Ghosts Buster for the RPC Based Muon Trigger

An effective solution to the ghosts problem of the CMS muon RPC trigger is proposed. The implementation of the algorithm requires a replacement of the first sorter level by a dedicated veto layer, for phi-wise sorting and inserting an additional veto layer before eta-wise sorting . It is shown also, that the effect of clusters in the RPC detector can cause a significant grow of the trigger rate. Therefore a careful measurement of this size is necessary.