Readout and Trigger Electronics for the Triple-GEM Detectors of the CMS GE2/1 System
2020 March 09
The Triple Gas Electron Multiplication (GEM) technology has been adopted for the upgrade of the forward muon detector system at the CMS experiment for the future High-Luminosity phase of the Large Hadron Collider (LHC) at CERN. The GE2/1 subdetector comprises 72 chambers that will be in stalled after the second LHC Long Shutdown. The main goal of these chambers is to improve muon momentum measurements and triggering capabilities in the 1.6 < |η| < 2.4 pseudo-rapidity region. The GE2/1 chambers are segmented in 4 modules with 12 sectors in each module, and each sector is composed of 128 radial strips. The strips are read out by the front-end VFAT3 ASIC. It has 128 channels, each with a charge sensitive preamplifier, shaper and a discriminator. Each module is equipped with the OptoHybrid (OH) board that provides the readout and trigger interfaces for 12 VFAT3 ASICs. The OH board uses CERN designed GigaBit Transceivers (GBT) for the readout path. VFAT3 ASICs also provide trigger information that allows the OH to build trigger clusters using the Xilinx Artix-7 FPGA and to transmit these clusters to the back-end Trigger Processor and to the local Cathode Strip Chamber Trigger Motherboard to improve local trigger efficiency at an early stage of the trigger processing. The back-end electronics will use the ATCA Trigger Processor farm; it will send the data to the Endcap Muon Track Finder and to the CMS DAQ system. In this presentation, we report on progress on the GE2/1 electronics and results from the first demonstrator tests performed at CERN in 2019, and we outline our future design and production plans.