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  • Picosecond timing of charge...
    Cicala, M.F.; Bhasin, S.; Blake, T.; Brook, N.H.; Conneely, T.; Cussans, D.; van Dijk, M.W.U.; Forty, R.; Frei, C.; Gabriel, E.P.M.; Gao, R.; Gershon, T.; Gys, T.; Hadavizadeh, T.; Hancock, T.H.; Harnew, N.; Jones, T.; Kreps, M.; Milnes, J.; Piedigrossi, D.; Rademacker, J.; Smallwood, J.C.

    Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment, 09/2022, Letnik: 1038
    Journal Article

    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.