NEW GENERATION OF CHERENKOV COUNTERS

Experimental results with a parallel plate avalanche chamber (PPAC) having a CsI photocathode and pad array readout are reported. High gains in excess of 105 have been obtained with He gas at atmospheric pressure and traces of CH4 or CF4 quencher. Such light gas mixtures extend the transparency for the Cherenkov light to the extreme UV region and allow detector operation with very low sensitivity to the ionization produced by minimum ionizing particles. A hadron blind detector (HBD) is discussed which exploits the broad photon energy bandwidth (almost-equal-to 10 eV) and the high Cherenkov threshold (p(pi) = 15 GeV). This fast detector, since it has a good spatial resolution, can be used at the future Large Hadron Collider (LHC) or the Superconductivity Super Collider (SSC) either as an efficient electron tagger, rejecting hadrons faking electrons in the calorimeter, or as a pretracker giving fast electron and high-energy muon signature and momentum estimation. Other potential applications in the domain of Cherenkov light detection are also discussed.