Speaker
Description
The High-Luminosity upgrade of the Large Hadron Collider (HL-LHC) introduces new challenges for experiments like CMS by substantially increasing the collision rate. This intensified luminosity will particularly affect the forward regions of the CMS detector, where particle flux will be most intense. To meet this challenge, CMS is deploying new Gas Electron Multiplier (GEM) stations—GE1/1, GE2/1, and ME0—in its forward muon system to enhance tracking and triggering capabilities in these highrate environments. The GEM stations require highly advanced, two-layer printed circuit boards (PCBs) for efficient signal readout and processing, which are specifically designed for the demands of HL-LHC. This report details the PCB-based readout system and validates its readiness for HL-LHC conditions. The GEM detector is essential to the CMS muon system, with the first station, GE1/1, already installed during the second long shutdown (LS2) to cover the pseudorapidity range from 1.55 to 2.18. Production is ongoing for two additional stations: GE2/1, which will span the range from 1.6 to 2.4, and ME0, covering 2.0 to 2.8. Operating in high-radiation environments presents unique challenges, particularly for signal readout systems like PCBs. To address these, the readout materials are specifically tailored for the Phase 2 upgrade of the CMS GEM detectors, with radiation-hardened substrates to minimize contamination and ensure signal fidelity in high-radiation zones. The fabrication of the PCBs involves advanced techniques to meet the precision demands of HL-LHC. Processes such as CNC drilling ensure the accuracy and uniformity of boreholes, and electroless copper plating reinforces the copper layers. Techniques including outer layer photo printing, microetching for surface treatment, and resist stripping ensure micron-level precision and high-density signal tracks, optimizing overall detector performance. To extend PCB lifespan, chromite passivation is applied after component assembly. Rigorous validation procedures are essential to guarantee PCB reliability under the extreme conditions of the CMS experiment. Mechanical and dimensional inspections, electrical testing, structural analysis, and signal integrity assessments identify potential manufacturing defects and inconsistencies. A thermal stress test evaluates the resistance of the PCB’s base material and copper layers to temperature fluctuations, ensuring long-term stability and functionality. This summary focuses on the properties, fabrication processes, and performance validation of PCBs designed for high-flux radiation environments in the CMS GEM detectors, ensuring readiness for the HL-LHC era.
| Field of contribution | Experiment |
|---|
