Operation and Performance of a new microTCA-based CMS Calorimeter Trigger in LHC Run 2

Abstract

The Large Hadron Collider (LHC) at CERN is currently increasing the instantaneous luminosity for p-p collisions. In LHC Run 2, the center-of-mass energy has gone from 8 to 13 TeV and the instantaneous luminosity will approximately double for proton collisions. This will make it even more challenging to trigger on interesting events since the number of interactions per crossing (pileup) and the overall trigger rate will be significantly larger than in LHC Run 1. The Compact Muon Solenoid (CMS) experiment has installed the second stage of a two-stage upgrade to the Calorimeter Trigger to ensure that the trigger rates can be controlled and the thresholds kept low, so that physics data will not be compromised. The stage-1, which replaced the original CMS Global Calorimeter Trigger, operated successfully in 2015. The completely new stage-2 has replaced the entire calorimeter trigger in 2016 with AMC form-factor boards and optical links operating in a microTCA chassis. It required that updates to the calorimeter back-ends, the source of the trigger primitive data, were also fully installed and operational. The stage-2 system's boards use Xilinx Virtex 7 690 FPGAs and have hundreds of links operating at up to 10 Gbps to maximize data throughput. In addition, a new trigger time-multiplexed architecture was implemented and extensive firmware and software development was necessary. The final commissioning, operation, and performance of the stage-2 calorimeter trigger in 2016 proton collisions will be presented, as well as the expectations of CMS for the remainder of LHC Run 2