Testbeam studies of a TORCH prototype detector

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Accelerators, spectrometers, detectors and associated equipment, 2018-11, Vol.908, p.256-268
• Main Authors: Brook, N.H., García, L. Castillo, Conneely, T.M., Cussans, D., van Dijk, M.W.U., Föhl, K., Forty, R., Frei, C., Gao, R., Gys, T., Hancock, T.H., Harnew, N., Lapington, J., Milnes, J., Piedigrossi, D., Rademacker, J., García, A. Ros
• Format: Article
• Language: English
• Subjects: Cherenkov radiation; MCP-PMT; Particle identification; TORCH
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/j.nima.2018.07.023

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.