Bakelite Resistive Plate Chambers Research Articles

Measurements of fluoride production in Resistive Plate Chambers

Resistive Plate Chambers (RPCs) are operated with a gas mixture made of C2H2F4, SF6 and iC4H10. It is well known that under the effect of a high electric field and radiation, the C2H2F4 molecule breaks into several compounds and free fluoride ions, which can accumulate under gas recirculation and could be harmful for the long-term detector operation. Furthermore, if High Pressure Laminate (HPL) electrodes are employed, the gas mixture is humidified and, in presence of water, the free fluoride ions become hydrofluoric acid (HF), a very reactive compound. The F− production depends on several factors such as radiation rate, gas flow, detector current and gas mixture. In this study we developed and tested two different set-ups for the F− concentration measurements by using an Ion Selective Electrode (ISE) station. The measurement on the F− production were performed on 2 mm gas gap bakelite RPC detector irradiated at the CERN Gamma Irradiation Facility (GIF++) with different absorption factors. Several gas mixtures were tested to understand how the formation of HF is affected. The F− production of the standard gas mixture was compared with the one of the standard gas mixture with the addition of 30% CO2 at several gamma rates. Different concentrations of SF6 were also investigated to understand if and how the SF6 could affect the F− production. Finally, two gas mixtures containing HFO1234ze, C2H2F4 and He or CO2 were used to study the RPC F− production in presence of the HFO1234ze, which is less stable in atmosphere with respect to the C2H2F4.

Test and characterisation of STS/MuCh-XYTER and integration with multiple detectors of CBM-MuCh detector systems

Compressed Baryonic Matter (CBM) is a fixed target experiment at the upcoming Facility for Anti-proton and Ion Research in Germany, having collision rates up to 10 MHz. Due to the proximity of the target and secondaries produced in absorbers, Muon Chambers (MuCh) of the CBM experiment will face a very high particle hit rate of up to 400 kHz/cm2 in its first two stations. To cope with these particle rates, a Gas Electron Multiplier (GEM) detector will be used for the first two stations while, due to relatively lower particle rates, the last two stations will use a low resistivity Bakelite Resistive Plate Chamber (RPC) detector. The electronics of these two MuCh detectors need different dynamic ranges.A Silicon Tracking Station (STS) system made of 300 μm thick silicon micro-strip sensors will be installed upstream of the MuCh detector system. The sensors will be read out through multi-line micro-cables with fast electronics. The micro-strip sensors will be double-sided with a stereo angle of 7.5°, a strip width of 58 μm, and strip lengths between 20 and 120 mm requiring high-density readout.To meet the high rate and high density requirements of MuCh and STS, respectively, a specialized 128-channel readout ASIC with a dual-gain feature is designed. This is a highly configurable ASIC with about 30,000 configurable register bits which control various bias and threshold settings of the ASIC. To integrate this ASIC with both the detector systems, detailed testing and characterization of the ASIC are required.Due to the high number of configurable registers and several operating conditions, characterizing this ASIC is very challenging. This paper describes the optimization procedures of several configurable bias parameters in detail and also explains how this ASIC is integrated with both GEM and RPC detectors of the MuCh system.

Characterization of a new RPC prototype using conventional gas mixture

Resistive Plate Chamber is a well-known gaseous detector in the field of High Energy Physics experiments for its good tracking capability, high efficiency, good time resolution, and low cost of fabrication. The main issue in Resistive Plate Chamber is its limitation in the rate handling capability. Several experimental groups have developed sophisticated techniques to increase the particle rate capability and reduce the noise rate of this detector. In bakelite Resistive Plate Chamber linseed oil coating on the inner electrode surface is done to get rid of surface roughness of the resistive electrodes. We developed a new method for linseed oil coating in case of bakelite Resistive Plate Chamber to achieve good efficiency (> 90%). In this article, we discussed the test results obtained from a prototype fabricated in this new method, using a conventional gas mixture.

A new technique of linseed oil coating in bakelite RPC and the first test results

Single gap Resistive Plate Chamber (RPC) is one of the very popular gaseous detectors used in high-energy physics experiments nowadays. It is a very fast detector having low cost of fabrication. The RPCs are usually built using glass or bakelite plates having high resistivity ∼1010–1011Ω cm. Bakelite RPCs are generally fabricated with a linseed oil coating inside to make the inner electrode surface smoother which helps to reduce the micro discharge probability. Linseed oil coating also reduces the surface UV sensitivity dramatically and effectively protect the bakelite surfaces from the Hydrofluoric Acid (HF), produced by the interaction of fluorine with the water vapour. There is a conventional way to do this linseed oil coating after making the gas gap as done in experiments e.g. ALICE, CMS etc. A new technique is introduced here to do the linseed oil coating on the bakelite plate before making the gas gap. 100% Tetrafluoroethane (C2H2F4) gas is used to test the RPC module in the avalanche mode with cosmic rays. Conventional NIM electronics is used for this study. The efficiency and noise rate are measured. In this article, the detailed method of fabrication and the first test results are presented.

Performance of a prototype bakelite RPC at GIF++ using self-triggered electronics for the CBM experiment at FAIR

The Muon Chamber (MuCh) is a sub-system of the Compressed Baryonic Matter (CBM) experiment for the detection of low-mass-vector mesons produced in high energy heavy ion collisions at beam energies ranging from 2 AGeV to 11 AGeV and decaying in the di-muon channel. MuCh consists of a segmented absorber and four detector triplet stations sandwiched between the absorber segments. At the 3rd and 4th stations of MuCh, Resistive Plate Chambers (RPCs) have been conceived for muon tracking. We have tested the performance of a low resistivity bakelite RPC prototype equipped with self-triggered front end electronics (MuCh-XYTER) for the CBM Muon Chamber. A systematic study on the muon detection efficiency and time resolution has been carried out in a high-rate photon background at the Gamma Irradiation Facility (GIF++) at CERN. The details of the measurement setup and the results are presented here.

R&D of gas filled detectors for high energy physics experiments


 
 
 Bose Institute is Asia’s first modern research centre devoted to interdisciplinary research and bears a century old tradition of research excellence. In the experimental high-energy physics (EHEP) detector laboratory of Bose Institute, Kolkata, we are working on the R&D of Gas Electron Multiplier (GEM), straw tube detector for future heavy ion physics experiments and also developing low resistive bakelite Resistive Plate Chamber (RPC), keeping in mind high particle rate handling capacity. The main goal of our research program is the stability study and ageing study of gaseous detectors mentioned above. In this review article, the details of the R&D program of GEM detector, straw tube and RPC detectors carried out during the last five years is reported. 
 
 

Gamma irradiation induced microstructural modification and electrical conductivity of bakelite resistive plate chamber material

Polymer-based Bakelite resistive plate chamber detector samples were exposed to 60Co gamma source for various irradiation doses. To explore the impact of gamma irradiation induced structural modifications, Positron annihilation lifetime, Fourier transform infrared spectroscopic and X-ray diffraction (XRD) studies were performed. The increased free volume (Vf) for lower irradiation doses is attributed to the scission of polymeric chains. The free volume parameters are in good agreement with XRD and conductivity results. The ac conductivity varies linearly with the applied frequency and obey Jonscher power law. The conduction mechanism is explained on the basis of barrier hopping model.

Intrinsic linearity of bakelite Resistive Plate Chambers operated in streamer mode

Abstract Resistive Plate Chambers have largely been used in High Energy Physics and Cosmic Ray research. In view of using this detector for calorimetry applications it is important to know the maximum measurable particle density, or its intrinsic linearity limit, which is tightly related to the dimension of the discharge region. In this paper we report the results of measurements performed at the Beam Test Facility (INFN National Laboratory of Frascati, Italy) where the intrinsic linearity of bakelite RPCs operated in streamer mode has been tested at different impinging particle densities.

Charge measurement of oil-free single gap Bakelite Resistive Plate Chamber

Resistive Plate Chamber (RPC) is a gaseous detector used in many particle physics experiments for the detection of the charged particle using the gaseous ionization process. The total charge produced by cosmic rays interacting with the gas atoms/molecules in the gas volume of a large-sized, single gap, oil-free bakelite RPC has been measured. In this manuscript, such measurements along with the gain of the detector at different operating voltages have been reported. At the optimized operating voltage of the detector i.e 9000 V, the mean value of the charge and the gain was measured to be ∼ 186 pC and gain ∼ 7.2 × 107 respectively.

Timing studies of oil-free bakelite multi-gap resistive plate chamber

The Multi-gap Resistive Plate Chambers (MRPCs) are parallel plate gas detectors known for their excellent time resolution. High precision in timing measurements makes these detectors suitable for Time-Of-Flight (TOF) studies in several experiments. We have developed two nearly identical oil-free bakelite MRPCs. The time resolution measurements of these detectors with cosmic rays have been reported here. • Multi-gap resistive plate chambers can be made with bakelite sheets without any oil coating. • Bakelite MRPCs also show good time resolution. • Induced charge in bakelite MRPCs also increases with increase in applied high voltage.

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.

Long term performance studies of large oil-free bakelite resistive plate chamber

Several high energy physics and neutrino physics experiments worldwide require large-size RPCs to cover wide acceptances. The muon tracking systems in the Iron calorimeter (ICAL) experiment in the India based Neutrino Observatory (INO), India and the near detector in Deep Underground Neutrino Experiment (DUNE) at Fermilab are two such examples. A single gap bakelite RPC of dimension 240 cm × 120 cm, with gas gap of 0.2 cm, has been built and tested at Variable Energy Cyclotron Centre, Kolkata, using indigenous materials procured from the local market. No additional lubricant, like oil has been used on the electrode surfaces for smoothening. The chamber is in operation for > 365 days. We have tested the chamber for its long term operation. The leakage current, bulk resistivity, efficiency, noise rate and time resolution of the chamber have been found to be quite stable during the testing peroid. It has shown an efficiency > 95% with an average time resolution of ∼ 0.83 ns at the point of measurement at ∼ 8700 V throughout the testing period. Details of the long term performance of the chamber have been discussed.

Study of RPC bakelite electrodes and detector performance for INO-ICAL

The Resistive Plate Chambers (RPCs) are going to be used as the active detectors in the India-based Neutrino Observatory (INO)-Iron Calorimeter (ICAL) experiment for the detection and study of atmospheric neutrinos. In this paper, an extensive study of structural and electrical properties for different kind of bakelite RPC electrodes is presented. RPCs fabricated from these electrodes are tested for their detector efficiency and noise rate. The study concludes with the variation of efficiency, leakage current and counting rate over the period of operation with different gas compositions and operational conditions like temperature and relative humidity.

Developments of oil-free Bakelite resistive plate chambers for particle physics experiments

In this paper, we sumarized a Bakelite Resistive Plate Chamber (RPC) with non-oil surface treatment. This type of RPC has been installed and run smoothly in BESIII Muon identification system and Daya Bay cosmic Muon veto system. Based on its good performances, it has been futher studied as the sensitive detector of a digital hadron calorimeter for measuring the energies of particles in a hadron jet and as a thermal neutron detector. In addition, since the bulk resistivity of Bakelite plates can be controlled, futher developments with low bulk resistivity are being undertaken to guarantee high rate capability in experiments.

Thermally induced microstructural changes and its influence on electrical conductivity of a polymer‐based bakelite RPC detector material: A positron lifetime study

Annealing studies have been carried out to understand the temperature induced microstructural changes in Bakelite (P‐120 NEMA LI‐1989 Grade XXX) Resistive Plate Chamber (RPC) detector material using Positron annihilation lifetime spectroscopy (PALS), Fourier transform infrared spectroscopy (FTIR), and XRD. The variation of positron lifetime parameters viz., ortho‐Positronium lifetime (τ3) and free volume size (Vf) increases marginally above glass transition temperature Tg as a result of structural changes due to segmental mobility. The drastic increase of free volume parameters above 240°C attributed to the reduction in strength of C—H bond of the aliphatic bridges and cleavage of methylene bridges of the polymer network, which is supported by the FTIR results. The XRD results show the reduction in crystallinity and average crystallite size of Bakelite on annealing correlates well with the free volume and electrical conductivity. The temperature induced electrical conductivity and activation energy is also correlated with the positron lifetime parameters. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 793‐800, 2013

High rate resistive plate chamber for LHC detector upgrades

The limitation of the detection rate of standard bakelite resistive plate chambers (RPCs) used as muon detectors in the LHC experiments has prevented the use of such detectors in the high rate regions in both CMS and ATLAS detectors. One alternative to these detectors is RPCs made with low resistivity glass plates (1010Ωcm), a beam test at DESY has shown that such detectors can operate at few thousand Hz/cm2 with high efficiency (>90%).

Measurement of electrical properties of electrode materials for the bakelite Resistive Plate Chambers

Single gap (gas gap = 2 mm) bakelite Resistive Plate Chamber (RPC) modules of various sizes from 10 cm × 10 cm to 1 m × 1 m have been fabricated, characterized and optimized for efficiency and time resolution. Thin layers of different grades of silicone compound are applied to the inner electrode surfaces to make them smooth and also to reduce the surface resistivity. In the silicone coated RPCs an efficiency ∼ 96% and time resolution ∼ 2 ns (FWHM) have been obtained for both the streamer and the avalanche modes of operation. Before fabrication of detectors the electrical properties such as bulk resistivity and surface resistivity of the electrode materials are measured carefully. Effectiveness of different silicone coating in modifying the surface resistivity was evaluated by an instrument developed for monitoring the I-V curve of a high resistive surface. The results indicate definite correlation of the detector efficiency for the atmospheric muons and the RPC noise rates with the surface resistivity and its variation with the applied bias voltage. It was also found that the surface resistivity varies for different grades of silicone material applied as coating, and the results are found to be consistent with the detector efficiency and noise rate measurements done with these RPCs.

Results from the PHENIX RPC R&D and long-term performance monitoring

A new Resistive Plate Chamber (RPC) based fast muon trigger system has been developed and partially installed in the PHENIX experiment. This new trigger will allow the PHENIX data acquisition system to efficiently sample high pT (>20GeV/c) muons from W decays in polarized proton+proton collisions at s=500GeV at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. This measurement will significantly improve our knowledge of flavor separated quark and anti-quark polarization in the proton. Since 2005, a multi-institutional effort within the PHENIX Forward Trigger group was devoted to study the properties and performance of bakelite RPCs. In this presentation, the results of the PHENIX RPC R&D will be reported.

Simulation estimation of RB1 station's sensitivities and hit rates for e+/e− particles by RPCs

Resistive plate chambers (RPCs) have been chosen as a part of the muon trigger detector, in both the endcap and barrel regions of a compact muon solenoid (CMS) experiment, which will work in extreme radiation backgrounds. In order to evaluate the response of the RPC detector in the CMS background environment, the RB1 barrel region has been investigated. The present simulation for e+/e− using GEANT3.21 code predicts hit rates of 0.048 (0.045) and 0.040 (0.038) Hz cm−2 using a bakelite and glass-based RPC setup. A similar trend in the results of GEANT4 Monte Carlo code with the same RPC configurations is also reported.

Study of timing properties of single gap high-resistive bakelite RPC

The time resolution for several single gap (2 mm) prototype Resistive Plate Chambers (RPC) made of high resistive ( ρ ~ 10 10 – 10 12 Ω cm ), 2 mm thick matt finished bakelite paper laminates with silicone coating on the inner surfaces, has been measured. The time resolution for all the modules has been found to be ~ 2 ns at the plateau region.