  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 10mm 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.
