A Prototype Threshold Cherenkov Counter for DIRACM Bragadireanu,L Casano,E Cima,B Dulach,P Gianotti,C Guaraldo,MA Iliescu,A Lanaro,PL Sandri,C Petrascu,B Girolami,L Groza,A Kulikov,A Kuptsov,N Topilin,S Trusov