A Time-of-Flight Hodoscope Saving the Number of Photomultipliers

Results of measurements of the performances of a time-of-flight hodoscope consisting of 16 slabs of plastic scintillator, 90×4×1 cm3 each, viewed by only 8 (instead of 32) photomultipliers are described. The slabs are coupled to the photomultipliers in such a way that they are considered as the elements of a square matrix of rank 4. Thus only 2×4 photomultipliers are needed to identify unambiguously each of the 16 slabs, if only a particle at a time has to be detected. By means of a very simple electronics we obtained a local time-of-flight resolution of 570 ps fwhm and a spatial resolution along each slab of 5 cm fwhm. The cross-talk due to unrecognized events was less than 5%.