The CMS first level muon trigger system is based on information from the Resistive Plate Chambers (RPC), the Drift Tubes (DTBX) and the Cathode Strip Chambers (CSC). The trigger hardware consists of several components which are described in [1]. Fig. 1 shows a block diagram with the functional relations between the different components. The corresponding simulation software in CMSIM [2] is available for the RPC based trigger and for parts of the DTBX/CSC based trigger. Since recently also a first version of the Muon Track Finder simulation software is available which allows us to test the whole DTBX trigger chain for the first time. The two trigger systems have been tested together with a first implementation of a Global Muon Trigger algorithm combining the results from the RPC and DTBX systems to improve the overall muon trigger efficiency.
The philosophy of the two systems compared here is different. The RPC trigger
logic is based on a global view of all RPC detector elements. A pattern of hits
recorded by RPC carries information about the bending in the magnetic field,
and can be used to determine 
of the track. This is done by comparison with a predefined set of patterns
corresponding to various .
In contrast
the DTBX/CSC trigger works by processing the information from each chamber
locally. As a result a vector per muon station is delivered. Vectors from
different stations are collected by the Muon Track Finder (MTF) which combines
them to form a muon track and assign a
value.
The purpose of this study is to show the efficiency of the trigger to identify
muons and to measure their transverse momenta,
and
, pinning down
possible local inefficiencies of the DTBX and RPC trigger system. It should
also be demonstrated how the information from the two trigger systems - DTBX
and RPC - can be combined to improve the overall muon trigger efficiency.
After a short description of the simulation process, the trigger logic and hardware features of the RPC and DTBX trigger systems are discussed. This is followed by an investigation of the performance of the RPC and DTBX trigger systems and finally we show how to improve the results by using the Global Muon Trigger algorithm.