Large-Area Sandwich Veto Detector with WLS Fibre Readout for Hadron Spectroscopy at COMPASS
Keywords
Lead-plastic sandwich_s19 WLS readout_s19 Veto trigger_s19 MC simulation
Abstract
A sandwich detector composed of scintillator and steel-covered lead layers was introduced in the fixed-target COMPASS experiment at CERN for vetoing events not completely covered by the two-stage magnetic spectrometer. Wavelength shifting fibres glued into grooves in the scintillator tiles serve for fast read-out. Minimum ionizing particles impinging on the $2 textrm{m} times 2 textrm{m}$ detector outside of a central hole, sparing the spectrometer_s14s entry, are detected with a probability of 98%. The response to charged particles and photons is modeled in detail in Monte Carlo calculations. Figures of merit of the veto trigger in $190 textrm{GeV}/c$ $pi^- _s16 p$ (or nucleus) experiments are an enrichment of exclusive events in the recorded data by a factor of 3.5 and a false-veto probability of 1%.
