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) [Formula presented] 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

Test-beam performance of a TORCH prototype module

The TORCH time-of-flight detector is designed to provide a 15 ps timing resolution for charged particles, resulting in K/p (p/K) particle identification up to momentum of about 10 (15) GeV/c over a 10 m flight distance. Cherenkov photons, produced in a quartz plate of 10 mm thickness, are focused onto an array of micro-channel plate photomultipliers (MCP-PMTs) which measure the photon arrival times and spatial positions. A TORCH demonstrator module instrumented with a customised MCP-PMTs has been tested at the CERN PS. The useful implementation for the particle identification in the LHCb experiment requires single-photon time resolution of 70 ps. The timing performance and photon yields have been measured as a function of beam position in the radiator, giving measurements which are approaching the required resolution. A possible TORCH design of the particle identification system in the LHCb experiment has been simulated and its potential for high luminosity running has been evaluated

The TORCH time-of-flight detector

TORCH is a large-area time-of-flight (ToF) detector, proposed for the Upgrade-II of the LHCb experiment. It will provide charged hadron identification over a 2–20 GeV/c momentum range, given a 9.5m flight distance from the LHC interaction point. To achieve this level of performance, a 15ps timing resolution per track is required. A TORCH prototype module having a 1250×660×10mm3 fused-silica radiator plate and equipped with two MCP-PMTs has been tested in a 8GeV/c CERN test-beam. Single-photon time resolutions of between 70–100ps have been achieved, dependent on the beam position in the radiator. The measured photon yields agree with expectations

Performance of a prototype TORCH time-of-flight detector

TORCH is a novel time-of-flight detector, designed to provide charged particle identification of pions, kaons and protons in the momentum range 2–20 GeV/c over a 9.5 m flight path. A detector module, comprising a 10 mm thick quartz plate, provides a source of Cherenkov photons which propagate via total internal reflection to one end of the plate. Here, the photons are focused onto an array of custom-designed Micro-Channel Plate Photo-Multiplier Tubes (MCP-PMTs) which measure their positions and arrival times. The target time resolution per photon is 70 ps which, for 30 detected photons per charged particle, results in a 10–15 ps time-of-flight resolution. A 1.25 m length TORCH prototype module employing two MCP-PMTs has been developed, and tested at the CERN PS using a charged hadron beam of 8 GeV/c momentum. The construction of the module, the properties of the MCP-PMTs and the readout electronics are described. Measurements of the collected photon yields and single-photon time resolutions have been performed as a function of particle entry points on the plate and compared to expectations. These studies show that the performance of the TORCH prototype approaches the design goals for the full-scale detector

TORCH—a Cherenkov based time-of-flight detector

TORCH is an innovative high-precision time-of-flight system to provide particle identification in the difficult intermediate momentum region up to 10 GeV/c. It is also suitable for large-area applications. The detector provides a time-of-flight measurement from the imaging of Cherenkov photons emitted in a 1 cm thick quartz radiator. The photons propagate by total internal reflection to the edge of the quartz plate and are then focused onto an array of photon detectors at the periphery. A time-of-flight resolution of about 10-15 ps per incident charged particle needs to be achieved to allow a three sigma kaon-pion separation up to 10 GeV/c momentum for the TORCH located 9.5 m from the interaction point. Given ~30 detected photons per incident charged particle, this requires measuring the time-of-arrival of individual photons to about 70 ps. This paper will describe the design of a TORCH prototype involving a number of ground-breaking and challenging techniques

TORCH — a Cherenkov-based time-of-flight detector

TORCH is an innovative high-precision time-of-flight system to provide particle identification in the difficult intermediate momentum region up to 10 GeV/c. It is also suitable for large-area applications. The detector provides a time-of-flight measurement from the imaging of Cherenkov photons emitted in a 1 cm thick quartz radiator. The photons propagate by total internal reflection to the edge of the quartz plate, where they are focused onto an array of photon detectors at the periphery. A time-of-flight resolution of about 10-15 ps per incident charged particle needs to be achieved for a three sigma kaon-pion separation up to 10 GeV/c momentum for the TORCH located 9.5 m from the interaction point. Given ∼ 30 detected photons per incident charged particle, this requires measuring the time-ofarrival of individual photons to about 70 ps. This paper will describe the design of a TORCH prototype involving a number of ground-breaking and challenging techniques

TORCH - A Cherenkov based time-of-flight detector

TORCH is an innovative high-precision time-of-flight system to provide particle identification in the difficult intermediate momentum region up to 10 GeV/c. It is also suitable for large-area applications. The detector provides a time-of-flight measurement from the imaging of Cherenkov photons emitted in a 1 cm thick quartz radiator. The photons propagate by total internal reflection to the edge of the quartz plate and are then focused onto an array of photon detectors at the periphery. A time-of-flight resolution of about 10-15 ps per incident charged particle needs to be achieved to allow a three sigma kaon-pion separation up to 10 GeV/c momentum for the TORCH located 9.5 m from the interaction point. Given ~30 detected photons per incident charged particle, this requires measuring the time-of-arrival of individual photons to about 70 ps. This paper will describe the design of a TORCH prototype involving a number of ground-breaking and challenging techniques

The TORCH time-of-flight detector

The TORCH detector is a time-of-flight system that is being developed for use in particle physics experiments with the aim of providing particle identification, over a wide area, in the momentum range 2 to 10 GeV/c. The detector exploits prompt Cherenkov light produced by charge particles traversing a 10 mm thick quartz plate. Photons propagate via total-internal reflection and are focussed onto a detector plane comprising position-sensitive micro-channel plate photomultiplier (MCP-PMT) detectors. The goal is to achieve a resolution of 15 ps per particle by combining information from around 30 detected photons, given a single-photon resolution of 70 ps. The MCP-PMT detectors have been developed with a commercial partner (Photek), leading to the delivery of a square tube with a 53-by-53 mm active area and 8-by-128 pixel equivalent. A small-scale TORCH demonstrator has been operated in beam tests and preliminary results indicate a single-photon resolution better than 100 ps. Progress towards a larger-scale system with 11 MCP-PMTs is presented

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