A hardware abstraction layer for the MicroTCA-based Global Trigger for the CMS experiment at CERN

Der Large Hadron Collider (LHC) am CERN bei Genf produziert mit einer Frequenz von 40 MHz Teilchenkollisionen. Jede dieser Kollisionen benötigt nachdem sie vom CMS Detektor aufgezeichnet worden ist etwa 1 MB an Speicher. Um diese enorme Menge an Daten zu reduzieren wurde ein komplexes Filter-System entwickelt. Die erste Stufe dieses Systems nimmt der Level-1 Trigger ein, der die Rate an aufgezeichneten Kollisionen auf 100 kHz reduziert. Diese Kollisionen können anschließend von einer großen Rechenfarm analysiert und weiter gefiltert werden. Der LHC wird in absehbarer Zukunft ausgebaut werden um Kollisionen mit noch mehr beteiligten Teilchen zu produzieren, was eine Verbesserung des Level-1 Triggers notwendig macht. Diese Arbeit beschäftigt sich mit den Plänen zu diesem Ausbau innerhalb des Global Trigger (GT) Projekts und führte schlussendlich zur Entwicklung einer hardware abstraction layer (HAL), die entfernten Zugriff auf Hardware-Register über Ethernet erlaubt wie auch abstrakte Elemente zur Verfügung stellt um die Information in den Registern zu repräsentieren. Abschließend wird eine Studie über die Effizienz des Global Muon Trigger präsentiert die zu Verbesserungen für die Datennahme ab dem Jahr 2011 geführt hat.The Large Hadron Collider (LHC) based at CERN near Geneva collides proton bunches at a rate of 40 MHz. Each collision produces approximately 1 MB of data in the Compact Muon Solenoid (CMS) detector. In order to reduce this event rate to a more manageable amount, a complex filter system was developed. The first stage of this filter is the so-called Level-1 trigger. This system reduces the incoming event rate to 100 kHz which can then be analyzed and filtered further in a massive computing farm. The LHC is scheduled to be upgraded to provide collisions with even more particles involved thus making an upgrade of the Level-1 trigger necessary. This thesis is concerned with the upgrade plans of the GlobalTrigger (GT) project and ultimately lead to the development ofa hardware abstraction layer (HAL) which can provide remote register-level access via Ethernet as well as abstract items to represent the information stored in the registers. Finally a study of the Global Muon Trigger (GMT) efficiency is presented

MiniDAQ-3: Providing concurrent independent subdetector data-taking on CMS production DAQ resources

The data acquisition (DAQ) of the Compact Muon Solenoid (CMS) experiment at CERN, collects data for events accepted by the Level-1 Trigger from the different detector systems and assembles them in an event builder prior to making them available for further selection in the High Level Trigger, and finally storing the selected events for offline analysis. In addition to the central DAQ providing global acquisition functionality, several separate, so-called “MiniDAQ” setups allow operating independent data acquisition runs using an arbitrary subset of the CMS subdetectors. During Run 2 of the LHC, MiniDAQ setups were running their event builder and High Level Trigger applications on dedicated resources, separate from those used for the central DAQ. This cleanly separated MiniDAQ setups from the central DAQ system, but also meant limited throughput and a fixed number of possible MiniDAQ setups. In Run 3, MiniDAQ-3 setups share production resources with the new central DAQ system, allowing each setup to operate at the maximum Level-1 rate thanks to the reuse of the resources and network bandwidth. Configuration management tools had to be significantly extended to support the synchronization of the DAQ configurations needed for the various setups. We report on the new configuration management features and on the first year of operational experience with the new MiniDAQ-3 system

The CMS Orbit Builder for the HL-LHC at CERN

The Compact Muon Solenoid (CMS) experiment at CERN incorporates one of the highest throughput data acquisition systems in the world and is expected to increase its throughput by more than a factor of ten for High-Luminosity phase of Large Hadron Collider (HL-LHC). To achieve this goal, the system will be upgraded in most of its components. Among them, the event builder software, in charge of assembling all the data read out from the different sub-detectors, is planned to be modified from a single event builder to an orbit builder that assembles multiple events at the same time. The throughput of the event builder will be increased from the current 1.6 Tb/s to 51 Tb/s for the HL-LHC orbit builder. This paper presents preliminary network transfer studies in preparation for the upgrade. The key conceptual characteristics are discussed, concerning differences between the CMS event builder in Run 3 and the CMS Orbit Builder for the HL-LHC. For the feasibility studies, a pipestream benchmark, mimicking event-builder-like traffic has been developed. Preliminary performance tests and results are discussed

Towards a container-based architecture for CMS data acquisition

The CMS data acquisition (DAQ) is implemented as a service-oriented architecture where DAQ applications, as well as general applications such as monitoring and error reporting, are run as self-contained services. The task of deployment and operation of services is achieved by using several heterogeneous facilities, custom configuration data and scripts in several languages. In this work, we restructure the existing system into a homogeneous, scalable cloud architecture adopting a uniform paradigm, where all applications are orchestrated in a uniform environment with standardized facilities. In this new paradigm DAQ applications are organized as groups of containers and the required software is packaged into container images. Automation of all aspects of coordinating and managing containers is provided by the Kubernetes environment, where a set of physical and virtual machines is unified in a single pool of compute resources. We demonstrate that a container-based cloud architecture provides an acrossthe-board solution that can be applied for DAQ in CMS. We show strengths and advantages of running DAQ applications in a container infrastructure as compared to a traditional application model

Measurement of differential cross sections for top quark pair production using the lepton plus jets final state in proton-proton collisions at 13 TeV

National Science Foundation (U.S.

Particle-flow reconstruction and global event description with the CMS detector

The CMS apparatus was identified, a few years before the start of the LHC operation at CERN, to feature properties well suited to particle-flow (PF) reconstruction: a highly-segmented tracker, a fine-grained electromagnetic calorimeter, a hermetic hadron calorimeter, a strong magnetic field, and an excellent muon spectrometer. A fully-fledged PF reconstruction algorithm tuned to the CMS detector was therefore developed and has been consistently used in physics analyses for the first time at a hadron collider. For each collision, the comprehensive list of final-state particles identified and reconstructed by the algorithm provides a global event description that leads to unprecedented CMS performance for jet and hadronic tau decay reconstruction, missing transverse momentum determination, and electron and muon identification. This approach also allows particles from pileup interactions to be identified and enables efficient pileup mitigation methods. The data collected by CMS at a centre-of-mass energy of 8 TeV show excellent agreement with the simulation and confirm the superior PF performance at least up to an average of 20 pileup interactions

Search for heavy resonances decaying to a top quark and a bottom quark in the lepton+jets final state in proton–proton collisions at 13 TeV

info:eu-repo/semantics/publishe

Pseudorapidity and transverse momentum dependence of flow harmonics in pPb and PbPb collisions

info:eu-repo/semantics/publishe

Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV

Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio