Beam test performance of a closed microstrip gas chamber module for the CMS forward tracker

We built and tested a closed MSGC module for the CMS forward tracker with trapezoidal strip patterns on 300 m DESAG263 glass substrates produced by OPTIMASK. In the 100 GeV X5 --beam at CERN, we investigated the behaviour of this module foreseen for four wedge shaped substrates, 512 anode strips each. Good separation of signal and noise was achieved and efficiencies reached 97%. The variation of gain across the strip pattern was examined. 1 Introduction Microstrip gas chambers (MSGCs) [1, p.28] are foreseen to set up the outer layers of the inner tracking system in CMS [1]. Since their introduction by A. Oed [2] they have attracted a lot of interest due to good position-- and two-track resolution, high rate capability and lower costs compared to silicon detectors. In this note we concentrate on the mechanical setup of an MSGC module designed for the CMS forward tracker. Therefore we used trapezoidal strip patterns on wegde shaped glass substrates and built a banana--shaped detector ..