Studying the timing characteristics of counters for the trigger hodoscope of charged particles for the NA62 experiment

Abstract

The time resolution of the prototype counters for a new charged particle hodoscope for the NA62 experiment has been measured. The prototype scintillation counters with dimensions of 90 × 90, 100 × 100, 150 × 150, 180 × 100, and 270 × 100 mm are investigated. Several variants of direct light collection from a scintillator brink and a corner are considered, as well as light collection using wavelength-shifting (WLS) fibers. Silicon photodiodes from the Centre of Perspective Technologies and Apparatuses (CPTA) and SensL, as well as a compact R7400U photomultiplier tube were used as photodetectors. An R7899-20 photomultiplier tube with a high quantum efficiency in the green spectral region is used as a reference counter. The measurements have been taken with cosmic muons and the beam halo of beamline 21 in the zone of the OKA experiment. The time resolution of a 100 × 100 mm cell, averaged over the area, is 590 ± 10 ps in the case of the WLS-fiber readout and 260 ± 25 ps in the case of direct light collection from the scintillator brink.