https://doi.org/10.1051/epjconf/202532000002
CMS ECAL: Meeting the trigger performance challenges of Run 3
Northeastern University
* e-mail: john.dervan@cern.ch
Published online: 7 March 2025
The CMS electromagnetic calorimeter (ECAL) at the CERN LHC is a high-resolution crystal calorimeter equipped with fast digital signal processing algorithms for measuring the energy and timing of calorimeter deposits. These trigger primitives are sent to the Level-1 trigger system at a rate of 40 MHz to help decide whether to store the event data offline. This paper summarizes the ECAL trigger performance during LHC Run 3 (2022+), highlighting enhanced calibration methods for trigger primitives. A key focus is the commissioning of a new automated procedure for deriving, validating, and deploying time-dependent response corrections using in-situ measurements from a dedicated laser monitoring system. Additionally, the rejection of unwanted large signals (“spikes”) caused by hadronic deposits on the APD photodetectors in the ECAL barrel region (<η< 1.48) has been a persistent issue since 2009. The evolution of spike rejection techniques in ECAL’s on-detector and o↵-detector electronics, along with the potential of currently unused features of the ECAL electronics to further enhance spike rejection, will be discussed.
© The Authors, published by EDP Sciences, 2025
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
