Design of a disc DIRC detector for the WASA experiment

A Disc DIRC counter is foreseen for the WASA experiment at the COSY proton storage ring in Jülich. It shall improve the proton kinetic energy measurement in the forward direction by measuring the proton speed at the two per mille level. The segmentation into four quarter-discs allows to incline the radiator relative to the incoming particles. This lowers the threshold velocity for light propagation inside the DIRC radiator. The construction of a full-scale quarter disc prototype is envisaged within a year.