Testbeam studies of a TORCH prototype detector

TL;DR

This paper reports on the development and testbeam validation of a small-scale prototype of the TORCH detector, demonstrating promising timing resolution and photon detection efficiency for particle identification in high-energy physics.

Contribution

It introduces a novel TORCH prototype with an innovative charge-sharing MCP-PMT readout, validated through CERN testbeams, advancing the detector's development for future large-scale applications.

Findings

Achieved single photon time resolution approaching 80 ps.

Photon counting efficiency agrees with GEANT4 simulations.

Prototype operated successfully with customised electronics at CERN.

Abstract

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 $660\times1250\times10~{\rm mm^3}$), which is currently under construction.