Performance of a prototype TORCH time-of-flight detector

Bhasin, S, Blake, T, Brook, N ORCID: https://orcid.org/0000-0002-1818-0113, Cicala, MF, Conneely, T, Cussans, D, van Dijk, MWU, Forty, R, Frei, C, Gabriel, EPM, Gao, R, Gershon, T, Gys, T, Hadavizadeh, T, Hancock, TH, Harnew, N, Jones, T, Kreps, M, Milnes, J, Piedigrossi, D, Rademacker, J and Smallwood, JC (2023) Performance of a prototype TORCH time-of-flight detector. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment, 1050. p. 168181. ISSN 0168-9002

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Abstract

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.