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The XIII Workshop on Resistive Plate Chambers and Related Detectors (RPC2016), is hosted by Ghent University, Ghent, Belgium, at congress center Het Pand.
The poster of the conference is available here. More information is available on the official conference website at http://rpc2016.ugent.be
The online payment tool for the registration fee is accessible here until Monday evening, Feb. 22, 2016.
In high energy physics experiments, the MRPC (Multi-Gap Resistive Plate Chamber) detectors are widely used recently which can provide higher-resolution measurement for particle identification. However, the application of MRPC detectors leads to a series of challenges in electronics design especially the accurate clock distribution with large number of front-end electronic channels over wide range. To deal with these challenges, this paper presents a universal scheme of clock transmission network for MRPC-based experiments with advantages of both precise clock distribution and global command synchronization. For precise clock distribution, the clock network is designed into a star architecture with two stages: the first one has a point-to-multipoint long range bidirectional distribution with optical channels and the second one has a fan-out structure with copper link inside readout crates. To guarantee the clock precision of frequency and phase, the PTP (Precision Time Protocol) and the DDMTD (digital Dual Mixer Time Difference) methods are used for frequency synthesis, phase measurement and adjustment, which is implemented by FPGA (Field Programmable Gate Array) in real-time. In addition, to achieve global command synchronization, based upon this clock distribution network, synchronous signals are coded with clock for transmission. With technique of encoding/decoding and clock data recovery, signals such as global triggers and system control commands, can be distributed to all front-end channels synchronously, which greatly simplifies the system design. The experimental results show that both the clock jitter (RMS) and the clock skew are less than 100 ps.
The development of Resistive Plate Chambers (RPCs) with improved features like high rate capabilities, higher efficiency in smaller form factors or bigger induced signals requires resistive electrode materials with a specific set of properties. Designing materials for this purpose with specified values of electrical conductivity, that are not usually found in single phase materials, in addition with very good mechanical, chemical, thermal and electrical stabilities has represented a considerable defy in the ambit of materials science, especially when economical aspects are taken into account. Unfortunately, only few materials for electrodes satisfying all these conditions have been found. Even though, the situation worsens when the materials were stressed in the gas discharge environment. We have found that materials that fulfill all of the previously established specifications, even with similar secondary emission, skip the Towsend discharge regime at lower gain than the usual electrode materials. This fact suggests that new requirements for RPC electrode materials should be considered. According to our results, we have found that the chemical nature of the anode seems to have a strong influence on the stability of the avalanche gas conduction regime. This unexpected result was addressed by depositing very thin oxide layers with nm accuracy over polished surfaces of the new materials. Although these films do not significantly modify the electric field distribution inside the RPC, we have found that some thin films stabilize the avalanche regime. Furthermore, being so thin the deposited layer it do not need to be made of a material with a the same hard requirements of high rate resistive electrodes. In this work, we present a simple but very effective solution to make compatible the desirable features of the bulk material working as high rate resistive electrode and the stability of the detector: covering the material with a thin layer of a second phase that stabilize the avalanche discharge regime. Finally, a phenomenological model to explain the experimental method will be exposed for debate.
In the last two decades Resistive Plate Chambers were employed in the Cosmic Ray Experiments COVER-PLASTEX and ARGO/YBJ. In both experiments the detectors were housed indoors, likely owing to gas distribution requirements and the need to control environment variables that directly affect RPCs operational stability. But in experiments where Extended Air Shower (EAS) sampling is necessary, large area arrays composed by dispersed stations are required, making this kind of approach impossible. In this situation, it will be mandatory to have detectors that could be deployed in standalone stations, with very sparse opportunities for maintenance, and with good resilience to environmental conditions. Aiming to meet these requirements, we started some years ago [1] the development of RPCs for Autonomous Stations. The results from indoor tests and measurements were very promising [2], both concerning performance and stability under very low gas flow rate, which is the main requirement for Autonomous Stations. In this work we update the indoor results and show the first ones concerning outdoor stable operation. In particular, a dynamic adjustment of the high voltage is applied to keep gas gain constant. Evolution in time of E/N, background current/rate and efficiency will be presented. [1] L. Lopes et al., Study of standalone RPC detectors for cosmic ray experiments in outdoor environment, 2013 JINST 8 T03004. [2] L. Lopes et al., Study Resistive Plate Chambers for the Pierre Auger array upgrade, 2014 JINST 9 C10023.
The TOFtracker concept, the simultaneous measurement of accurate time and bi-dimensional space coordinates in a single gaseous detector, has been previously demonstrated [1]. The small detector yielded a time accuracy of 77 ps along with a bi-dimensional position accuracy of 38 um over a full active area of 60 x 60 mm2. Recently, a large area, 1550x1250 mm2, detector has been constructed for the same purpose. The detector is composed by a multigap RPC with four gas gaps of 0.3 mm delimited by 2 mm soda-lime glass plates. The High Voltage (HV) is applied to the outer glasses through a resistive layer applied on the glass surface by airbrush techniques. The stack is enclosed in a plastic gas tight box equipped with gas and HV feed-throughs. Signals are induced in 2.54 mm pitch metallic strips located in each side of the plastic box and coupled to both charge-sensitive and timing circuits. In this work, the performance of this device with cosmic ray muons is reported. [1] A. Blanco, P. Fonte, L. Lopes, P. Martins, J. Michel, M. Palka, M. Kajetanowicz, G. Korcyl, M. Traxler and R. Marques, "TOFtracker: gaseous detector with bidimensional tracking and time-of-flight capabilities", 2012 JINST 7 P11012
The CALICE Semi-Digital Hadronic Calorimeter (SDHCAL) prototype, built in 2011, was exposed to beams of hadrons, electrons and muons in short periods in 2012, 2014 and 2015 on different beam lines of the CERN SPS and PS. The prototype with its up to 50 active layers, made of Glass Resistive Plate Chambers (GRPC) and their embedded readout electronics, was run in triggerless and power-pulsing mode. The performance of the SDHCAL during the test beam was found to be very satisfactory with efficiency exceeding 90% for almost all of the active layers. The first results have shown that a linear response (within ± 5%) and a good energy resolution are obtained for a large range of hadronic energies (5-80~GeV) by applying appropriate calibration coefficients on the collected data. Improved reconstruction methods, like charged particles tracking inside hadronic showers, have been used to improve the first results.
The first technological SDHCAL prototype having been successfully tested, a new phase of R&D, to validate completely the SDHCAL option for the International Linear Detector (ILD) project of the ILC, has started with the conception and the realization of a new prototype. The new one is intended to host few but large active layers of the future SDHCAL. The new active layers, made of GRPC with sizes larger than 2 m2 will be equipped with a new version of the electronic readout fulfilling the requirements of the future ILD detector. The new GRPC are conceived to improve the homogeneity with a new gas distribution scheme. Finally the mechanical structure will use the electron beam welding. The progress realized will be presented and future steps will be discussed.
The possibility of performing 2D vertex reconstruction in the sLHC by resorting to accurate 10-20ps time resolution (per minimum ionizing particle) has triggered a new wave of R&D in the timing frontier. Such detectors will be operating close to the beam, and the anticipated rates exceed those typical of RPCs in many orders of magnitude. We will introduce in this presentation a detector based on a late idea of Charpak, together with Giomataris. It consists on coupling a micro-pattern amplification stage to a 50-200um micro-drift region, the latter receiving the photo-electrons from the Cherenkov emission produced in a highly VUV-transparent crystal (e.g., MgF, CaF). The concept relies on the approximate simultaneity of the Cherenkov photons and thus on the absence of any limiting jitter in the production of the initial photo-electrons that trigger the signal generation process. Diffusion before the amplification stage can be kept small through the minimization of the drift region and a proper gas choice. We will show with the help of simulations that the experimental results obtained with this type of detector are indeed purely diffusion-limited, a concept that sets the natural scale for single-photon time resolution to around or below 100ps. Without an optimal timing gas (Ne+C2H6, 90/10 was used) a time resolution around 200ps(sigma) per photo-electron has been measured on a laser facility, which allows ultra-fast pulses and a good control on the number of photo-electrons. Similar to RPCs, the measured time resolution scales well with the square root of the number of initial electrons, and this should be sufficient for a 40ps time resolution on a~0.5cm spot, already with this early prototype. Besides providing a detailed description of the experimental results, we will examine critically possible improvements on “diffusion-limited” timing related to this new development, and will also discuss them in the context of “avalanche statistics – limited” timing RPCs.
The MultiPurpose Detector (MPD) is designed at JINR for properties of hot and dense baryonic matter study. The MPD is system of detectors surrounding one of the interaction points of the future ion collider NICA. Time-of-Flight identification system in this experiment will be based on MRPC. The MRPC satisfied of requirements of the experiments has been developed. The report presents main parameters of the detector and the latest beam test results. The achieved time resolution is about 40 ps by 99% of efficiency.
Position Sensitive Neutron Detectors (PSNDs) play a critical role in many fields, such as neutron scattering science (NSS), homeland security and well logging. During the last decades these detectors were mainly based on the 3He isotope, the golden standard for thermal neutron detection. Nowadays, however, the 3He crisis resulted in a change of paradigm which poses demanding challenges to develop new types of neutron detectors, capable to satisfy high performance standards. A 3He free position sensitive thermal neutron detector concept which combines the well established Resistive Plate Chambers (RPCs) technology with 10B solid neutron converters has been developed at LIP. Here we report results of a feasibility study of a 10B based thin-gap RPC detector prototype. The high quality boron carbide coatings enriched in 10B were manufactured at the European Spallation Source (ESS) Detector Coatings Workshop in Linköping. The prototype features a thin-gap Hybrid RPC with a metallic cathode coated with a layer of boron carbide enriched in 10B (2 microns thick). The sensitivity to the thermal neutrons is achieved by the nuclear reaction 10B (n, alpha) 7Li through the ionization caused by the fission fragments that reach the gas-gap of the RPC. A PCB with an engraved array of signal pick-up strips, facing the outermost surface of the resistive anode, was read-out by a MAROC3 ASIC. Event positions were determined in one dimension using the Center of Gravity method and the recorded signals amplitude read from individually strips. Experimental results from the tests of the detector on a monochromatic thermal neutron beam at the Institut Laue-Langevin (ILL) will be presented. An extended plateau was observed in the measurement of the count rate versus high voltage. A spatial resolution better than 1 mm FWHM was measured, demonstrating the viability of 10B based thin-gap RPCs for PSNDs with sub-millimeter resolution. The influence of the 4He and 7Li fission fragments ranges in the gas-gap on the spatial resolution will be discussed based on MC simulations. We also present a concept of a 10B multi-layered detector based on a Multi-Gap RPC which is currently under development in the frame of the SINE2020 EU project.
In the CBM (Compressed Baryonic Matter) experiment constructed at the Facility for Anti-proton and Ion Research (Fair) at GSI, Darmstadt, Germany, MRPC(Multi-gap Resistive Plate Chamber) is adopted to construct the large TOF (Time-of-Flight) system to achieve an unprecedented precision of hadron identification, benefiting from its good time resolution, relatively high efficiency and low building price. According to the particle flux rate distribution, the whole CBM-TOF wall is divided into four rate regions named Region D, C, B and A (from inner to outer). Aiming at the Region C and B where the rate ranges from 3.5 to 8.0 kHz/cm2, we’ve developed a kind of double-ended readout strip MRPC. It uses low resistive glass to keep good performance of time resolution under high-rate condition. The differential double stack structure of 2x4 gas gaps help to reduce the required high voltage to half. There are 24 strips on one counter, and each is 270mm long, 7mm wide and the interval is 3mm. Ground is placed onto the MRPC’s electrode and feed through is carefully designed to match the 100Ω impedance of PADI electronics. The prototype of this strip MRPC has been tested with cosmic ray, a 98% efficiency and 60ps time resolution is gotten. In order to further examine the performance of the detector working under higher particle flux rate, the prototype has been tested in the 2014 October GSI beam time and 2015 February CERN beam time. In both beam times a relatively high rate of 1 kHz/cm2 was obtained. The calibration is done with CBM ROOT. A couple of corrections has been considered in the calibration and analysis process (including time-walk correction, gain correction, strip alignment correction and velocity correction) to access actual counter performances such as efficiency and time resolution. An efficiency of 97% and time resolution of 48ps are obtained. All these results show that the real-size prototype is fully capable of the requirement of the CBM-TOF, and new designs such as self-sealing are modified into the strip counter prototype to obtain even better performance. Presentation type: oral
Photoproduction experiments of hadrons using the γ ray from 1.5 to 2.9 GeV have been performed at the SPring-8/LEPS2 facility. We are now taking data with a large acceptance calorimeter (BGOegg) and a forward TOF array consisting of RPCs[1]. After the BGOegg experiment, we will start a new experiment using LEPS2 solenoid spectrometer. The detector system inside of the LEPS2 solenoid msagnet is now under construction and development. The long RPCs with 2-m lengths will be used as barrel TOF counters. The LEPS2 solenoid magnet has a large cylindrical bore whose size is approximately two meters both in diameter and length. Each RPC covers a polar angular region from 30 to 120 degrees in the laboratory system, where the momentum of produced particles are almost less than 1 GeV/c. The particle identification in this momentum region is done by time-of-flight measurement with the RPC. The distance from the target to the RPC is from 1 m for 90 degrees to 2 m for 30 degrees. Since the flight distance is rather short, we need a RPC-TOF system with a high time-resolution around 50ps. In order to reduce the number of readout channels, we are developing an RPC with a 2-m length, based on the 1-m RPC which have been used in the BGOegg experiment[1]. Since the commercially available size of glass and PCB foundation on which the readout strips are printed is only 1 m, we have to connect two glasses and PCB foundations to make the RPC with a 2-m length. In order to construct such RPCs, we need to study the following items: 1. The stability against discharges at the seam of glasses. 2. The time resolution of a readout strip which has a joint. From these viewpoints, we produced two small prototype RPCs which have different joint structures and performed test experiments using the LEPS2 beamline in February 2015. We are now making a 2-m RPC based on the result of the test experiment and will make evaluation of its various performances. we will report the results of these development of the RPCs. [1] N. Tomida, et al., JINST 9 (2014) C10008.
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 35 AGeV will be a 120 m2 large Time-of-Flight (ToF) wall composed of Multi-gap Resistive Plate Chambers (MRPC) with a system time resolution 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/cm2 and 25~kHz/cm2 depending on their location. Characterized by granularity and rate capability the actual design of the ToF-wall foresees 4 different counter types called MRPC1 – MRPC4. In order to elaborate the final MRPC design of these counters several heavy-ion in-beam tests were performed at different facilities. In this contribution we present performance studies under realistic load condition of an impedance-matched fully-differential single high voltage (HV) stack MRPC. Work was supported partially by BMBF 05PRVHC7 and by EU/FP7-HadronPhysics3/WP19.
The INO-ICAL is a proposed neutrino physics experiment in which RPCs are used as active detecting medium. Construction of an Iron Calorimeter (ICAL) detector for studying Neutrinos, consisting of 50Kton of magnetized iron plates arranged in stacks with gaps in between RPCs would be inserted as active detectors, the total number of 2m × 2m RPCs being about 29000. But for 2m×2m normal glass with thickness 3mm is difficult and risky to handle at the time of making RPCs. So this time we made the RPC with toughened glass and characterize it. Toughened or tempered glass is a type of glass processed by controlled thermal or chemical treatments in local glass industry to increase its strength compared with normal glass. This paper compares the characteristics of RPC, e.g., noise rate, dark current, efficiency etc of this toughened glass and of normal glass.
There are many sources of position dependent variation of the intrinsic gain of a single gap RPC, e.g., variation of thickness of glass, button and spacer, different composition of gas due to improper flow of gas, leakage etc. One of the dominant component of the time resolution of a large area single gap RPC is this position dependent gain. Also there is a variation of timing information as a function of strip multiplicity as well as lateral position of the trajectory in RPC strip coordinate. This paper describes the technique of offline time correction to achieve the time resolution better than a ns. This technique is validated using a large cosmic ray data collected in twelve 1m×1m RPC stack at TIFR. This paper also mentioned few alternate solutions to improve the time resolution during the operational phase of INO-ICAL experiment. All these are not only valid for the INO, but valid for any experiment with the large RPC detector.
Resistive plate chamber (RPC) detectors are known for their excellent timing and good spatial resolution, which make them favourable candidates for the 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 29000 RPC’S of 2m x 2m 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 RPC’s and its position in respective layer 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. Further, to design readout system for the ICAL detector, induced signal study and charge information is needed as well. In this paper, we present the 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.
In the framework of the High Luminosity LHC upgrade program of the CMS muon system, several different RPC prototypes have been built and are now under test at the new CERN Gamma Irradiation Facility (GIF++). A dedicated Detector Control System has been developed using the WinCC-OA tool to control and monitor these prototype detectors, and to store the measured parameter data.
The India-based Neutrino Observatory (INO) collaboration is planning to build a 50 kiloton magnetized Iron Calorimeter (ICAL) to precisely study the atmospheric neutrino oscillation parameters. The collaboration has chosen Resistive Plate Chambers (RPCs) made up of float glass electrodes of 1.9 m × 1.8 m in area as the active detector elements and is going to deploy 28,800 of them in the ICAL detector. The RPCs will be operated in the avalanche mode with an optimized gas mixture of HFC−R134a/iso−C4H10/SF6 = 95/4.5/0.5. The experiment is expected to run for more than 10 years in order to record statistically significant number of neutrino interactions for the confirmation of atmospheric neutrino oscillation. Hence, long term stability and performance of the RPCs over the duration of the experiment is of prime concern. About 200,000 liters of gas is going to be circulating in the RPCs during the experiment. The gas lines running into about 135km in total are going to be supply/receive gas to/from the RPC detectors. In spite of stringent QC during the RPC gas gap making or gas lines plumbing, it is impossible to prevent ambient air or water vapor entering into the gas circuit over these long periods of time. The contaminants are known cause for serious degradation in the performance or permanent damage of RPCs. Considering the severe repercussions in the mammoth ICAL detector, a systematic study of this problem was undertaken. Two glass RPCs of 30 cm × 30 cm in size were fabricated and were simultaneously operated with dry gas mixture in one and with gas mixture along with controlled and calibrated amount of water vapor in the other. A common cosmic ray muon telescope was set up for studying both the RPCs. Ambient parameters such as temperature and relative humidity as well as RPCs' operating and performance parameters such as chamber current, noise rate, efficiency, charge collection per an event and time resolution for cosmic ray muon detection were systematically recorded throughout the experiment. It was observed significant degradation in the performance of RPC in which gas with water vapor was flown. Detailed studies were carried out to understand the causes and process of the degradation in performance of this RPC. These results will be presented.
The India-based Neutrino Observatory(INO) is a mega science project aimed at building a large underground laboratory to study the atmospheric neutrinos. 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. Study of the performance of RPC detectors of various glass samples is crucial to optimize the parameters of the ICAL RPCs. RPCs of dimension 30 cm × 30 cm are made with glass samples from different glass manufactures and operated in avalanche mode with a gas mixture that consists of R134a(C2H2F4, 95.2%), Isobutane(C4H10, 4.5%) and Sulfur hexafluoride(SF6, 0.3%). We have studied the performance of these RPCs at the same ambient conditions. The study of the detector efficiency, noise rate and charge resolution will be reported. We have observed that the operating high voltage varies from 10 kilo volt to 13 kilo volt for the RPCs made of different glass samples. To investigate further, we have fabricated RPCs with different glass thickness and studied in detail it's performance in the same ambient conditions. Detailed results will be presented in the conference.
The Resistive Plate Chamber (RPC) detector system at the Compact Muon Solenoid experiment at the LHC confers robustness and redundancy to the muon trigger. A total of 1056 double-gap chambers cover the pseudo-rapidity region |η|≤1.6 . All ancillary system (high voltage, low voltage, environmental, gas, and cooling) are constantly and closely monitored to achieve operational stability and high quality data in the harsh conditions of the second run period of the LHC (√s = 13 TeV and 25 ns bunch spacing). Data from these ancillary systems are stored in the online database in order to analyze and tune detector performance. First results of overall detector stability with 2015 data and comparisons with data from the first LHC run period (√s = 8 TeV and 50 ns bunch spacing) are presented.
INO/ICAL pilot experimental set up is running at TIFR,MUMBAI . Large area glass RPC detectors are under test on a continuous basis. The detector stack has capacity of 12 glass RPCs of maximum 2m x 2m size , connected in parallel . RPCs are continuously purged individually, with gas mixture of R134a , Isobutane and Sulphur Hexafluoride at a steady rate of 6 SCCM to maintain one volume change a day. To economize gas mixture consumption and to reduce the effluents from being released into atmosphere, a close loop system has been designed, fabricated and installed at the INO Lab in TIFR. This is unit is running continuously for more than 4 years. The close loop gas re-circulation system uses a simple pumping system consisting of pneumatically operated positive displacement cylinders in tandem. The pressure control is achieved through fine bore capillaries by dynamic pressure loss. Pressure reducing valves are used as safety device . The pressure and flow rate in the loop is controlled by mass flow controllers and pressure transmitters. Pneumatically operated high purity valves control flow loops and isolate the detector stack in case of unsafe pressure transients. The control is achieved through Siemens 1214C series Programmable Logic Controller through its I/Os. Gas Leak rate of 5.7 X 10E-4 SCCM ,equivalent to leakage of less than 3 Litres of gas mixture every 60 days backfill interval, has been achieved . In the same interval nearly 520 Litres gas mixture has been recirculated. The efficiency is calculated at 99.4% . The pressure balance is maintained at differential of 2 millibar +/- 0.1millibar over 960 to 1010 millibar Absolute Atmospheric pressure. The performance and integrity of RPCs in the pilot experimental set up is being monitored to assess effect of factors such as periodic fluctuation and transients in Atmospheric pressure and temperature , room pressure variation , flow pulsations , uniformity of gas distribution and Power failures . Capability of Close loop gas recirculation system to respond to these changes is also studied. The conclusions from the above experiment are presented . Validation of first design considerations and subsequent modifications have provided improved guidelines for design of Engineering Module Gas system and Main Module gas systems.
Resistive Plate Chambers (RPC) made of both glass and bakelite plates are under test and characterization processes as part of the detail R&D work for the ICAL detector setup of India-based Neutrino observatory [1]. A uniform response from the whole chamber is an important requisite for large area coverage (∼ 100,000 m2 ) of the ICAL which along with the large mass (∼ 50 kiloton) will help to achieve statistically significant number of neutrino interactions. Therefore, a numerical simulation has been conducted to study the electric field configuration of the chamber which is the key factor in the detector response dynamics. In order to carry out a detailed numerical simulation, the RPC has been modeled with its components in realistic terms of dimension, material and artifacts. For example, the inner surfaces of the bakelite plates which enclose the gas volume of RPC have been found to exhibit roughness of the order of 2 μm with standard deviation of about 350 nm. Asperities are also observed around the junctions of button spacers and electrodes due to leakage of glue. The desired uniform electric field within the gas volume of RPC is expected to be modified locally due to presence of these surface features, which will eventually affect the response from the detector. In the present study, the complex surface topology has been modeled using different statistical distributions of asperities of different shapes and sizes and their effect on the field map has been simulated. The calculations have been performed using COMSOL Multiphysics [2], a software based on finite element method and neBEM [3], a field solver based on boundary element method. Preliminary results on the effect of rough surface on the RPC response will be presented in the workshop. References: [1] ICAL collaboration, arXiv:1505.07380, 27/05/2015. [2] COMSOL : a multiphysics simulation tool, www.comsol.co.in [3] N. Majumdar and S. Mukhopadhyay, 2007 JINST 2 P09006.
Two barometric pressure sensor is used to measure both pressure and temperature of the atmosphere and inside of the RPC. These sensors sensor have an accuracy of 0.06hPa (0.6mmWC). After pressurizing the RPC, pressure difference between inside and outside is monitored for over 24 hours. One measurement sample is take in each 5 seconds and send over UDP packets to a computer and plotted immediately so that it can be seen from anywhere in real time. The differential pressure of a conventional manometer is highly dependent on pressure of the outside atmosphere. So it is not easy to track the leakage of a RPC for long period. But the absolute pressure readings of outside and inside RPC are independent, so, the difference between these two does not depend on the outside pressure, depends on the temperature only. So, by monitoring the pressure difference and the temperature, the leakage can be detected. During the monitoring, if there is any button-pop event, then it can be detected clearly and easily with the sudden fall of inside pressure up to 4-5mmWC.
The end-cap Time-of-Flight (E-TOF) system of Beijing Spectrometer (BESIII) is now upgrading based on the Multi-gapResistive Plate Chamber(MRPC) technology. The beam test for the MRPC prototype, together with the custom-designed Front End Electronics (FEE) and TDC boards, shows a time resolution of better than 50 ps. The final version of trapezium MRPC module has 2×6 gas gaps of 0.22mm thick. The signals are picked up by 12 strips with different length and read out from both ends of each strip. BESIII end-cap ring will be fully covered by 2×36 trapezium MRPC modules. The mass production and test of whole modules are carried on the group in USTC. The test results show that the produced MRPCs’ have stable performance and meet the quality standard in mass production. In consideration of the correction from the muon momentum distribution and the statistical effects, a time resolution together with readout electronics of better than 60 ps can be achieved by the cosmic ray test.
The CMS experiment, located at the CERN Large Hadron Collider, has a redundant muon system composed by three different 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. During the first long shutdown (LS1) of the LHC (2013-2014) the CMS muon system has been upgraded with 144 newly installed RPCs on the forth forward stations. The new chambers ensure and enhance the muon trigger efficiency in the high luminosity conditions of the LHC Run2. The chambers have been successfully installed and commissioned. The system has been run successfully and experimental data has been collected and analyzed. The performance results of the newly installed RPCs will be presented.
A brief description and first preliminary results of the Efficiencies and Cluster Size measurements of the CMS Resistive Plate Chambers, will be presented inside the Gamma Irradiation Facility GIF++ at CERN. Preliminary studies that sets the base performance measurements of CMS RPC for starting aging studies.
We present the results of the simulation of a 10ˆ3−10ˆ4 mˆ2 sampling calorimeter, made of RPCs with analog readout and soil or concrete as aborber. This instrument, deployed at high altitude, would be able to measure cosmic rays in the energy range 1 GeV - 1 PeV, triggered by isolated or quasi-unaccompanied hadrons. A study of optimization of the geometry layout and the electronic readout design to improve the capability of reconstructing energy, size and direction of the hadron will be given.
We present the results of the simulation of a multi-gap RPC system, with electrodes suited to increase the RPC efficiency to detect sub-MeV photons. The use of new materials, as well as the layout optimization, provide improved sensitivity while preserving the robustness and the cheapness of the RPC approach. Details on the conversion probability, the opacity of the electrode and the overall detection efficiency will be given in this contribution. Preliminary yet promising results on the single photon angular resolution will be provided. PET-related applications will be also discussed.
New eco-friendly gas mixtures are being searched for use in RPC muon detectors of the CMS experiment at the CERN LHC collider. The search must be complemented by detailed studies of the interactions of candidate ecogases with materials utilized in RPC detectors. The strategy followed is two-fold, namely a static and a dynamic search. The static search is performed by comparing materials properties (by means of SEM-EDS, XPS, XRD, FTIR analyses) before and after exposure to candidate ecogases in standard operating Conditions. The dynamic search consists of sampling and analysis (mass spectrography, F- and Cl- sensors) of candidate ecogases as exhausted by detectors after operation in electric fields and irradiation conditions.
The Endcap Time of Flight of BESIII(Beijing Spectrometer III) was upgraded with the Multi-gap Resistive Plate Chamber (MRPC), and time resolution was required better than 100 ps. The cosmic ray test was carried out for the MRPC detectors gathered with the new designed electronics. In the cosmic ray test the construction quality and joint operation of whole detector system were checked, and the performance of the detectors could be guaranteed. During the test, the noise rate and time measurement method are examined specifically.
The BGOegg experiment located at SPring-8 Synchrotron radiation facility in Japan was started since April 2014. The main goal of the experiment is to study the photoproduction of hadrons from the interaction of high energy photon and several targets like carbon, liquid hydrogen. For the purpose of measuring the recoiled proton from the reaction p(γ,p)X, where X is a meson, we have built a large Time of Flight detector (ToF) system based on the Resistive Plate Chamber (RPC). The ToF-RPC system of BGOegg experiment contains 32 separated RPC chambers which are aligned to cover an area of 6.4m2 in the forward region. The development and the prototype testing of the detector have been finalized in 2013, we started the mass production in the beginning of 2014. After establishing a suitable calibration method, we have obtained the first physics data from RPC. The initial analysis of the data show excellent performance of RPC in the experiment in term of proton selection, proton velocity measurement. Since we do not have any other detectors which are effectively able to separate proton from other charged particles flying forward, RPC data become very important. Furthermore, A good measurement of the recoiled proton in the two-body reaction, p(γ,p)X, given by RPC is useful to recalibrate the initial photon energy measuring by a tagging counter. At RPC workshop 2016, we would like to report about the current working status of our RPCs, the benefits of using RPC at the BGOegg experiment. Other aspects like selecting recoiled proton in the extreme forward angle from several 2-body reactions, proton missing mass analysis obtained from RPC will also be presented.
The BGOegg experiment located at SPring-8 Synchrotron radiation facility in Japan was started since April 2014. The main goal of the experiment is to study the photoproduction of hadrons from the interaction of high energy photon and several targets like carbon, liquid hydrogen. For the purpose of measuring the recoiled proton from the reaction p(γ,p)X, where X is a meson, we have built a large Time of Flight detector (ToF) system based on the Resistive Plate Chamber (RPC). The ToF-RPC system of BGOegg experiment contains 32 separated RPC chambers which are aligned to cover an area of 6.4m2 in the forward region. The development and the prototype testing of the detector have been finalized in 2013, we started the mass production in the beginning of 2014. After establishing a suitable calibration method, we have obtained the first physics data from RPC. The initial analysis of the data show excellent performance of RPC in the experiment in term of proton selection, proton velocity measurement. Since we do not have any other detectors which are effectively able to separate proton from other charged particles flying forward, RPC data become very important. Furthermore, A good measurement of the recoiled proton in the two-body reaction, p(γ,p)X, given by RPC is useful to recalibrate the initial photon energy measuring by a tagging counter. At RPC workshop 2016, we would like to report about the current working status of our RPCs, the benefits of using RPC at the BGOegg experiment. Other aspects like selecting recoiled proton in the extreme forward angle from several 2-body reactions, proton missing mass analysis obtained from RPC will also be presented.
We present a systematic study of charge distribution dependency of CMS Resistive Plate Chamber (RPC) on gap thickness. Prototypes of double-gap with five different gap thickness from 1.8mm to 1.0mm in 0.2mm steps have been built with 2mm thick phenolic high-pressure-laminated (HPL) plates. The charges of cosmic-muon signals induced on the detector strips are measured as a function of time using two four-channel 400-MHz fresh ADCs. In addition, the arrival time of the muons and the strip cluster sizes are measured by digitizing the signal using a 32-channel voltage-mode front-end-electronics and a 400-MHz 64-channel multi-hit TDC. The gain and the input impedance of the front-end-electronics were 200mV/mV and 20 Ohm, respectively.
The recently approved HL-LHC project and the future colliders proposals present a challenging experimental scenario, dominated by high pileup, radiation background and a bunch crossing time possibly shorter than 5 ns. This holds as well for muon systems, where RPCs can play a fundamental role in the design of the future experiments. The RPCs, thanks to their high space-time granularity, allows a sparse representation of the particle hits, in a very large parametric space containing, in addition to 3D spatial localization, also the pulse time and width associated to the avalanche charge. This 5D representation of the hits would increase the discovery potential of the experiment by allowing a better track pileup rejection and sharper momentum resolution, an effective measurement of the particle velocity, to tag and trigger the non-ultrarelativistic particles, and the detection of local multiple tracks in close proximity without ambiguities. Moreover, due to the fast response, typically for RPCs of the order of a few ns, this information can be provided promptly to the LVL0 trigger. In this talk, we will discuss the detector performance and the impact on physics of the Phase-1 and Phase-2 upgrades of the ATLAS RPC system. The design of these upgrades is already compatible with the 5D tracking concept, by implementing the latest generation of large area RPC technology and front-end electronics.
High pseudo-rapidity region of CMS muon system is covered only by Cathode Strip Chambers (CSC) and lacks redundant coverage despite the fact that it is a challenging region for muons in terms of backgrounds and momentum resolution. In order to maintain good efficiency for the muon trigger in this region additional RPC are planned to be installed in stations RE31 and RE41. The stations will use RPCs with lower granularity but good timing resolution to mitigate background effects and complete the redundancy of the system. R&D activities will be presented in the talk.
High resolution timing for muon detectors are potentially very important for experiments at future colliders. The brief interbunching time and the very high luminosity impose for detectors high perfomances in terms of intrinsic time and spatial resolution. In this work it is shown a comparison of different technologies for muon spectrometer focusing on peculiar performances of a new generation of RPCs.
The effort to redesign the RPCs for the future experiments muon systems has started shortly after the beginning of the LHC experiments and recently centered the goal of producing a 100 x 50 cm2 size prototype. This prototype inherits from the present ATLAS muon trigger chambers the basic design and simple construction features and bi-dimensional strip readout, but is equipped with a newly designed 1 mm gas gap with 1.2 mm HPL electrodes with a resistivity of about 1x1011Ωcm. An highly sensitive front end electronics, working with just 103e− of noise has been embedded directly in the RPC faraday cage, within the thickness of the readout panels. The combination of high sensitivity, large dimension and bi-dimensional readout represents a major challenge in building the prototype with specific reference to the Faraday cage structure. The result was such that the settable threshold is limited just by the intrinsic electronic noise, even in extremely noisy environment, such as the beam facility H4 of CERN, where the prototype has been tested with the GIF++ 137Cs photons and a muon beam. In this talk we will present the chamber performance operated at full efficiency in presence of a photon induced counting rate of the order of 10 kHz cm−2, notwithstanding the relatively high electrode resistivity.
Many experiments use Resistive Plate Chambers operated in avalanche mode, as timing or tracking charged-particle detector. Monte-Carlo simulation of physical processes is an important tool for detector development as it allows to predict signal pulse amplitude and timing, time resolution, efficiency and so on. Simulations for RPC-like detector are not widespread, and most of the time they use distributions like the Polya which lacks some physical interpretation or overlook important physics processes. We present a full, fast and multi-threaded Monte-Carlo simulation for Resistive Plate Chambers, using existing and well tested libraries and framework. The procedure is based on the modelisation of the main physics processes occurring during an electronic avalanche initiated by through-going charged particle. We use a one-dimension model for the avalanche development extended by the inclusion of radial diffusion and space charge effects which are of capital importance concerning the simulated charges production and saturation inside a RPC. This "hybrid" model is a compromise between the execution-speed of a 1D simulation and the accuracy of a 2D model. This simulation is well suited for study of single-gap RPC, and can be used for basic study of multi-gap RPC by simply piling up several single-gap geometries. It was also developed to be portable, modifiable and usable on various hardware and can be easily integrated into a global simulation of a detector chain.
The ICAL (Iron CALorimeter) set-up at India-based Neutrino Observatory (INO) [1] will use a large number of Resistive Plate Chambers (RPC) as the active detector element which will be stacked one above the other with alternate iron layers. The timing and spatial information from the RPCs will help determining the track of a muon produced from the interaction of atmospheric neutrino with the iron for obtaining its energy, charge and directional information. The presence of the inherent geometrical components like button and edge spacers, corners may affect the efficiency (already observed experimentally [2]) as well as timing properties of the RPC since the electric fields in the close vicinity of these regions have been found to differ from the otherwise uniform value inside the chamber [3]. In the present study, the effect of spacers and corners on the time resolution of RPC have been calculated numerically treating the resistive plates as perfect dielectrics with zero conductivity and the medium resistive coating as perfect conductor. Garfield [4] framework has been used for the study which uses neBEM [5], a field solver based on boundary element method, to generate the field map, MagBoltz to calculate the electron transport properties in a gaseous medium and HEED to calculate the primary ionization due to passage of a charged particle. The field map has also been calculated using COMSOL [6], which uses finite element method and the results have been compared with that from neBEM. Thousand muons, each of energy 2 GeV, have been passed through a bakelite RPC at an angle 14.5∘ with the axis of the chamber and the time taken by the electrons, produced in the gas ionization to reach the RPC plate has been filled in a histogram. The standard deviation of the histogram gives the time resolution of the RPC. A gas mixture of R134-A, Isobutane and SF6 has been used for this study in a ratio 95.0 : 4.5 : 0.5. The time resolution has been found to be about 0.32 ns, which is fairly close to the value found in experiments (1 - 2 ns). The same will be evaluated at the critical regions to study the effect of different geometrical components like corners and spacers. It is also planned to include the spatial and energy distributions of the passing muons in the calculation. The relevant results will be reported in the workshop. References : [1] ICAL collaboration, arXiv:1505.07380, 27/05/2015. [2] M. Bhuyan et al., Nucl. Instrum. Meth. A 661 (2012) S68. [3] A. jash et al., Springer Proceedings in Physics, ISBN 978-3-319-25619-1 (accepted). [4] Garfield - simulation of gaseous detectors, http://garfield.web.cern.ch/garfield [5] N. Majumdar and S. Mukhopadhyay, 2007 JINST 2 P09006. [6] COMSOL : a multiphysics simulation tool, http://www.comsol.co.in
We present a simple yet powerful emulation software, devised to compute waveforms from few structural parameters of the Resistive Plate Chamber. In the first emulation step, the core algorithms are based on some simplified hypotheses, both for the space-time dependence of the local electric field and for the readout equivalent circuit. (Initially) Indeed setting the gap width, the primary ionization, the drift velocities and the effective readout capacity allows rapidly computing thousands of waveforms, whose features can be compared with the experiment. Further studies are also possible by exploiting the interfaces to more sophisticated external packages simulating the primary interaction with matter, the plasma evolution in the gas gap, the full 3D-time evolution of the electric field and the readout electronics. Remarkably, the software can also be used to extract the value of the few equivalent parameters from any given set of experimental waveforms, helping to use the RPC as a tool to study electrical phenomena in gaseous media. Features and possibilities of the software will be shown, as well as results from the ongoing process of experimental validation.
The BESIII detector runs in the tau-charm physics energy region operated at the Beijing Electron Positron Collider (BEPCII). The endcap of its time-of-flight (TOF) subdetector is planned to be upgraded with MRPC. We installtwo testing MRPC modules into BESIII and have collected some experimental data under various high voltage and thresholds. A GEANT4-based Monte-Carlo model is under development. Here we study the simulation performance under different high voltages and thresholds and compare it with the experimental data in the aspects of time resolution and efficiency.
After the upgrades of the Large Hadron Collider (LHC) planned for the second and the third Long Shutdown (LS), the LHC luminosity will approach values like 5×10ˆ34cmˆ−2sˆ−1. Such conditions will affect the performance of the CMS muon system, especially in the very forward region, due to the harsh expected background environment and high pile-up conditions. The CMS collaboration considers upgrading the muon forward region to take advantage of the pixel tracking coverage extension a new detector, ME0 station, possibly behind the new forward calorimeter. New resistive micro-pattern gaseous detectors that are able to handle the very demanding spatial, time resolution and rate capability, are being considered. In this contribution we introduce a new type of MPGD technology: the Fast Timing Micro-pattern (FTM) detector, utilizing a fully resistive WELL structure. It consists of a stack of several coupled layers where drift and WELL multiplication stages alternate in the structure, yielding a significant improvement in timing properties due to competing ionization processes in the different drift regions. Two FTM prototypes have been developed so far. The first one is micro-WELL-like, where multiplication takes place in the holes of a kapton foil covered on both sides with resistive material. The second one has a resistive structure with multiplication developing in a region delimited by a resistive mesh. The structure of these prototypes will be described in detail and the results of the characterization study performed with an X-Ray generator will be presented. The first results on rate capability and time resolution based on data collected with cosmic rays and beam tests will also be presented.
Searches for new physics with accelerators are being performed at the LHC, looking for high massive particles coupled to matter with ordinary strength. A new experimental facility meant to search for very weakly coupled particles in the few GeV mass domain has been recently proposed at CERN. The existence of such particles, foreseen in different theoretical models beyond the Standard Model, is largely unexplored from the experimental point of view. A beam dump facility, built at CERN in the north area, using 400 GeV protons is a copious factory of charmed hadrons and could be used to probe the existence of such particles. The beam dump is also an ideal source of tau neutrinos, the less known particle in the Standard Model. We report the physics potential of such a facility and the technology choices of its detector. In particular, Resistive Plate Chambers are a viable technology for the muon spectrometer of the tau neutrino detector.
One of the solutions proposed for the start time and reaction plane determination in the CBM experiment is the Beam Fragmentation T0 Counter. This detector will be located at the forward region where the particle fluxes are expected to reach 2.5x105cm−2s−1. Therefore, ceramic RPCs with floating electrodes of low bulk resistivity will be used due to their high rate capabilities. A single RPC cell consists of double-gap stacks, where the outer electrodes are high resistive Al2O3 ceramics with a Chromium layer deposited on them and the floating electrodes are made of low resistive Si3N4/SiC ceramics. A complete module is formed by three such cells (2x2cm2 or 5x5cm2) forming a six-gap RPC. The edge zones of the electrodes are grooved with a Rogowski cross section. This effectively reduces the dark current of the detectors and allows to operate them with higher electric field strengths. The usage of Isobutane free gas mixtures is mandatory for a long detector lifetime. A couple of modules were assembled and exposed with relativistic electrons at ELBE (HZDR) where a beam flux of up to 1.5x105 cm-2 s-1 was used, and with pions at the T10 beam-line (CERN). In both tests a detection efficiency of 98% was achieved. The next steps will be the commissioning and investigation of a multi-module prototype.
The High Luminosity phase of LHC, foreseen to start in less then ten years from now, has triggered the development of a new generation of gaseous detectors with much improved performance with respect to the present one. For what concerns Resistive Plate Chambers, R&D is focusing on the methods to increase the maximum flux of impinging particles that these devices can stand without degradation for a prolonged -up to more than ten years- period of time. Different solutions are being proposed and extensively investigated upon. Here a detailed overview of the physics that governs the processes taking place in RPCs at high rate will be presented. The fundamental parameters that influence rate capability will be taken in exam and the way how they can be optimized in order to increase rate capability will be outlined. A comparison with simulation and experimental data confirms the goodness of the approach and the validity of results obtained.
We report on a systematic study of double-gap and four-gap phenolic resistive plate chambers (RPCs) for high-η RPC triggers in CMS. Prototype double-gap and four-gap RPCs with gap thicknesses of 1.6 and 0.8 mm, respectively, have been constructed with 2-mm thick phenolic high-pressure-laminated (HPL) plates. Two different type front-end-electronics (FEE) were used for the digitization of the detector signals; charge-sensitive FEE for the operation of the current double-gap CMS RPCs and higher sensitive voltage-sensitive FEE dedicatedly developed for the fundamental study of RPCs. The prototype RPCs were measured for cosmic muons and gamma rays emitted from a 5.5 GBq 137Cs source. The gamma-signal rates induced in the double-gap and four-gap RPCs installed at a distance of 36 cm from the cesium source ranged from 0.6 to 1.5 kHz cm-2. The muon cluster sizes and the probabilities of occurring large multiplicity were sensitive to the choice of digitization threshold for both type RPCs while the efficiencies were relatively less sensitive. For the double-gap RPCs, better detector characteristics were obtained at the higher digitization threshold. For the four-gap RPCs, on the other hand, choice of the low thresholds will be fairly conducive to suppress the detector current induced by high-rate backgrounds.
To improve the muon trigger efficiency of the high eta region of the CMS experiment and to cope with the expected luminosity increase in the second phase of the LHC, new RPC detectors using low-resistivity materials are proposed to equip part of the high-eta region. Several beam tests at DESY and CERN have shown that new detectors using low resistivity glass (of less than 1010 Ω.cm) could stand particle rates of few kHz/cm2 in its single-gap version and few tens of KHz/cm2 in its multi-gap version. Test of several months at GIF has confirmed the robustness of such detectors and new tests in the new GIF++ facility are planned to complete the study. In parallel the excellent timing the RPC and MRPC could provide will be exploited by developing a new low-noise ASIC equipped with precise TDC device.
MRPC prototypes with readout on a multi-strip electrode were developed for the most demanding zone of the CBM-TOF wall, small polar angles region. The prototypes are based on low resistivity glass (~10^{10} Ohmcm). The granularity, given by the strip pitch size and strip length was chosen such to cope with the high values of the counting rates and multiplicities anticipated for the innermost zone of the CBM-TOF wall. Results of the in-beam test using secondary particles produced by a heavy ion beam incident on a lead target at SIS18 - GSI Darmstadt and SPS - CERN, focused on the performance of the prototype in conditions close to the ones expected for their operation in the CBM TOF wall at SIS100/FAIR, will be presented.
MRPC has been widely used in many nuclear and particle physics experiments for its good time and efficiency performance. With the increasing of accelerator luminosity, high rate MRPC with large area will be a promising updater in many experiments. Compact Muon Solenoid (CMS) experiment intends to use MRPC technology to upgrade the end-cap muon system. The low-resistive glass developed by Tsinghua University can be used to construct high rate MRPC and the rate capability can excess 25 kHz/cm2. But, there is also a challenge that the size of the glass is limited by the production technology. We initially designed a large mosaic MRPC. 0.5mm-diameter fishing line is used to separate two pieces of glass to prevent sparks. An electric field simulation has been processed, the results show that only 0.1\% of the detector is affected by 0.5mm separator, and this area still has an efficiency high than 80\%. Cosmic ray tests show that the efficiency can reach 94.6\% and the resolution around 74ps. This detector is also tested with 40 MeV electrons beam at Helmholtz-Zentrum Dresden-Rossendorf (HZDR). Similar results have been got. The efficiency is nearly 95\%. The MRPC’s efficiency is still 90\% when the beam intensity reaches around 40 kHz/cm2. The efficiency loss at the joint area is less than 2\%. Based on this technology, a large area trapezoidal MRPC will be constructed for CMS muon system. Analysis results show that muon system with good time resolution can reduce background greatly. presentation type: oral
ALICE is the LHC experiment dedicated to the study of heavy-ion collisions. At forward rapidity a muon spectrometer detects muons from low mass mesons, quarkonia, open heavy-flavor hadrons as well as weak bosons. A muon selection based on transverse momentum is made by a trigger system composed of 72 resistive plate chambers (RPC) for a total of ∼140 m2 of active surface and almost 21000 channels. For the LHC Run 1 and the ongoing Run 2 the RPCs have been equipped with a non-amplified FEE called ADULT. However, in view of an increase in luminosity expected for Run 3 (2021--2023) the possibility to use an amplified FEE has been explored, in order to improve the counting rate limitation and to prevent the aging of the detector by reducing the charge per hit. Considering the peculiar specificities of the project, a prototype of this new electronics (FEERIC) has been developed and tested first with cosmic rays before equipping one RPC in the ALICE cavern with it. In this talk the most important performance indicators (such as efficiency, dark current, dark rate, cluster size, integrated charge and charge per hit) of the RPC equipped with this new FEE will be presented and compared to those obtained with ADULT, in pp collisions at s√=13 TeV and in Pb--Pb collisions at sNN‾‾‾‾√=5 TeV.
Abstract: Multi-gap Resistive Plate Chamber (MRPC) is a new type of gas detector developed on the base of RPC and it has been applied in many large hadrons experiments to construct time of flight system. Compared with other gas detector, MRPC has relatively narrow gasp gap and its performance is strongly dependent on gas quality. With accelerator luminosity continually growing in recent years, gas quality, related with particle intensity, has become a more and more important factor for gas detector. Such gas pollution effect has been observed on RHIC-STAR muon telescope detector (MTD), where the noise and dark current keep increasing for a very long time after the MTD worked under a relatively higher luminosity physics condition. The time-of-flight (TOF) wall of CBM, proposed to be constructed with MRPC, will work at very high rate (~25kHz/cm2) environment. The gas pollution remains a very important aspect we have to study. We’ve conducted a series of experiments on gas pollution with a 50cm x 50cm 8-gap MRPC. A high intensity X-ray source is used to simulate high particle flux condition and the current recovery time is involved for measuring the extent of gas pollution. The preliminary results show that influence of gas pollution has grown stronger with the increase of the gas box’s volume or the decrease of gas flow rate. To study the volume effect in detail, a self-sealing MRPC with the same 8-gap structure has been developed. The detector works in good condition and 95% of efficiency is obtained in cosmic-ray test. When tested with X-ray irradiation, self-sealing MRPC’s current recovers faster than normal MRPC. This means that the self-sealing structure can improve the gas exchange speed in the chamber. At the same time, a simulation of hydrodynamics based on the SIMPLE-2D method is carried out, intending to confirm the relation between gas pollution and volume. We’ve got the same rule as in the experiment that the maximum concentration of polluted gas grows stronger when MRPC is held in a larger-size flowing volume. All of these shows that the gas pollution is a severe effect at high luminosity experiments, and further study can help us to reduce this effect in the design of CBM-TOF system. (Presentation type: oral)
In this talk we present the status of the HZDR laser test facility for investigation of gas parameters in micro-gap structures at high electric fields (up to 100 kV/cm) and normal pressure. This facility has the unique characteristic of using the UV radiation as instigator of a gas primary ionization in a well-defined micrometer-sized volume. The results of several three-component gases consists of iso-butane/SF6/iC4H10 will be discussed. Simulation of RPC probes with the same geometries, gas mixtures and electric fields according to the experimental setup was performed within the Garfield++ framework. A comparison of the simulation and experimental data is given. Furthermore, the current upgrade status of the facility to a higher precision and automated acquisition is explained.
RPCs operated in streamer mode are still a detector of potential interest in neutrino and astro-particle physics applications (like OPERA and ARGO experiments). Such experiments are typically characterized by large area apparatuses with no stringent requirements on detector aging and rate capabilities. More than 40 gas mixtures obtained by combining 10 different gases have been tested using cosmic rays and digitizing the RPC signals at 5 GSamples/s. Mixtures containing "ecologic" HFO-1234ze and HFO-1234yf isomers have been also tested in order to optimize their concentration. The introduction of HFO-1234ze is helpful also because removing the flamable iso-butane from the mixture, safety requirements are much simplified. The results of the tests will be presented both in terms of detectors properties (efficiency, multiple-streamer probability and time resolution) and in terms of streamer characteristics.
The RPC performance is strongly dependent on the material used for the resistive electrodes. It must combine indeed an electrical resistivity adequate to the expected operation rate with a good mechanical strength to insure the gas gap uniformity. New materials are considered and some experimental results at cosmic ray rates are presented
The development of low resistivity material to increase the rate capability of the RPC has been attracting more and more attention recently. We present here a new type of such a material. The new material is based on the polyimide doped with carbon. The electrical volume resistivity of this material could be controlled using different percentage of the doping carbon. The standard thickness of polyimide carbon films is around 40 um which does not allow to use it as such to build the RPC electrodes. To overcome this we developed a new stress method to make the gap between two polyimide carbon films. In this paper we will introduce the new detector material, the new type of RPC and the cosmic bench test results. In the future lager area of RPC will be made and the different characteristics will also be tested.
The India-based Neutrino Observatory (INO) collaboration has proposed to build a 50kton magnetized Iron Calorimeter (ICAL). Main aims of this experiment are to precisely measure the atmospheric neutrino oscillation parameters and to determine the ordering of neutrino masses. The collaboration has chosen Resistive Plate Chambers (RPCs) made up of float glass electrodes of 1.9 m × 1.8 m in area as the active detector elements and is going to deploy about 28,800 of them in the ICAL detector. Operation and the performance of RPC detector are known to mostly depend on the surface quality, bulk, and electrical properties of the electrode materials. Since ICAL is going to deploy RPC detectors in an unprecedented scale, it is imperative that we study these aspects in detail. Therefore, systematic characterization studies on the glass samples from various manufacturers have been carried out in order to arrive at a better understanding on the choice of electrodes for long term operation of RPCs. Results of these studies will be presented.
A new Gamma Irradiation Facility (GIF++) to test detectors for the HL-LHC program is available at CERN and has started to be operational in 2015. This is a unique place where high energy charged particle beams (muon beam with momentum up to 100 GeV/c) are combined with a 14 TBq 137 Cesium source. The increase in luminosity at the HL-LHC will produce a higher particle background and the effects integrated over a long period of time will present a new challenge for particle detectors. Preliminary CMS Resistive Plate Chambers performance and stability results at the new GIF++ facility will be reported. Aging studies plans for the CMS RPC system will be also discussed.
The operations of Resistive Plate Chambers in LHC experiments require F-based gases for optimal performance. Recent regulations demand the use of environmentally unfriendly F-based gases to be limited or banned. In view of the CMS experiment upgrade several tests are ongoing to measure the performance of the detector in terms of efficiency, streamer probability, induced charge and time resolution. Prototype chambers with readout pads and with the standard cms electronic setup are under test. In this talk preliminary results on performance of RPCs operated with a potential eco-friendly gas candidate 1,3,3,3-Tetrafluoropropene, commercially known as HFO-1234ze and with CO2 based gas mixtures are presented and discussed for the possible application in the CMS experiment. Files
Further gas mixtures with low envoirment impact have been tested. For the best RPC performance the main effort was to look for a mixture giving a confortable separation between avalanche and streamer and a gas density ensuring sufficient primary ionization. The measurements have been carried out on small size chambers at cosmic ray rates using the waveforms recorded on the oscilloscope. Efficiencies and distributions of amplitude and charge will be presented.
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 Freon-based gas mixture containing C2H2F4 (R134a), SF6 and iC4H10. The first two gas will be phased out from production in the near future due to their high global warming potential (GWP). Even if R134a and SF6 will always be available for research purposes, their cost can increase as the interest of industry and marker will decrease. Therefore, the search of new environmental friendly gas mixtures is advisable for reducing GHG emissions, costs as well as to optimize RPC performance and possible aging issues. Several hydrofluorocarbons (HFCs) and hydrofluoroolefins (HFOs) with a global warming potential lower then the C2H2F4 have been studied as possible replacement. New environmental friendly gas mixtures based on these gases with the addition of inert components have been tested on single-gap RPCs by measuring the detector performance in terms of efficiency, streamer probability, induced charge, cluster size and time resolution. Evaluations of the quenching and electronegative capacities of the selected eco-friendly gas candidates have been deduced by comparison of the RPC performance. Operation in streamer mode is easily achievable using HFO-1234ze with the addition of Ar, while the avalanche regime requires further studies since both HFO-1234ze and HFO-1234yf behave very differently from C2H2F4. However, encouraging results of RPC operation in avalanche mode have been obtained with 4 and 5 components gas mixtures.
The availability of proton and ion beam therapy is increasing every year. A precise radio oncological treatment demands the knowledge of the dose distribution in human tissue. Energetic hadrons interact with tissue and generate prompt gamma rays with energies of up to 10 MeV. The prompt photons provide information about the hadron beam exposure. We investigated the usage of resistive plate chamber (RPC) detectors for such an application. The detection prompt photon efficiency of the RPC has been simulated. We found a value of 2% per gas gap. Two multi-gap RPCs with different electrodes (soda limed glass and Si3N4/SiC) have been tested in a Bremsstrahlung beam generated with 13 MeV electrons delivered by the ELBE accelerator at the Helmholtz-Center Dresden-Rossendorf (HZDR), thus approaching therapy conditions. A LaBr-scintillation counter monitored the photon rate. First results of the RPC efficiency and time resolution in dependence on the photon flux will be presented.
The muography is an imaging technique for large and dense structures as volcanoes or reactors using atmospheric muons. We applied this technique to the observation of the Puy de Dôme, a volcano 2 km wide close to Clermont-Ferrand. The detection is performed with a 1m×1m×1.80m telescope made of 4 layers of single gap glass-RPCs. The 1cmˆ2 pad readout uses the Hardroc2 ASICs. The three data taking campaigns over the last three years showed that a RPC detector can be operated in-situ with good performances. Further developments to decrease the power consumption and to improve the position and timing resolution of the detector are ongoing.
We are developing a positive ion detector with single ion sensitivity for radiation track structure characterization [1]. The device combines the operational principles of thick gas electron multipliers (THGEM) [2], working in reverse polarity, and resistive plate chambers (RPC). As shown in figure 1, ions produced in a low pressure gas volume drift towards a THGEM-like structure made of a single side-clad dielectric plate provided with holes of millimetric dimensions. On the other side of the plate, a high resistivity cathode connected to a negative high voltage is used to generate a high restricted field across the hole structure. Positive ions focused into the holes are accelerated and produce ion-impact ionization of the working gas, which develops into a controlled discharge. The discharge is confined in time due to the high volume resistivity of the cathode and in space by walls of the holes in the dielectric plate. Because of the high electron gain, the signal induced in the readout electrode can be acquired with standard electronics. Moreover, using a 2D readout strip configuration, coordinates of the holes generating the signal can be reconstructed, which, together with a drift time measurement, allows a 3D reconstruction of charged particle tracks formed in the working gas. This device has possible applications in radiobiology. The spatial distribution of ionization events within biological targets of nanometric dimensions (e.g., DNA) is strongly correlated with the biological effectiveness of ionizing radiation. By comparing the track structure of different radiation qualities, the difference in their biological effect at equal absorbed doses can be studied. The use of a working gas pressure of the order of a few millibars allows experimental simulation of the radiation interaction with nanoscopic biological targets by expanding condensed matter dimensions up to a million times. Monte Carlo simulations show that by using tissue equivalent gases and appropriate volume scaling factors equivalent ionization spatial distribution can be obtained in gas and water [3]. Initial measurements with a detector prototype filled with propane gas revealed low ion detection efficiency, of the order of a few percent [4]. A thorough detector characterization showed that both low ion-impact ionization probability and long detector dead time due to the long recovery of the electric field in the hole after the discharge impacted the detector performance. In order to tackle the first issue, a study of detector efficiency as a function of dielectric plate thickness was performed. Measurements with detectors made of a few holes in polystyrene plates ranging from 3 to 10 mm in thickness showed that efficiency increased with hole height. Different cathode materials were tested in order to reduce the detector dead time. When a semiconductive glass cathode with volume resistivity of the order of 10ˆ12Ω⋅cm was used rather than a standard glass cathode, the detector efficiency improved. Additional effort has been made minimizing spurious discharges that increase dead time. In particular, in the latest detector design the cathode is excluded from the low pressure environment, and the PCB board manufacturing has been commissioned to the CERN PCB workshop in order to minimize manufacturing imperfections of holes and readout electrodes. Further, the possibility of using a slightly conductive glass GEM to avoid charge-up effects and decrease dead time is under study. We conclude that, while preliminary results are promising, additional work is necessary to improve the ion detector performance in order to build a versatile 3D radiation track structure detector. References: 1. Bashkirov V. A., Hurley R. F. and Schulte R. W. A novel detector for 2D ion detection in low-pressure gas and its applications. In: NSS/MIC Conference Record, IEEE, pp. 694–698, (2009). 2. Chechik R., Breskin A., Mörmann D. and Shalem C. Thick GEM-like hole multipliers: properties and possible applications. Nucl. Instr. Meth. A535, 303 (2004). 3. Grosswendt B. Nanodosimetry, from radiation physics to radiation biology. Radiat. Prot. Dosim. 115, 1–9 (2005). 4. Casiraghi M., Bashkirov V., Hurley F. and Schulte R. A novel approach to study radiation track structure with nanometer-equivalent resolution. Eur. Phys J. D 68, 111 (2014). ---------- Figure 1: Schematic representation of the single ion detector design. From top to bottom: copper anode providing the drift field (Ed) through the sensitive volume, PCB board with 2D hole-array and readout electrode, high-resistivity cathode providing the accelerating field (Ea) in the holes.
Cosmic ray muon tomography is a novel technology for high-Z material detection with high penetration and intrinsic safety feature. Several muon imaging facilities had been setup all over the world based on different types of detectors, such as drift tube, drift chamber, GEM, RPC, scintillator and so on. We have been studied muon technology for many years and a prototype of Tsinghua University cosmic ray MUon Tomography facilitY (TUMUTY) was set up in our laboratory. In order to get the energy information of incident muons, MRPC is used as track detector and its signal is amplified with fast current amplifier. 5GHz waveform digitizer is used to record the pulse shape. A kind of large area MRPC with high position resolution is studied. The dimension is 1160mm×1160mm and it consists of six gaps and the width of gap is 0.25mm. The counter has 422 1.44mm read out strips with 1.1mm gap between strips (the width of the pitch is 2.54mm). 98% efficiency is obtained in cosmic test. We also measured its spatial resolution by an X ray source with a narrow slit, the position resolution is around 367µm. In this paper, we introduce the development of detector, and we also discuss the cosmic test and X-ray test. The results of test kits by TUMUTY are also described. Rresentation type:Oral