Quartz Radiator Research Articles

Timing resolution of a LAPPD prototype measured with CERN PS test beams

The Electron-Ion Collider (EIC) facility is envisaged for the ultimate exploration of the nucleons, the nuclear matter and the strong force, thanks to its wide range of centre-of-mass energy, its large luminosity, and the polarization of its beams. The ePIC detector, designed to cope with the EIC physics potential, involves several Cherenkov radiation-based sub-systems for Particle Identification. They need reliable and effective Single Photo-Electron (SPE) sensors. We report about the timing performance of a LAPPD prototype tested with Cherenkov light produced in a quartz radiator at a CERN PS hadron test beam. Results show a SPE time resolution of 87 ps rms.

Geant4 simulations of monochromatic Cherenkov radiation in thin quartz targets for different experimental conditions

In light of our recent research, we discussed the possibility of observing quasimonochromatic Cherenkov Radiation (ChR) spectral lines from a dispersive medium (thin quartz radiator). Such experimental results were verified on the Mainz Microtron MAMI, Germany [1], while both the polarization currents analytical model [2] and Geant4 [3] simulations were used to analyze the results. To describe the Cherenkov radiation process, the Geant4 toolkit uses only the approximation obtainable for an infinitely thick emitter (cos θ = 1 / βn(λ), where θ is Cherenkov’s angle of emission, β is reduced velocity, and n(λ) is a refractive index as a function of emitted radiation’s wavelength λ) and doesn’t consider its actual dimensions. Tamm’s theory [4] predicts some broadening of the ChR angular distribution with a radiator thinning. Consequently, Geant4 gave inadequate results for the pencil-like electron beams compared to the polarization currents model and the experiment. However, unlike in the analytical calculations, we needed to consider more realistic Gaussian electron beams to obtain better results with Geant4. Therefore, obtained results primarily manifest beam characteristics rather than the ChR itself, i.e., its intrinsic characteristics are masked. Now, the idea is to present additional simulation results with further variations of the quartz’s thickness (in preparation for future experiments), confirming the last conclusion without any doubt.

Radiator thickness and its effects on Cherenkov spectral lines

In this work, we applied the polarization currents method to describe the Cherenkov radiation spectral lines measured using a thin quartz radiator with frequency dispersion. We also considered the real characteristics of the used electron beam to reproduce experimental results. The procedure is based on numerical calculations in C++, while for comparing purposes, we also used the data previously simulated with the Geant4 toolkit. From such a comparison, we conclude that the developed method better agrees with the experimental data. Besides that, as Cherenkov interference effects play an essential role in thin radiators, we use our method to predict the monochromaticity of Cherenkov spectral lines for both thinner and thicker radiators compared to the experimental one.

TORCH pattern recognition and particle identification performance

The TORCH detector aims to provide K/π (K/p) separation up to a momentum of about 10 (15) ▪ by measuring their time-of-flight at the LHCb detector. Prompt Cherenkov photons are produced in a quartz radiator bar of 10 mm thickness, and propagated via total internal reflection to the periphery of the detector, where they are focused onto an array of microchannel plate photomultipliers that measure the photon arrival time and position. Pattern recognition techniques are used to compare the likelihood that the detector image is due to a given particle hypothesis. Good performance is obtained even for very high detector occupancies.

Study of hybrid micropattern gaseous detector with CsI photocathode for Super Tau-Charm facility RICH

Super τ-Charm facility (STCF) is a future electron-positron collider operating in the τ-Charm energy region with the aim of studying hadron structure and spectroscopy. The baseline design of the STCF barrel particle identification (PID) detector, which covers momentum up to 2 GeV/c, is provided by a Ring Imaging Cherenkov Counter (RICH). The RICH features an approximately focusing design with liquid perfluorohexane sealed in a quartz container as the radiator and a hybrid combination of CsI-coated THGEMs and Micromegas as the photo-electron detector. A 16×16 cm2 prototype with a quartz radiator has been built and tested at DESY and stably operated with an effective gain of 105. In this paper, the design, performance, and reconstruction algorithm of RICH detectors are discussed.

New developments from the TORCH R&D project

TORCH is a large-area and high-precision time-of-flight detector, designed to provide charged particle identification over a 2–20GeV/c momentum range. The TORCH detector comprises a 10 mm thick quartz radiator, instrumented with photon detectors, which precisely time and measure the arrival positions of the Cherenkov photons. The photon detectors are micro-channel plate photo-multiplier tubes (MCP-PMTs) comprising a finely segmented anode of 64 × 64 anode pads, electronically ganged into 64 × 8 pixels, over a 53 × 53mm2 area, an excellent intrinsic time resolution of ∼ 30ps, and a long lifetime of up to ≳ 5C/cm2. The current version of the MCP-PMTs used by TORCH have been developed with an industrial partner, Photek Ltd, to satisfy the stringent requirements of the detector. The TORCH R&D programme has successfully demonstrated the detector concept through extensive laboratory and beam tests. A TORCH prototype has been constructed and has yielded encouraging results when exposed to low momentum charged hadrons. Characteristic patterns of Cherenkov photons have been recorded, illustrating the required spatial accuracy and timing resolution of 70 ps per photon. Both laboratory and beam test results are approaching the design goals of the TORCH detector.

Picosecond timing of charged particles using the TORCH detector

TORCH is a large-area, high-precision time-of-flight (ToF) detector designed to provide charged-particle identification in the 2–20 GeV/c momentum range. Prompt Cherenkov photons emitted by charged hadrons as they traverse a 10 mm quartz radiator are propagated to the periphery of the detector, where they are focused onto an array of micro-channel plate photomultiplier tubes (MCP-PMTs). The position and arrival times of the photons are used to infer the particles’ time of entry in the radiator, to identify hadrons based on their ToF. The MCP-PMTs were developed with an industrial partner to satisfy the stringent requirements of the TORCH detector. The requirements include a finely segmented anode, excellent time resolution, and a long lifetime. Over an approximately 10 m flight distance, the difference in ToF between a kaon and a pion with 10 GeV/c momentum is 35 ps, leading to a 10–15 ps per track timing resolution requirement. On average 30 photons per hadron are detected, which translates to a single-photon time resolution of 70 ps. The TORCH R&D program aims to demonstrate the validity of the detector concept through laboratory and beam tests, results from which are presented. A timing resolution of 70–100 ps was reached in beam tests, approaching the TORCH design goal. Laboratory timing tests consist of operating the MCP-PMTs coupled to the TORCH readout electronics. A time resolution of 50 ps was measured, meeting the TORCH target timing resolution.

DEVELOPMENT AND RESEARCH OF A HIGH-PERFORMANCE ELECTRONIC DEVICE FOR OZONE SYNTHESIS IN A VIBRATION DRYER

The article analyzes the features of drying grain raw materials using a vibrating dryer, in which the drying agent is a mixture of heated air in combination with ozone of a certain concentration. Based on the analysis to intensify this process, we propose to develop a high-performance electronic device for ozone synthesis. The scientific study considers oscillations that increase and update the heat transfer surface regardless of the method of supply of the drying agent. Due to this, the removal of moisture intensifies, the drying speed increases. Having conducted a search and analyzed the process of vibration drying, we can say that in the future will progress two main trends in their development. This is the use of vibration in combination with the action of ozone on the raw material entering the drying. Ozone interacts with the membrane structure of bacteria, fungi, the structural unit of viruses, which leads to a violation of its barrier function and their death. The bactericidal effect of ozonation is superior to the effect of ultraviolet quartz radiation. Bactericidal effect from quartz irradiation for 60 minutes identical to the bactericidal effect of ozone for 3 minutes Ozone has a high penetrating ability and also shows antibacterial activity against gram-positive flora, Escherichia coli, epidermal staphylococcus. This method is the most effective general method of controlling the dynamic state of the processed raw materials. The analysis allows us to suggest possible solutions for the use of low-frequency oscillations for separation processes and outline the prospects for their application. It is proved that the existing equipment is used with significant energy consumption and high cost. The constructions and technologies considered in the work do not completely exhaust the possibilities of using vibration and ozone, although they testify to the expediency of their application and combination not only in agricultural production, but also in other industries in order to intensify processes and obtain quality products.

Front-end electronic readout system for the Belle II imaging Time-Of-Propagation detector

The Time-Of-Propagation detector is a Cherenkov particle identification detector based on quartz radiator bars for the Belle II experiment at the SuperKEKB electron-positron collider. The purpose of the detector is to identify the type of charged hadrons produced in electron-positron collisions, and requires a single photon timing resolution below 100 picoseconds. A novel front-end electronic system was designed, built, and integrated to acquire data from the 8192 microchannel plate photomultiplier tube channels in the detector. Waveform sampling of these analog signals is done by switched-capacitor array application-specific integrated circuits. The processes of triggering, digitization of windows of interest, readout, and data transfer to the Belle II data acquisition system are managed by Xilinx Zynq-7000 programmable system on a chip devices.

Particle identification in the Belle II experiment

The Belle II experiment integrates two dedicated particle identification (PID) subdetectors for pion/kaon separation. The Aerogel Ring Image Cherenkov (ARICH) detector is a forward region PID detector based on two layers of aerogel read out by hybrid avalanche photo detectors. The Time of Propagation (TOP) detector is a novel Cherenkov barrel PID system built for the Belle II detector upgrade based on quartz radiator bars read out by Micro-Channel Plate PMTs. The readout electronics of the TOP system are built around a switched capacitor array waveform sampling ASIC operating at 2.7 GSa/s. Acquired waveforms are processed in real time in the front-end electronics, extracting the individual timing of detected photons to better than 100 ps. This contribution presents the concept of the Belle II particle identification systems with a focus on the current status of commissioning, calibration and operation of the Belle II TOP detector.

Compensating H+ and Li+ ions in quartz structural channels of the gold fields of Darasun ore field (Eastern Transbaikal, Russia): electron paramagnetic resonance data

The composition and diffusion mobility of the compensating ions in the quartz structural channels of the gold fields in the Darasun, Teremkinskoye, and Talatuy gold fields of the Darasun ore field were examined using the electron paramagnetic resonance method. The assessment of the properties and peculiarities of the ion distribution in quartz was based on their ability to participate in the neutralization of the electric charges of the structural defects occurring in the minerals. In this regard, the ion composition was evaluated by the ratio of the concentrations of the Ti-centers using various compensators. Their mobility was determined by the center formation rate during the quartz radiation exposure. The research demonstrated the availability of two major compensating ions, H+ and Li+, in the quartz structural channels of the gold fields in the Darasun ore field. The diffusion mobility of the H+ ions in the channels was observed to be 1–2 orders of magnitude higher than that of Li+. The correlation link between the compensating ions in the mineral and fluid compositions was not obtained based on the data analysis. A difference was identified between the ratio of the H+ and Li+ concentrations in the quartz structural channels of different fields. Further, the highest concentration of H+ ions and the lowest concentration of Li+ ions were recorded for the quartz in the Darasun field; the inverse correlation was observed for the quartz in the Talatuy field, which can be attributed to the mixing of the fluid gas component during the ore formation process. The electron paramagnetic resonance method can be used for the quantitative assessment of the degree of quartz dynamic recrystallization.

Testbeam studies of a TORCH prototype detector

TORCH is a novel time-of-flight detector that has been developed to provide charged-particle identification between 2 and 10 GeV/c momentum. TORCH combines arrival times from multiple Cherenkov photons produced within a 10 mm-thick quartz radiator plate, to achieve a 15 ps time-of-flight resolution per incident particle. A customised Micro-Channel Plate photomultiplier tube (MCP-PMT) and associated readout system utilises an innovative charge-sharing technique between adjacent pixels to obtain the necessary 70 ps time resolution of each Cherenkov photon. A five-year R&D programme has been undertaken, culminating in the construction of a small-scale prototype TORCH module. In testbeams at CERN, this prototype operated successfully with customised electronics and readout system. A full analysis chain has been developed to reconstruct the data and to calibrate the detector. Results are compared to those using a commercial Planacon MCP-PMT, and single photon resolutions approaching 80 ps have been achieved. The photon counting efficiency was found to be in reasonable agreement with a GEANT4 Monte Carlo simulation of the detector. The small-scale demonstrator is a precursor to a full-scale TORCH module (with a radiator plate of 660×1250×10mm3), which is currently under construction.

Status of the TORCH time-of-flight detector

The TORCH time-of-flight detector is designed for large-area coverage, up to 30 m2, to provide particle identification between 2–10 GeV/c momentum over a flight distance of 10 m. The arrival times from Cherenkov photons produced within a quartz radiator plate of 10 mm thickness are combined to achieve a 15 ps time-of-flight resolution per incident particle. Micro-Channel Plate Photomultiplier Tube (MCP-PMT) detectors of 53 × 53 mm2 active area have been developed with industrial partners for the TORCH application. The MCP-PMT is read out using charge division to give a 128 × 8 effective granularity. Laboratory results of development MCP-PMTs will be described, and testbeam studies using a small-scale TORCH prototype module will be presented.

Latest results from the TORCH R&D Project

TORCH (Timing Of internally Reflected CHerenkov photons) is a precision time-of-flight detector for particle identification at low momentum. It uses Cherenkov photons produced by charged particles passing through a quartz radiator plate. Some of these photons propagate by total internal reflection, they emerge at the edges and are subsequently focused onto photon detectors. The recorded positions and arrival times of the photons are used to precisely reconstruct their trajectory and propagation time in the quartz. This allows to determine the crossing time of the particles through the plate. The TORCH design requires the development of fast photon detectors with fine and asymmetric anode segmentation. The overall per-photon time precision must be better than 70 ps after signal processing and photon path reconstruction in the quartz. In addition, the photon detectors must survive several years of high illumination levels. The on-going R&D programme aims at demonstrating the TORCH basic concept through the realization of a detector module equipped with custom photon detectors featuring the required granularity and lifetime, with dedicated fast front-end electronics and with high-quality quartz radiator and focussing optics. This paper will report on the latest TORCH results achieved in the laboratory and in charged particle beam tests. It will also introduce the developments towards a full-scale module prototype.

The TORCH detector R&D: Status and perspectives

TORCH (Timing Of internally Reflected CHerenkov photons) is a time-of-flight detector for particle identification at low momentum. It has been originally proposed for the LHCb experiment upgrade. TORCH is using plates of quartz radiator in a modular design. A fraction of the Cherenkov photons produced by charged particles passing through this radiator propagate by total internal reflection, they emerge at the edges and are subsequently focused onto fast, position-sensitive single-photon detectors. The recorded position and arrival time of the photons are used to precisely reconstruct their trajectory and propagation time in the quartz. The on-going R&D programme aims at demonstrating the TORCH basic concept through the realization of a full detector module and has been organized on the following main development lines: micro-channel plate photon detectors featuring the required granularity and lifetime, dedicated fast front-end electronics preserving the picosecond timing information provided by single photons, and high-quality quartz radiator and focussing optics minimizing photon losses. The present paper reports on the TORCH results successfully achieved in the laboratory and in charged particle beam tests. It will also introduce the latest developments towards a final full-scale module prototype.

New Fast Interaction Trigger for ALICE

The LHC heavy-ion luminosity and collision rate from 2021 onwards will considerably exceed the design parameters of the present ALICE forward trigger detectors and the introduction of the Muon Forward Tracker (MFT) will significantly reduce the space available for the new trigger detectors. To comply with these conditions a new Fast Interaction Trigger (FIT) will be built. FIT will be the main forward trigger, luminometer, and interaction-time detector. It will also determine multiplicity, centrality, and reaction plane of heavy-ion collisions. FIT will consist of two arrays of Cherenkov quartz radiators with MCP-PMT sensors and of a plastic scintillator ring. By increasing the overall acceptance of FIT, the scintillator will improve centrality and event plane resolution. It will also add sensitivity for the detection of beam-gas events and provide some degree of redundancy. FIT is currently undergoing an intense R&D and prototyping period. It is scheduled for installation in ALICE during 2020.

TORCH - Cherenkov and Time-of-Flight PID Detector for the LHCb Upgrade at CERN

TORCH is a large-area precision time-of-flight detector, based on Cherenkov light production and propagation in a quartz radiator plate, which is read out at its edges. TORCH is proposed for the LHCb experiment at CERN to provide positive particle identification for kaons, and is currently in the Research-and-Development phase. A brief overview of the micro-channel plate photon sensor development, the custom-made electronics, and an introduction to the current test beam activities is given. Optical readout solutions are presented for the potential use of BaBar DIRC bar boxes as part of the TORCH configuration in LHCb.

The TORCH time-of-flight detector

The TORCH time-of-flight detector is being developed to provide particle identification between 2 and 10GeV/c momentum over a flight distance of 10m. TORCH is designed for large-area coverage, up to 30m2, and has a DIRC-like construction. The goal is to achieve a 15ps time-of-flight resolution per incident particle by combining arrival times from multiple Cherenkov photons produced within quartz radiator plates of 10mm thickness. A four-year R&D programme is underway with an industrial partner (Photek, UK) to produce 53×53mm2 Micro-Channel Plate (MCP) detectors for the TORCH application. The MCP-PMT will provide a timing accuracy of 40ps per photon and it will have a lifetime of up to at least 5Ccm−2 of integrated anode charge by utilizing an Atomic Layer Deposition (ALD) coating. The MCP will be read out using charge division with customised electronics incorporating the NINO chipset. Laboratory results on prototype MCPs are presented. The construction of a prototype TORCH module and its simulated performance are also described.

Particle identification with the TOP and ARICH detectors at Belle II

The SuperKEKB e+e− collider will provide 40 times higher instantaneous luminosity than the KEKB collider. The Belle II detector, located at the collision point, is the upgrade of the Belle detector. The particle identification will be improved by replacing the aerogel threshold counter with two new high performance Cherenkov detectors: the time-of-propagation (TOP) in the barrel region and the focusing aerogel (ARICH) in the forward region. The time-of-propagation sub-detector consists of quartz radiator bars and micro-channel plate photomultiplier tubes. The Cherenkov photons are produced and propagated through the quartz radiator, and after multiple internal reflections they are detected by the photomultiplier tubes. Photons with different Cherenkov angles reach different photomultiplier channels and arrive at different times. The time and the position convolution is used for the reconstruction of the Cherenkov angle. The focusing aerogel consists of a double layer aerogel radiator, an expansion volume and a photon detector. The aerogel thickness and the refractive indices of the two layers are optimized to focus the two light cones at the detection surface. The key features of these two detectors, the performance studies, and the construction progress are presented.

A novel Beam Halo Monitor for the CMS experiment at the LHC

A novel Beam Halo Monitor (BHM) has been designed and built for the CMS experiment at the LHC. It will provide an online, bunch-by-bunch measurement of background particles created by interactions of the proton beam with residual gas molecules in the vacuum chamber or with collimator material upstream of CMS. The BHM consists of two arrays of twenty detectors that are mounted around the outer forward shielding of the CMS experiment. Each detector is comprised of a cylindrical quartz radiator, optically coupled to a fast ultraviolet-sensitive photomultiplier tube from one end and painted black at the opposite end. Particles moving towards the photomultiplier tube will be detected with time resolution of a few nanoseconds, allowing to measure the flux of background particles produced upstream of CMS and suppress signals from collision-induced products. Monte Carlo simulations were performed to optimise the detector design. Prior to installation, the performance of the prototype detectors was measured in test beams quantifying the detector's direction-sensitive response and time resolution. The BHM was installed during the first LHC long shutdown (LS1) and is currently being commissioned. Design considerations, results from the test-beams supporting the design and the installation of the BHM in the CMS are presented.