CERN Accelerating science

CMS Note
Report number	CMS-CR-2018-099
Title	The CMS Data Acquisition System for the Phase-2 Upgrade
Author(s)	Hegeman, Jeroen Guido (CERN)
Publication	2018
Collaboration	CMS Collaboration
Imprint	25 Jun 2018
Number of pages	6
Presented at	21st IEEE Real Time Conference, Williamsburg, Va, United States Of America, 9 - 15 Jun 2018
Subject category	Detectors and Experimental Techniques
Accelerator/Facility, Experiment	CERN LHC ; CMS
Keywords	General
Abstract	During the third long shutdown of the CERN Large Hadron Collider, the CMS Detector will undergo a major upgrade to prepare for Phase-2 of the CMS physics program, starting around 2026. The upgraded CMS detector will be read out at an unprecedented data rate of up to 50Tb/s with an event rate of 750 kHz, selected by the level-1 hardware trigger, and an average event size of 7.4 MB. Complete events will be analyzed by the High-Level Trigger (HLT) using software algorithms running on standard processing nodes, potentially augmented with hardware accelerators. Selected events will be stored permanently at a rate of up to 7.5 kHz for offline processing and analysis. This paper presents the baseline design of the DAQ and HLT systems for Phase-2, taking into account the projected evolution of high speed network fabrics for event building and distribution, and the anticipated performance of general purpose CPU. In addition, some opportunities offered by reading out and processing parts of the detector data at the full LHC bunch crossing rate (40 MHz) are discussed.