Picosecond timing of charged particles using the TORCH detector

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

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2 Citations (SciVal)


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.

Original languageEnglish
Article number166950
JournalNuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Early online date11 Jun 2022
Publication statusPublished - 1 Sept 2022

Bibliographical note

Funding Information:
The support is acknowledged of the Science and Technology Research Council, UK, grant number ST/P002692/1, of the European Research Council through an FP7 Advanced Grant (ERC-2011-AdG 299175-TORCH) and of the Royal Society, UK.


  • Particle identification
  • Time-of-flight detectors

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Instrumentation


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