Speaker
Description
We present the readout system being designed for triple-GEM detectors to be installed in 2019-2020 in the CMS muon endcap for HL-LHC. Beginning of 2017, 10 triple-GEMs have been installed in CMS. These detectors are read-out with the VFAT2 chip while its next version, the VFAT3, is under characterization. The rest of the readout system is very similar between the 2017 and the final version: on-detector FPGA board with GBTx and SCA, Versatile link and microTCA backend (CTP7). We will report on the first experience in CMS with VFAT2s as well as the status of the final system design.
Summary
In this contribution we will present the readout system being designed for triple-GEM detectors that should be installed in 2019-2020 in the CMS muon endcap system for the LHC high luminosity phase. Beginning of 2017, 10 triple-GEM detectors have been for the first time installed in CMS. These detectors are read-out with the VFAT2 chip while the next version of the chip, the VFAT3, is under characterization. The rest of the readout system is very similar between the 2017 and the final version: GEM Electronic Board (GEB), Opto-Hybrid board with on-detector FPGA, GBTx, SCA, Versatile link and micro-TCA backend (AMC13 and CTP7). We will report on the first experience in CMS with VFAT2s as well as the status of the final system design around the VFAT3.
The CMS triple-GEM has a trapezoidal shape, equipped with 1D readout, with dimensions 990 x 440-220 mm2. The readout strips are segmented in 24 sectors: 3 sectors along the azimuthal coordinate spanning 10° in φ x 8 sectors along the pseudo-rapidity (1.5<|η|<2.2). Each sector consists of 128 anode strips read-out by a new front-end chip being designed, the VFAT3. The readout system being designed takes full advantage of current generic developments introduced for the LHC upgrades; it is based on the use of CTP7 AMC boards host in micro-TCA crates for the off-detector electronics and the Versatile Link with the GBT chipset to link the front-end electronics to the micro-TCA boards. In addition the CMS AMC13 micro-TCA board will be used to interface the back-end electronics to the central CMS DAQ system. Finally the FEAST DC-DC converters are used to power the on-detector electronics.
In addition a few hardware components have to be developed specifically for this project: the GEM Electronic Board (GEB) and the Opto-Hybrid board. The GEB consists in a large multi-layer PCB board, matching the size of the Triple-GEM detector. The Opto-Hybrid is a small (typically 10 x 20 cm2) mezzanine, mounted on the center of the GEB, equipped with a Xilinx Virtex6 FPGA and the GBT chipsets. The Opto-Hybrid will collect the trigger and tracking data from the 24 VFAT3 chips and ensure the sparcification and the formatting of these data for the optical links. The data are transmitted from the VFAT3s to the Opto-hybrid through the GEB PCB at 320 MHz.
In January 2017 10 triple-GEM detectors equipped with the VFAT2 FE chips have been installed in CMS. In this contribution we will report on the lessons learned and on the first results gathered with this new system in CMS. Together with the characterization of the new VFAT3 chip, which started in March 2017, these results are very valuable to finalize the design for the final system. First results from the VFAT3 characterization and the status of the final CMS Triple-GEM readout system design will also be reported.
