Fast ring imaging detectors for forward B collider experiments

A good hadron identification system is a crucial element in an experiment designed to measure CP violation asymmetries in B decays. In particular the reactions B → π+π- and B → K±π-+ need to be disentangled with high accuracy. note Thet the kinematics of the reactions B → π+π- and B → K±π-+ are so similar that conventional particle identification approaches have no chance to provide adequate separation between these two decay channels. An experiment designed to detect B's produced in the forward direction in a hadron collider has the advantage of having enough longitudinal space to allow the insertion of a fast Ring Imaging Cherenkov (RICH) detector, which should suit both the particle identification needs and the processing speed required at SSC. In order to set the scale for the momentum coverage needed, simulation studies have indicated that most particles coming from B decays at SSC have a momentum smaller or roughly equal to 100 GeV. In the next section the performance expected for a typical fast RICH detector suitable for this application is discussed. The fast RICH detector considered in this present study can be located downstream of the tracking system. Tha authors show that a single gaseous fast RICH can accomplish the physics goals, namely that the lowest momentum at which the particle species need to be unambiguously identified is of the order of a few GeV, corresponding to the threshold of the most common gas radiators