The series of upgrades to the Large Hadron Collider, culminating in the High Luminosity Large Hadron Collider, will enable a significant expansion of the physics program of the CMS experiment. ...However, the accelerator upgrades will also make the experimental conditions more challenging, with implications for detector operations, triggering, and data analysis. The luminosity of the proton–proton collisions is expected to exceed 2–3×1034 cm−2s−1 for Run 3 (starting in 2022), and it will be at least 5×1034 cm−2s−1 when the High Luminosity Large Hadron Collider is completed for Run 4. These conditions will affect muon triggering, identification, and measurement, which are critical capabilities of the experiment. To address these challenges, additional muon detectors are being installed in the CMS endcaps, based on Gas Electron Multiplier technology. For this purpose, 161 large triple-Gas Electron Multiplier detectors have been constructed and tested. Installation of these devices began in 2019 with the GE1/1 station and will be followed by two additional stations, GE2/1 and ME0, to be installed in 2023 and 2026, respectively. The assembly and quality control of the GE1/1 detectors were distributed across several production sites around the world. We motivate and discuss the quality control procedures that were developed to standardize the performance of the detectors, and we present the final results of the production. Out of 161 detectors produced, 156 detectors passed all tests, and 144 detectors are now installed in the CMS experiment. The various visual inspections, gas tightness tests, intrinsic noise rate characterizations, and effective gas gain and response uniformity tests allowed the project to achieve this high success rate.
The upgrade of the CMS detector for the high luminosity LHC (HL-LHC) will include gas electron multiplier (GEM) detectors in the end-cap muon spectrometer. Due to the limited supply of large area GEM ...detectors, the Korean CMS (KCMS) collaboration had formed a consortium with Mecaro Co., Ltd. to serve as a supplier of GEM foils with area of approximately 0.6m2. The consortium has developed a double-mask etching technique for production of these large-sized GEM foils. This article describes the production, quality control, and quality assessment (QA/QC) procedures and the mass production status for the GEM foils. Validation procedures indicate that the structure of the Korean foils are in the designed range. Detectors employing the Korean foils satisfy the requirements of the HL-LHC in terms of the effective gain, response uniformity, rate capability, discharge probability, and hardness against discharges. No aging phenomena were observed with a charge collection of 82mCcm−2. Mass production of KCMS GEM foils is currently in progress.
The high-luminosity phase of the Large Hadron Collider (HL-LHC) will result in ten times higher particle background than measured during the first phase of LHC operation. In order to fully exploit ...the highly-demanding operating conditions during HL-LHC, the Compact Muon Solenoid (CMS) Collaboration will use Gas Electron Multiplier (GEM) detector technology. The technology will be integrated into the innermost region of the forward muon spectrometer of CMS as an additional muon station called GE1∕1. The primary purpose of this auxiliary station is to help in muon reconstruction and to control level-1 muon trigger rates in the pseudo-rapidity region 1.6≤|η|≤2.2. The new station will contain trapezoidal-shaped GEM detectors called GE1∕1 chambers. The design of these chambers is finalized, and the installation is in progress during the Long Shutdown phase two (LS-2) that started in 2019. Several full-size prototypes were built and operated successfully in various test beams at CERN. We describe performance measurements such as gain, efficiency, and time resolution of these prototype chambers, developed after years of R&D, and summarize their behavior in different gas compositions as a function of the applied voltage.
This contribution introduces a new type of Micropattern Gaseous Detector, the Fast Timing Micropattern (FTM) detector, utilizing fully Resistive WELL structures. The structure of the prototype will ...be described in detail and the results of the characterization study performed with an X-ray gun will be presented, together with the first results on time resolution based on data collected with muon/pion test beams.
VFAT3 is the front-end ASIC designed specifically for the readout of GEM detectors within the CMS experiment during the high luminosity phase of the LHC at CERN. This paper presents the analog and ...digital design plus the measured functional and characterization results. Key design goals were optimization to GEM charge characteristics maximizing signal to noise, timing resolution and operation at high particle rate. There are 128 front-end channels comprising preamplifier, shaper and constant fraction discriminator (CFD). Features include programmable polarity (for use with gaseous MPGD or silicon detectors), programmable gain (for linearity 9.5 fC, 28 fC and 55 fC) and programmable shaping times (15 ns, 25 ns, 36 ns and 45 ns), plus the CFD reducing time walk to less than 0.4 ns within 3 fC to 30 fC of input charge, optimizing timing resolution. An internal calibration circuit allows calibration of each channel with "GEM like" or "Silicon like" input pulses, each having programmable amplitude, polarity and phase. The ENC measures 620 e + 33 e/pF in high gain. The hit rate capability is demonstrated to 2 MHz per channel. VFAT3 has 2 output paths; the first (Trigger Path) provides hit information for every LHC clock cycle. The second (Data Path) provides data packets upon receipt of a trigger, each data packet contains hit information and time stamps. The chip can operate with trigger latencies up to 25.6 µs and is capable of receiving consecutive triggers. VFAT3 can operate with up to 2 MHz trigger rate in default mode and has data packet zero suppression capabilities to go beyond this rate. An internal dedicated Comm-Port allows communication to and from the chip. Additional features include channel input protection, internal/external temperature measurement and design for a radiation environment. The design and measurements presented demonstrate the VFAT3 capability as a complete binary front-end readout ASIC optimized for GEM detectors in the high luminosity LHC.
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