied to in-beam particle therapy monitoring

Particle therapy is a highly conformal radiotherapy technique which reduces the dose deposited to the surrounding normal tissues. In order to fully exploit its advantages, treatment monitoring is necessary to minimize uncertainties related to the dose delivery. Up to now, the only clinically feasible technique for the monitoring of therapeutic irradiation with particle beams is Positron Emission Tomography (PET). In this work we have compared a Resistive Plate Chamber (RPC)-based PET scanner with a scintillation-crystal-based PET scanner for this application. In general, the main advantages of the RPC-PET system are its excellent timing resolution, low cost, and the possibility of building large area systems. We simulated a partial-ring scanner based on an RPC prototype under construction within the Fondazione per Adroterapia Oncologica (TERA). For comparison with the crystal-based PET scanner we have chosen the geometry of a commercially available PET scanner, the Philips Gemini TF. The coincidence time resolution used in the simulations takes into account the current achievable values as well as expected improvements of both technologies. Several scenarios (including patient data) have been simulated to evaluate the performance of different scanners. Initial results have shown that the low sensitivity of the RPC hampers its application to hadron-beam monitoring, which has an intrinsically low positron yield compared to diagnostic PET. In addition, for in-beam PET there is a further data loss due to the partial ring configuration. In order to improve the performance of the RPC-based scanner, an improved version of the RPC detector (modifying the thickness of the gas and glass layers), providing a larger sensitivity, has been simulated and compared with an axially extended version of the crystal-based device. The improved version of the RPC shows better performance than the prototype, but the extended version of the crystal-based PET outperforms all other options.

Electronically Conductive Vanadate Glasses for Resistive Plate Chamber Particle Detectors

Particle detectors are constantly being built and refitted with new technology to improve the spatial resolution, radiation hardness, and speed at which the detector can capture particle events. One of the most crucial components of a modern collider experiment is the hadron calorimeter. One of the proposed improvements on future hadron calorimeters is to utilize resistive plate chambers (RPCs). They provide the spatial and energy resolution as well as could provide speed and radiation hardness. RPCs depend on manufacturing electrically conductive glasses that are mechanically strong, durable, radiation resistant, and not ionically conductive. To achieve such requirements, vanadate glasses were developed as alternatives to current prototypes which use soda lime silicate glasses. The conductivity, oxidation states of vanadium, radiation hardness, as well as the prototype performance, were tested on vanadate glasses. The prototype tests show that using 0.40ZnO−0.40TeO2−0.20V2O5 can improve the RPC detector rate up to 100 times.