CERN Accelerating science

CMS Note
Report number	CMS-CR-2017-030
Title	The CMS Data Acquisition - Architectures for the Phase-2 Upgrade
Author(s)	Andre, Jean-Marc Olivier (Fermilab) ; Behrens, Ulf (DESY) ; Branson, James (UC, San Diego) ; Brummer, Philipp Maximilian (CERN) ; Chaze, Olivier (CERN) ; Cittolin, Sergio (UC, San Diego) ; Contescu, Cristian (Fermilab) ; Craigs, Benjamin Gordon (CERN) ; Darlea, Georgiana Lavinia (MIT) ; Deldicque, Christian (CERN) ; Demiragli, Zeynep (MIT) ; Dobson, Marc (CERN) ; Doualot, Nicolas (Fermilab) ; Erhan, Samim (UCLA) ; Fulcher, Jonathan F ; Gigi, Dominique (CERN) ; Michail Gladki (CERN) ; Glege, Frank (CERN) ; Gomez Ceballos, Guillelmo (MIT) ; Hegeman, Jeroen Guido (CERN) ; Holzner, Andre Georg (UC, San Diego) ; Janulis, Mindaugas (Vilnius U. ; CERN) ; Jimenez Estupinan, Raul (Zurich, ETH) ; Masetti, Lorenzo (CERN) ; Meijers, Franciscus (CERN) ; Meschi, Emilio (CERN) ; Mommsen, Remigius (Fermilab) ; Morovic, Srecko (Fermilab) ; O'Dell, Vivian (Fermilab) ; Orsini, Luciano (CERN) ; Paus, Christoph Maria Ernst (MIT) ; Petrova, Petia (ISER, Sofia ; CERN) ; Pieri, Marco (UC, San Diego) ; Racz, Attila (CERN) ; Reis, Thomas (CERN) ; Sakulin, Hannes (CERN) ; Schwick, Christoph (CERN) ; Simelevicius, Dainius (Vilnius U. ; CERN) ; Zejdl, Petr (Fermilab ; CERN)
Publication	2017
Imprint	10 Feb 2017
Number of pages	8
In:	J. Phys.: Conf. Ser. 898 (2017) 032019
In:	22nd International Conference on Computing in High Energy and Nuclear Physics, CHEP 2016, San Francisco, Usa, 10 - 14 Oct 2016, pp.032019
DOI	10.1088/1742-6596/898/3/032019
Subject category	Detectors and Experimental Techniques
Accelerator/Facility, Experiment	CERN LHC ; CMS
Abstract	The upgraded High Luminosity LHC, after the third Long Shutdown (LS3), will provide an instantaneous luminosity of $7.5\times10^{34}$ cm$^{-2} s^{-1}$ (levelled), at the price of extreme pileup of up to 200 interactions per crossing. In LS3, the CMS Detector will also undergo a major upgrade to prepare for the phase-2 of the LHC physics program, starting around 2025. The upgraded detector will be read out at an unprecedented data rate of up to 50 Tb/s and an event rate of 750 kHz. Complete events will be analysed by software algorithms running on standard processing nodes, and selected events will be stored permanently at a rate of up to 10 kHz for offline processing and analysis. In this paper we discuss the baseline design of the DAQ and HLT systems for the 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. Implications on hardware and infrastructure requirements for the DAQ "data center" are analysed. Emerging technologies for data reduction are considered. Novel possible approaches to event building and online processing, inspired by trending developments in other areas of computing dealing with large masses of data, are also examined. We conclude by discussing the opportunities offered by reading out and processing parts of the detector, wherever the front-end electronics allows, at the machine clock rate (40 MHz).
Copyright/License	publication: (License: CC-BY-3.0)

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