Here we report on a particular type of RPC that presents up to 99% efficiency for minimum ionizing particles and a very sharp time resolution, below 50 ps sigma in the most optimized conditions. Our 9 cm2 cells, made with glass and metal electrodes that form accurately spaced gaps of a few hundred micrometers, are operated at atmospheric pressure in non-flammable gases and can be economically produced in large quantities, opening perspectives for the construction of large area time of flight systems.
We constructed a new time-of-flight (TOF) detector consisting of resistive plate chambers (RPCs) to measure particle energy in the BGOegg experiment. The BGOegg-RPC has a unique feature which enables us to cover a large area with a small number of readout channels. For this purpose, we developed the RPC with a strip size of 2.5 cm $\times$ 100 cm. The BGOegg-RPC covers an area of 320 cm $\times$ 200 cm with only 256 channels of readout electronics. In case of large readout RPCs, an originated signal is distorted and dispersed during propagation. In addition, there happens a signal reflection a…
Usage of electrodes made of glass with low bulk resistivity seems to be a promising way to adapt the Resistive Plate Chambers (RPC) to the high-rate environment of the upcoming CBM experiment. A pilot four-gap RPC sample with electrodes made of phosphate glass, which has bulk resistivity in the order of 10^10 Ohm cm, has been studied with MIP beam for TOF applications. The tests have yielded satisfactory results: the efficiency remains above 95% and the time resolution stays within 120 ps up to the particle rate of 18 kHz/cm2. The increase in rate from 2.25 to 18 kHz/cm2 leads to an increase o…
In this work we describe some recent results concerning the application of Resistive Plate Chambers operated in avalanche mode at atmospheric pressure for high-resolution time-of-flight measurements. A combination of multiple, mechanically accurate, thin gas gaps and state-of-the-art electronics yielded an overall (detector plus electronics) timing accuracy better than 50 ps sigma with a detection efficiency up to 99% for MIPs. Single gap chambers were also tested in order to clarify experimentally several aspects of the mode of operation of these detectors. These results open perspectives of …
We have developed multi-gap resistive plate chambers (MRPCs) with 2.5 x 200 cm2 readout strips for the time-of-flight (TOF) detector system of the LEPS2 experiment at SPring-8. These chambers consist of 2 stacks and 5 gas gaps per stack, in a mirrored configuration. A time resolution of sigma ~ 80 ps was achieved for any position within a strip (at above 99% detection efficiency); after performing the time-charge slewing correction, this value could be reduced to 60 ps. A link between the small contribution of the slewing correction to timing and the suppression of modal dispersion in the dete…
Nowadays, commonly used Resistive Plate Chambers (RPCs) have counting rate capabilities of ~10E4Hz/cm2 and position resolutions of ~1cm. We have developed small prototypes of RPCs (5x5 and 10x10cm2) having rate capabilities of up to 10E7Hz/cm2 and position resolutions of 50 micron("on line" without application of any treatment method like "center of gravity"). The breakthrough in achieving extraordinary rate and position resolutions was only possible after solving several serious problems: RPC cleaning and assembling technology, aging, spurious pulses and afterpulses, discharges in the amplifi…
A large area Resistive Plate Chamber (RPC) with a total active surface of 160x10 cm2 was built and tested. The surface was segmented in two 5 cm wide strips readout on both ends with custom, very high frequency, front end electronics. A timing resolution between 50 and 75 ps sigma with an efficiency for Minimum Ionizing Particles (MIPs) larger than 95% was attained over the whole active area, in addition with a position resolution along the strips of 1.2 cm. Despite the large active area per electronic channel, the observed timing resolution is remarkably close to the one previously obtained (…
The results of an experimental feasibility study of a position sensitive thermal neutron detector based on a resistive plate chamber (RPC) are presented. The detector prototype features a thin-gap (0.35 mm) hybrid RPC with an aluminium cathode lined with a 2 $μ$m thick $^{10}B{_4}C$ neutron converter layer enriched in $^{10}B$ and a float glass anode. A detection efficiency of ${\approx}$ 6.2 ${\%}$ was measured for the neutron beam ($λ$ =2.5 $Å$) at normal incidence. A spatial resolution better than 0.5 mm FWHM was demonstrated.
Resistive Plate Chamber (RPC) is a gaseous detector, known for its good spatial resolution and excellent time resolution. Due to its fast response and excellent time resolution, it is used for both triggering and timing purpose. But the time resolution of RPC is dependent on the detector geometry, applied voltage and the gas mixture used for detector operation. In this work, we have tried to develop a numerical model to estimate the time resolution of the detector. The model is developed using COMSOL Multiphysics, a commercially available finite element method solver. Using the primary ionizat…
The Resistive Plate Chambers (RPC) are low-cost charged-particle detectors with good timing resolution and potentially good spatial resolution. Using RPC as gamma detector provides an opportunity for application in positron emission tomography (PET). In this work, we use GEANT4 simulation package to study various methods improving the detection efficiency of a realistic RPC-based PET model for 511keV photons, by adding more detection units, changing the thickness of each layer, choosing different converters and using multi-gaps RPC (MRPC) technique. Proper balance among these factors are discu…
Multi-gap RPC prototypes with readout on a multi-strip electrode were developed for the small polar angle region of the CBM-TOF subdetector, the most demanding zone in terms of granularity and counting rate. The prototypes are based on low resistivity ($\sim$10$^{10}$ $Ω$cm) glass electrodes for performing in high counting rate environment. The strip width/pitch size was chosen such to fulfill the impedance matching with the front-end electronics and the granularity requirements of the innermost zone of the CBM-TOF wall. The in-beam tests using secondary particles produced in heavy ion collisi…
The time resolution of Multigap Resistive Plate Counters (MRPCs) to $511$ keV gamma rays has been investigated using a $^{22}$Na source and four detectors. The MRPCs time resolution has been derived from the Time-of-Flight information, measured from pairs of space correlated triggered events. A GEANT4 simulation has been performed to analyze possible setup contributions and to support experimental results. A time resolution (FWHM) of $376$ ps and $312$ ps has been measured for a single MRPC with four $250$ $μ$m gas gaps by considering respectively one and two independent pairs of detectors.
The 50~kton Iron Calorimeter (ICAL) detector at the underground India based Neutrino Observatory (INO) will make measurements on atmospheric neutrinos. Muons produced in charged current (CC) interactions of muon neutrinos with the iron are tracked spatially and temporally through the signals that they produce in the Resistive Plate Chambers~(RPCs) that are interleaved with iron layers. Since the RPCs will be operated in the avalanche mode the signal rise-time is $\sim~1~\rm{nsec}$ resulting in a fast time response. While the muon track is derived from the X and Y hit information of the RPCs an…
Resistive plate chambers (RPC) lined with $^{10}B_{4}$C neutron converters is a promising cost effective technology for position-sensitive thermal neutron detection capable to outperform $^{3}$He-based detectors in terms of spatial resolution and timing. However, as for the other types of gaseous detectors with a single layer of $^{10}B_{4}$C at normal beam incidence, the detection efficiency to thermal neutrons of a single-gap $^{10}B$-RPC is only about 6%. Aiming to overcome this limitation, we introduce a multi-layer $^{10}B$-RPCs detector with a stack of ten double-gap hybrid RPCs. A descr…
Multilayer position-sensitive 10B-RPC thermal neutron detectors offer an attractive combination of sub-millimeter spatial resolution and high (>50%) detection efficiency. Here we describe a new position reconstruction method based on a statistical approach. Using experimental data, we compare the performance of this method with that of the centroid reconstruction. Both methods result in a similar image linearity/uniformity and spatial resolution. However, the statistical method allows to improve the image quality at the detector periphery, offers more flexible event filtering and allows to dev…
The time resolution for several single gap (2 mm) prototype Resistive Plate Chambers (RPC) made of high resistive (bulk resistivity ~ 10^10 - 10^12 ohm 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.
The Resistive Plate Chamber (RPC) is widely used in experiments of high energy physics as trigger detector as its good time resolution and high efficiency. In the traditional layout of RPC, the graphite layers are indispensable parts. The working voltage is applied on these layers and the charge of avalanche dissipates through them. In this paper, a new design which removes the graphate layers is proposed to improve the structure of this detector. With this new design, the negative effect from the ununiformity of graphite is eliminated and the structure of detector is simplified.
The Muon Upgrade Phase II of the Compact Muon Solenoid (CMS) aims to guarantee the optimal conditions of the present system and extend the $η$ coverage to ensure a reliable system for the High Luminosity Large Hadron Collider (HL-LHC) period. The Resistive Plate Chambers (RPCs) system will upgrade the off-detector electronics (called link system) of the chambers currently installed chambers and place improved RPCs (iRPCs) to cover the high pseudo$-$rapidity region, a challenging region for muon reconstruction in terms of background and momentum resolution. In order to find the best option for …
During Phase-2 of the LHC, known as the High Luminosity LHC (HL-LHC), the accelerator will increase its instantaneous luminosity to 5 $\times$ 10$^{34}$ cm$^{-2}$ s$^{-1}$, delivering an integrated luminosity of 3000 fb$^{-1}$ over 10 years of operation starting from 2027. In view of the HL-LHC, the CMS muon system will be upgraded to sustain efficient muon triggering and reconstruction performance. Resistive Plate Chambers (RPCs) serve as dedicated detectors for muon triggering due to their excellent timing resolution, and will extend $|η|$ (pseudorapidity) up to a region of 2.4. Before Long …
We present results of simulations on the influence of photon propagation and the Cherenkov effect on the time resolution of LSO:Ce scintillators. The influence of the scintillator length on the coincidence time resolution is shown. Furthermore, the impact of the depth of interaction on the time resolution, the light output and the arrival time distribution at the photon detector is simulated and it is shown how these information can be used for time walk correction.
Resistive Plate Chamber (RPC) is a type of gaseous detector having excellent time and position resolutions. VECC is involved in the R\&D of indigenously developed bakelite RPCs. The largest size of bakelite RPC developed in India is 100 cm $\times$ 100 cm. We present here the test results of a bakelite sample along with the cosmic ray test results of a bakelite RPC (30 cm $\times$ 30 cm $\times$ 0.2cm) fabricated at VECC. The steps taken towards the development of a large size (240 cm $\times$ 120 cm $\times$ 0.2 cm) bakelite RPC have also been discussed.
The innermost station of the present ATLAS forward muon detector needs to be upgraded for the super-LHC. We present a proposal to replace it with a sandwiched detector composed of several layers of small-radius Monitored Drift Tube chambers (sMDT) for precision tracking measurement and two stations of multi-gap Resistive Plate Chambers (mRPC) for triggering purpose. We describe the layout of the upgraded detector and the trigger strategy. Several modifications to the RPCs used in the ATLAS barrel region are needed to satisfy the super-LHC requirements. Various studies with the proposed mRPC ti…
With the newly gained interest in the time of flight method for positron emission tomography (TOF-PET), many options for pushing the time resolution to its borders have been investigated. As one of these options the exploitation of the Cherenkov effect has been proposed, since it allows to bypass the scintillation process and therefore provides almost instantaneous response to incident 511keV annihilation photons. Our simulation studies on the yield of Cherenkov photons, their arrival rate at the photon detector and their angular distribution reveal a significant influence by Cherenkov photons…
A detailed numerical simulation has been performed to investigate the timing properties of a standard RPC geometry in order to optimize its application in INO-ICAL experiment designed for studying atmospheric neutrinos. The timing information provided by the RPC is an important observable in the experiment to determine the direction of the neutrinos. Effects of various operating conditions and design components on the RPC timing response, mainly the average signal arrival time and the time resolution have been studied in this context. The dependence of the detector efficiency on the same param…
The India-based Neutrino Observatory (INO) is a project aimed at building a large underground laboratory to explore the Earth's mater effects on the atmospheric neutrinos in multi-GeV range. 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 $\times$ 2 m size will be operated in the avalanche mode. A small variation in the compositions of ionizing gaseous medium in the RPC affects its performance. Study of the charge distribution of the RPC at different gas compositi…
Performances of several single gap (gas gap 2 mm) prototype Resistive Plate Chambers (RPC) made of high resistive (ρ \sim 1010 - 1012 Ω cm) bakelite, commercially available in India have been studied in recent times. To make the inner electrode surfaces smooth, a thin coating of silicone has been applied. An efficiency > 90% and time resolution \sim 2 ns (FWHM) have been obtained for both the streamer and the avalanche mode. The induced charge distributions of those silicone coated RPC are studied and the results are presented. A numerical study on the effect of surface roughness of the resist…
Positron Emission Tomography (PET) using time-of-flight information, which can greatly improve the quality of the reconstructed image, has recently become an exciting topic. In this work, 3.2mm*3.2mm*25mm finger-like LYSO crystals were used to make a 5*5 array, coupled to the Hamamatsu H8500 photomultiplier tube (PMT) as a detector. A fast leading-edge discriminator was designed for the LYSO-H8500 detector. Average coincidence time resolution FWHM of 330 ps was obtained for the LYSO detector with a reference BaF2 detector, whose time resolution for 511 keV γ-rays was FWHM 150 ps. Time resoluti…
An analytical method is presented with allows to estimate the energy resolution of time-of-flight neutron spectrometers, as well as its partial contributions, over a dynamical range that extends from the elastic line to the accessible inelastic regions. Such a method, already successfully applied in the past to the TOSCA and HET neutron inelastic scattering spectrometers installed at the ISIS neutron spallation source [A M Gaspar, PhD Thesis, Universidade Tecnica de Lisboa, 2004], is here applied to the high resolution time-of-flight spectrometer TOFTOF, mainly dedicated to quasi-elastic neutr…
We present here detailed derivations of mathematical expressions for the accuracy in the arrival direction of particles estimated using a set of stacked resistive plate chambers (RPCs). The expressions are validated against experimental results using data collected from the prototype detectors (without magnet) of the upcoming India-based Neutrino Observatory (INO). We also present a theoretical estimate of angular resolution of such a setup. In principle, these expressions can be used for any other detector with an architecture similar to that of RPCs.
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 en…
Time of flight system (TOF) based on MRPC technology is widely used in modern physics experiments, and it also plays an important role in particle identification. With the increase of accelerator energy and luminosity, TOF system is required to indentify definite particles precisely under high rate environment. The MRPC technology TOF system can be defined as three generations. The first generation TOF is based on float glass MRPC and its time resolution is around 80ps, but the rate is relatively low (typically lower than 100Hz/cm2). The typical systems are TOF of RHIC-STAR, LHC-ALICE and BES …
Aim: Investigate whether a time walk assessment derived from crystal light sharing and multi-photon time stamps can improved the TOF resolution. Method: Monte Carlo simulations were performed for SiPM (FBK-NUV-HD) coupled to conventional 4x4 mm2 pixelated LSO (0.2%Ca:Ce ) and also coupled to 8x4 mm2 pixelated LSO in which a triangular optical window allows light sharing between the two 4x4 mm2 sub-pixels depending on the DOI. A time walk estimation was modelled as a DOI dependent weighted sum of the time differences within the photons detection sequence. The DOI dependent weights were optimize…
Aiming to measure the difference in arrival times of two coincident gamma-photons with an accuracy in the order of 200 ps, time-of-flight positron emission tomography systems commonly employ silicon photomultipliers (SiPMs) and high-resolution digitization electronics, application specific integrated circuits (ASICs). This work evaluates the performance of the TOFPET2 ASIC, released by PETsys Electronics S.A. in 2017, dependent on its configuration parameters in multi-channel coincidence measurements. SiPM arrays fabricated by different vendors (KETEK, SensL, Hamamatsu, Broadcom) were tested i…
The SDHCAL technological prototype is a $1 \times 1 \times 1.3$ m$^3$ high-granularity Semi-Digital Hadronic CALorimeter using Glass Resistive Plate Chambers as sensitive medium. It is one of the two HCAL options considered by the ILD Collaboration to be proposed for the detector of the future International Linear Collider project. The prototype is made of up to 50 GRPC detectors of 1 m$^2$ size and 3 mm thickness each with an embedded semi-digital electronics readout that is autotriggering and power-pulsed. The GRPC readout is finely segmented into pads of 1 cm$^2$. Measured performances of t…
The aim of this work is to show the potential capabilities of monolithic crystals coupled to large SiPM arrays, to be considered as detector blocks for PET scanners enabling Time Of Flight (TOF) capabilities. Monolithic blocks allow one to decode the 3D photon impact position. This approach, along with TOF information, can be of high interest in clinical Positron emission tomography (PET) applications where a typical ring configuration is used. In this manuscript, we evaluate an ASIC- based readout for digitizing all signals coming from analog photosensors. Validation results with one-to-one c…
Nowadays, in Positron Emission Tomography (PET) systems, a Time of Flight information is used to improve the image reconstruction process. In Time of Flight PET (TOF-PET), fast detectors are able to measure the difference in the arrival time of the two gamma rays, with the precision enabling to shorten significantly a range along the line-of-response (LOR) where the annihilation occurred. In the new concept, called J-PET scanner, gamma rays are detected in plastic scintillators. In a single strip of J-PET system, time values are obtained by probing signals in the amplitude domain. Owing to Com…
For precise start time determination a Beam Fragmentation T$_0$ Counter (BFTC) is under development for the Time-of-Flight Wall of the Compressed Baryonic Matter Spectrometer (CBM) at the Facility for Antiproton and Ion Research (FAIR) at Darmstadt/Germany. This detector will be located around the beam pipe, covering the front area of the Projectile Spectator Detector. The fluxes at this region are expected to exceed 10$^5$cm$^{-2}$s$^{-1}$. Resistive plate chambers (RPC) with ceramic composite electrodes could be use because of their high rate capabilities and radiation hardness of material. …
At a spallation neutron source, the wavelength of a neutron is generally determined by its time-of-flight (TOF) from the source to the detector. The achievable precision is ultimately limited by the non-zero emission time-width of the source/moderator system. Particularly, coupled moderators that are used to produce high intensity cold neutron beams show long "tails" in the intensity/time distribution for all wavelengths. For this reason much less intense decoupled moderators are often used for instruments that require high resolution. We present here a novel technique for dynamic energy filte…
We report on studies of fast triggering and high-precision tracking using Resistive Plate Chambers (RPCs). Two beam tests were carried out with the 180 GeV muon beam at CERN using RPCs with gas gaps of 1.00 or 1.15 mm and equipped with readout strips with 1.27 mm pitch. This is the first beam test of RPCs with fine-pitch readout strips that explores simultaneously precision tracking and triggering capabilities. RPC signals were acquired with precision timing and charge integrating readout electronics at both ends of the strips. The time resolution was measured to be better than 600 ps and the …
While in a triggered experiment the matching of the RPC transmission line impedance with the one of the front-end electronics is less critical, for a trigger-less data recording this becomes mandatory. As expected, impedance matching is not straightforward when other requirements in terms of time and position resolutions, efficiency and granularity, have to be fulfilled in the same time. A method and the very first results obtained with a RPC prototype built based on it, presented in this paper, show that the impedance matching, independent of its granularity, can be achieved using an innovati…
The high pseudorapidity ($η$) region of the Compact Muon Solenoid (CMS) muon system is covered by Cathode Strip Chambers only and lacks redundant coverage despite the fact that it is a challenging region for muons in terms of backgrounds and momentum resolution. During the annual Year-End Technical Stops 2022 & 2023, two new layers of improved Resistive Plate Chambers (iRPC) will be added, RE3/1 & RE4/1, which will completely cover the region of $1.8 < |η| < 2.4$ in the endcap. Thus, the additional new chambers will lead to increase efficiency for both trigger and offline reconstruction in the…
Plasma profiling time of flight mass spectrometry (PP-TOFMS) has recently gained interest, as it enables the elemental profiling of semiconductor structures with high depth resolution in short acquisition times. As recently shown by Tempez et al., PP-TOFMS can be used to obtain the composition in the structures for modern field effect transistors [1]. There, the results were compared to conventional SIMS measurements. In the present study, we compare PP-TOFMS measurements of an Al-/In-/GaN quantum well multi stack to established micro- and nano-analysis techniques like cathodoluminescence (CL)…
We describe the most recent efforts made by various groups in implementing resistive electrodes in micropattern gaseous detectors with the aim to combine in the same design the best features of RPCs (for the example, their robustness and spark protection property) with the high granularity and thus the good position resolution offered by microelectronic technology. In the stream of this activity, we have recently developed two novel detectors with resistive electrodes: one was based on resistive micromeshes and the second one is a MSGC with resistive electrodes. We have demonstrated that the r…
In these proceedings we report on the status of the ALICE Time-Of-Flight (TOF) detector. The running performance of the Run 1 (2009-2013) and Run 2 (2015-present) data taking campaigns are compared. The Particle IDentification (PID) capabilities of the detector are presented and discussed in the light of the improved detector calibration that allowed to reach a timing resolution of 56 ps.
The ALICE Time-Of-Flight (TOF) detector at LHC is based on the Multigap Resistive Plate Chambers (MRPCs). The TOF performance during LHC Run 2 is here reported. Particular attention is given to the improved time resolution reached by TOF detector of $56$ ps, with the consequently improved particle identification capabilities.
Since its inception, velocity map imaging (VMI) has been a powerful tool for measuring the 2D momentum distribution of photoelectrons generated by strong laser fields. There has been continued interest in expanding it into 3D measurements either through reconstructive or direct methods. Recently much work has been devoted to the latter of these, particularly by relating the electron time-of-flight (TOF) to the third momentum component. The technical challenge here is having timing resolution sufficient to resolve structure in the narrow (< 10 ns) electron TOF spread. Here we build upon work in…
Single gap (gas gap 2 mm) bakelite Resistive Plate Chamber (RPC) modules of various sizes from 10 cm \times 10 cm to 1 m \times 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 > 90% and time resolution \sim 2 ns (FWHM) have been obtained for both the streamer and the avalanche mode of operation. Before fabrication of detectors the electrical properties …
The ATLAS experiment at the Large Hadron Collider (LHC) employs a trigger system consisting of a first-level hardware trigger (L1) and a software-based high-level trigger. The L1 muon trigger system selects muon candidates, assigns them to the correct LHC bunch crossing and classifies them into one of six transverse-momentum threshold classes. The L1 muon trigger system uses resistive-plate chambers (RPCs) to generate the muon-induced trigger signals in the central (barrel) region of the ATLAS detector. The ATLAS RPCs are arranged in six concentric layers and operate in a toroidal magnetic fie…
We have developed a novel detector, referred to as an "$α$-ToF detector", for correlated measurements of atomic masses and decay properties of low-yield, short-lived radioactive isotopes using a multi-reflection time-of-flight mass spectrograph. By correlating measured time-of-flight signals with decay events, it will be possible to suppress background events and obtain accurate, high-precision mass values even in cases of very low event rates. An offline test of the $α$-ToF detector has shown that the time-of-flight detection efficiency for 5.48~MeV $α$-rays is more than 90\% and yields a tim…
