Abstract
The CMS experiment will be upgraded for operation at the HighLuminosity LHC to maintain and extend its physics performance under extreme pileup conditions. Upgrades will include an entirely new tracking system, supplemented by a track finder processor providing tracks at Level-1, as well as a high-granularity calorimeter in the endcap region. New front-end and back-end electronics will also provide the Level-1 trigger with high-resolution information from the barrel calorimeter and the muon systems. The upgraded Level-1 processors, based on powerful FPGAs, will be able to carry out sophisticated feature searches with resolutions often similar to the offline ones, while keeping pileup effects under control. In this paper, we discuss the feasibility of a system capturing Level-1 intermediate data at the beam-crossing rate of 40 MHz and carrying out online analyzes based on these limited-resolution data. This 40 MHz scouting system would provide fast and virtually unlimited statistics for detector diagnostics, alternative luminosity measurements and, in some cases, calibrations. It has the potential to enable the study of otherwise inaccessible signatures, either too common to fit in the Level-1 accept budget, or with requirements which are orthogonal to “mainstream” physics, such as long-lived particles. We discuss the requirements and possible architecture of a 40 MHz scouting system, as well as some of the physics potential, and results from a demonstrator operated at the end of Run-2 using the Global Muon Trigger data from CMS. Plans for further demonstrators envisaged for Run-3 are also discussed.
Highlights
For its High-Luminosity phase of operation, currently planned to start in 2027, the Large Hadron Collider at CERN will be upgraded to provide an instantaneous luminosity of up to 7.5x1034/cm2/s resulting in a pile-up of up to 200 inelastic collisions per event
In order to cope with these conditions, the Compact Muon Solenoid (CMS) experiment [1] will undergo a major upgrade including an entirely new tracking system with a track finder providing tracks at Level-1 [2], a new high-granularity calorimeter in the endcap region [3], and new readout electronics for the barrel calorimeter and muon systems providing finer granularity
CMS will continue to employ two trigger levels: a Level-1 trigger based on state-of-the-art FPGAs, selecting events at 750 kHz and a high-level trigger running on a farm of heterogeneous compute nodes performing the second level of selection in software
Summary
Gilbert Badaro8, Ulf Behrens6, James Branson2, Philipp Brummer1,c, Sergio Cittolin2, Diego Da Silva-Gomes3,b, Georgiana-Lavinia Darlea4, Christian Deldicque1, Marc Dobson1, Nicolas Doualot3,b, Jonathan Richard Fulcher1, Dominique Gigi1, Maciej Gladki1, Frank Glege1, Dejan Golubovic1, Guillelmo Gomez-Ceballos4, Jeroen Hegeman1, Thomas Owen James1, Wei Li6, Audrius Mecionis3,a, Frans Meijers1, Emilio Meschi1, Remigius K. Mommsen3, Keyshav Mor1, Srecko Morovic2, Luciano Orsini1, Ioannis Papakrivopoulos5,b, Christoph Paus4, Andrea Petrucci2, Marco Pieri2, Dinyar Rabady1, Kolyo Raychinov1, Attila Racz1, Alvaro Rodriguez-Garcia1, Hannes Sakulin1, Christoph Schwick1, Dainius Simelevicius7,b, Panagiotis Soursos1, Andre Stahl6, Mantas Stankevicius3,a, Uthayanath Suthakar1, Cristina Vazquez-Velez1, Awais Zahid1, Petr Zejdl3,b
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