Charged Particle Tracking in Real-Time Using a Full-Mesh Data Delivery Architecture and Associative Memory Techniques

We present a flexible and scalable approach to address the challenges of charged particle track reconstruction in real-time event filters (Level-1 triggers) in collider physics experiments. The method described here is based on a full-mesh architecture for data distribution and relies on the Associative Memory approach to implement a pattern recognition algorithm that quickly identifies and organizes hits associated to trajectories of particles originating from particle collisions. We describe a successful implementation of a demonstration system composed of several innovative hardware and algorithmic elements. The implementation of a full-size system relies on the assumption that an Associative Memory device with the sufficient pattern density becomes available in the future, either through a dedicated ASIC or a modern FPGA. We demonstrate excellent performance in terms of track reconstruction efficiency, purity, momentum resolution, and processing time measured with data from a simulated LHC-like tracking detector

Evaluation of an Associative Memory and FPGA-based System for the Track Trigger of the CMS-Detector

Im Jahr 2025 wird die Luminosität des Teilchenstrahls am Large Hadron Collider (LHC), dem größten Teilchenbeschleuniger der Welt mit den höchsten Energien, weiter erhöht. Dadurch werden noch mehr Teilchen gleichzeitig im Zentrum des Compact Muon Solenoid (CMS) Experimentes kollidieren. Um unter diesen neuen Bedingungen verwertbare Daten zu liefern, wird erstmals ein Spurtrigger für CMS entwickelt. Dieser verarbeitet die Daten des äußeren Spurdetektors und liefert die Parameter der Teilchenspuren an die erste Triggerstufe von CMS. Da die technischen Anforderungen an ein solches Spurtriggersystem enorm sind, wurde bisher noch nie ein Spurtrigger auf der ersten Triggerstufe eines Teilchenphysikexperimentes eingesetzt. Die Datenrate am Eingang des CMS-Spurtriggers wird beinahe 100 Tbit/s betragen und die Verarbeitungszeit darf 4 μs nicht überschreiten. Um diese außergewöhnlichen Anforderungen zu erfüllen, ist ein einzigartiges, heterogenes eingebettetes System erforderlich. Diese Dissertation präsentiert eine neu konzeptionierte Simulationsumgebung auf Systemebene für den CMS-Spurtrigger. Die Simulationsumgebung ermöglicht die Evaluation der CMS-Spurtriggerelektronik als Ganzes: von den Modulen mit den Siliziumdetektoren bis zu den Komponenten, welche die Algorithmen zur Spurerkennung ausführen. Die Simulation stellt dem Systementwickler drei Funktionen zur Verfügung: Erstens können Systemeigenschaften wie Latenz, Bandbreite und benötigte Puffergrößen abgeschätzt werden. Zweitens können verschiedene Systemarchitekturen miteinander verglichen werden. Drittens dient die Simulationsumgebung als Testumgebung für Algorithmen und Code, welcher in Field-Programmable Gate Arrays (FPGA) implementiert wird. Um realistische Ergebnisse zu erhalten, werden Daten einer Simulation des CMS-Experimentes als Eingangsdaten der Simulationsumgebung verwendet. Eines der untersuchten Konzepte für den CMS-Spurtrigger besteht aus bis zu 48 großen Baugruppenträgern mit Hunderten von Platinen. Zur Verarbeitung der Daten werden FPGAs und eigens für die Suche von Teilchenspuren entwickelte Assoziativspeicher genutzt. Prototypen einer Platine mit FPGAs und Assoziativspeicher Chips wurden am Karlsruher Institut für Technologie produziert und getestet. Zusätzlich wurde ein essenzieller Teil des CMS-Spurtriggers mithilfe der neuen Simulationsumgebung simuliert. Durch diese Implementierung wurde aufgezeigt, dass es möglich ist, ein solch großes System in der Simulationsumgebung zu simulieren. Innerhalb der Simulation werden viele Elemente des CMS-Spurttriggers vielfach instantiiert. Dabei sind die Elemente oft in regelmäßigen Strukturen wie zum Beispiel zwei- oder dreidimensionalen Rastern angeordnet. Eine SystemC-Bibliothek wurde entwickelt, um das Modellieren und Konfigurieren solcher Strukturen zu vereinfachen. Außerdem wurde eine unabhängige Kostenabschätzung des CMS-Spurtriggers durchgeführt. Diese zeigt, dass die veranschlagten 11,9 Millionen Euro ausreichen, um den auf Assoziativspeicher basierende CMS-Spurtrigger zu bauen. Werden die Werte anhand des Technologiefortschritts auf das Jahr 2022 hochgerechnet, kann sogar mit deutlich niedrigeren Kosten gerechnet werden

LHC-ATLAS実験における高速飛跡再構成システム(FTK)の構築

早大学位記番号:新7701早稲田大

Systems and algorithms for low-latency event reconsturction for upgrades of the level-1 triger of the CMS experiment at CERN

With the increasing centre-of-mass energy and luminosity of the Large Hadron Collider (LHC), the Compact Muon Experiment (CMS) is undertaking upgrades to its triggering system in order to maintain its data-taking efficiency. In 2016, the Phase-1 upgrade to the CMS Level- 1 Trigger (L1T) was commissioned which required the development of tools for validation of changes to the trigger algorithm firmware and for ongoing monitoring of the trigger system during data-taking. A Phase-2 upgrade to the CMS L1T is currently underway, in preparation for the High-Luminosity upgrade of the LHC (HL-LHC). The HL-LHC environment is expected to be particularly challenging for the CMS L1T due to the increased number of simultaneous interactions per bunch crossing, known as pileup. In order to mitigate the effect of pileup, the CMS Phase-2 Outer Tracker is being upgraded with capabilities which will allow it to provide tracks to the L1T for the first time. A key to mitigating pileup is the ability to identify the location and decay products of the signal vertex in each event. For this purpose, two conventional algorithms have been investigated, with a baseline being proposed and demonstrated in FPGA hardware. To extend and complement the baseline vertexing algorithm, Machine Learning techniques were used to evaluate how different track parameters can be included in the vertex reconstruction process. This work culminated in the creation of a deep convolutional neural network, capable of both position reconstruction and association through the intermediate storage of tracks into a z histogram where the optimal weighting of each track can be learned. The position reconstruction part of this end-to-end model was implemented and when compared to the baseline algorithm, a 30% improvement on the vertex position resolution in tt̄ events was observed.Open Acces

The ATLAS experiment at the CERN Large Hadron Collider: a description of the detector configuration for Run 3

The ATLAS detector is installed in its experimental cavern at Point 1 of the CERN Large Hadron Collider. During Run 2 of the LHC, a luminosity of ℒ = 2 × 1034 cm-2 s-1 was routinely achieved at the start of fills, twice the design luminosity. For Run 3, accelerator improvements, notably luminosity levelling, allow sustained running at an instantaneous luminosity of ℒ = 2 × 1034 cm-2 s-1, with an average of up to 60 interactions per bunch crossing. The ATLAS detector has been upgraded to recover Run 1 single-lepton trigger thresholds while operating comfortably under Run 3 sustained pileup conditions. A fourth pixel layer 3.3 cm from the beam axis was added before Run 2 to improve vertex reconstruction and b-tagging performance. New Liquid Argon Calorimeter digital trigger electronics, with corresponding upgrades to the Trigger and Data Acquisition system, take advantage of a factor of 10 finer granularity to improve triggering on electrons, photons, taus, and hadronic signatures through increased pileup rejection. The inner muon endcap wheels were replaced by New Small Wheels with Micromegas and small-strip Thin Gap Chamber detectors, providing both precision tracking and Level-1 Muon trigger functionality. Trigger coverage of the inner barrel muon layer near one endcap region was augmented with modules integrating new thin-gap resistive plate chambers and smaller-diameter drift-tube chambers. Tile Calorimeter scintillation counters were added to improve electron energy resolution and background rejection. Upgrades to Minimum Bias Trigger Scintillators and Forward Detectors improve luminosity monitoring and enable total proton-proton cross section, diffractive physics, and heavy ion measurements. These upgrades are all compatible with operation in the much harsher environment anticipated after the High-Luminosity upgrade of the LHC and are the first steps towards preparing ATLAS for the High-Luminosity upgrade of the LHC. This paper describes the Run 3 configuration of the ATLAS detector

Complexity-reduced hardware-based track-trigger for CMS upgrade

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonThe Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC) is designed to study the results of proton-proton collisions. The Tracker sub-detector is designed to detect and reconstruct the trajectories of charged particles produced by the collisions. During the lifetime of the CMS detector, there have been several upgrades aimed at increasing the chance of discovering new physics through increased luminosity levels and instrumentation of advanced technology. The High-Luminosity upgrade optimises the LHC to accelerate high-energy particles with an average of 200 proton-proton interactions per bunch crossing. The Level-1 Trigger system promptly analyses and filters collisions using hardware to reduce the data volume in real-time. For the upgrade, the trigger mechanism will use a particle trajectory estimator that discriminates between particles based on their transverse momentum (pT ). Particles with pT ≥ 2 GeV/c will be transmitted to the Level-1 Track-Trigger system for trajectory reconstruction within a fixed 3 μs latency. This thesis presents a novel Hardware-based Multivariate Linear Fitter (MVLF) system focusing on robustness in tracking efficiency and reduction in logic resource usage within the specified latency. The system components are implemented in Field Programmable Gate Arrays (FPGA), targeting 16 nm FinFET UltraScale+ silicon technology. The development was performed using the High-Level Synthesis (HLS) automation tools and the Hardware acceleration platform for Application-Specific Integrated Circuits (ASIC). A firmware demonstrator has been assembled to verify the feasibility and compatibility of the scaled system with the CMS Level-1 Track-Trigger infrastructure. The system’s performance is compared to past and current system developments, and the results are presented accordingly

High-rate irradiation of 15mm muon drift tubes and development of an ATLAS compatible readout driver for micromegas detectors

The upcoming luminosity upgrades of the LHC accelerator at CERN demand several upgrades to the detectors of the ATLAS muon spectrometer, mainly due to the proportionally increasing rate of uncorrelated background irradiation. This concerns also the "Small Wheel" tracking stations of the ATLAS muon spectrometer, where precise muon track reconstruction will no longer be assured when around 2020 the LHC luminosity is expected to reach values 2 to 5 times the design luminosity of $1 \times 10^{34} \text{cm}^{-2}\text{s}^{-1}$, and when background hit rates will exceed 10 kHz/cm$^2$. This, together with the need of an additional triggering station in this area with an angular resolution of 1 mrad, requires the construction of "New Small Wheel" detectors for a complete replacement during the long maintenance period in 2018 and 2019. As possible technology for these New Small Wheels, high-rate capable sMDT drift tubes have been investigated, based on the ATLAS 30 mm Monitored Drift Tube technology, but with a smaller diameter of 15 mm. In this work, a prototype sMDT chamber has been tested under the influence of high-rate irradiation with protons, neutrons and photons at the Munich tandem accelerator, simulating the conditions within a high luminosity LHC experiment. Tracking resolution and detection efficiency for minimum ionizing muons are presented as a function of irradiation rate. The experimental muon trigger geometry allows to distinguish between efficiency degradation due to deadtime effects and space charge in the detectors. Using modified readout electronics the analog pulse shape of the detector has been investigated for gain reduction and potential irregularities due to the high irradiation rates and ionization doses. This study shows that the sMDT detectors would fulfill all requirements for successful use in the ATLAS New Small Wheel endcap detector array, with an average spatial resolution of 140 $\mu$m and a track reconstruction efficiency of around 72\% for a single tube layer at 10 kHz/cm$^2$ irradiation rate. A second proposal for a New Small Wheel detector technology are Micromegas detectors. These highly segmented planar gaseous detectors are capable of very high rate particle tracking with single plane angular resolution or track reconstruction. The ATLAS community has decided in 2013 in favor of this technology for precision tracking in the New Small Wheels. A prototype Micromegas detector will be installed in summer 2014 on the present ATLAS Small Wheel to serve as test case of the technology and as template for the necessary changes to the ATLAS hardware and software infrastructure. To fully profit from this installation, an ATLAS compatible Read Out Driver (ROD) had to be developed, that allows to completely integrate the prototype chamber into the ATLAS data acquisition chain. This device contains state-of-the-art FPGAs and is based on the Scalable Readout System (SRS) of the RD51 collaboration. The system design, its necessary functionalities and its interfaces to other systems are presented at use of APV25 frontend chips. Several initial issues with the system have been solved during the development. The new ROD was integrated into the ATLAS Monitored Drift Tube Readout and into a VME based readout system of the LMU Cosmic Ray Facility. Additional successful operation has been proven meanwhile in several test cases within the ATLAS infrastructure. The whole data acquisition chain is ready for productive use in the ATLAS environment.Die zukuenftigen Upgrades des LHC Beschleunigers am CERN erfordern mehrere Verbesserungen der Detektoren des ATLAS Myonspektrometers, hauptsaechlich wegen der damit einhergehenden Erhoehung der unkorrellierten Untergrund Trefferrate. Dies betrifft auch das "Small Wheel" des ATLAS Endkappen-Myonspektrometers. Eine praezise Myon Spurrekonstruktion kann nicht laenger sichergestellt werden, wenn die Luminositaet gegen 2020 um einen Faktor 2 bis 5 oberhalb des Designwertes von $1 \times 10^{34} \text{cm}^{-2}\text{s}^{-1}$ liegen wird, und wegen der Untergrund Trefferraten oberhalb von 10 kHz/cm$^2$. Dies, zusammen mit dem Bedarf an einer zusaetzlichen Triggerstation mit einer Winkelaufloesung besser als 1 mrad, erfordert den Bau von "New Small Wheel" Detektoren. Der Austausch ist fuer die lange Wartungsperiode 2018 und 2019 geplant. Als moegliche Technologie fuer die beiden New Small Wheels wurden sMDT Driftrohre, basierend auf der ATLAS 30 mm Monitored Drift Tube Technologie, getestet. Bei einem halbierten Durchmesser von 15 mm erwartet man diese als genuegend hochratenfest. In der vorliegenden Arbeit wurde am Muenchner Tandembeschleuniger eine sMDT Prototypenkammer unter dem Einfluss von Protonen-, Neutronen- und Photonenbestrahlung bei hohen Raten getestet, und somit die Bedingungen fuer ein LHC Hochluminositaetsexperiment nachgestellt. Spuraufloesung und Rekonstruktionseffizienz fuer minimalionisierende Myonen werden als Funktion der Bestrahlungsrate praesentiert. Die Geometrie der Myonentrigger im Experiment erlaubt es, zwischen Effizienzverlusten aufgrund von elektronischen Totzeiteffekten und Raumladungseffekten zu unterscheiden. Mittels modifizierter Ausleseelektonik wurde die analoge Pulsform der Detektoren im Hinblick auf eine Abnahme der Gasverstaerkung und potentielle Unregelmaessigkeiten aufgrund der hohen Bestrahlungsraten und -staerken untersucht. Das Ergebnis der Studie zeigt, dass die sMDT Detektortechnologie die hohen Anforderungen an die New Small Wheel Detektoren erfuellt. Bei einer Bestrahlungsrate von 10 kHz/cm$^2$ liegt die mittlere Einzelrohr-Ortsaufl\"osung bei 140 $\mu$m und die Spurrekonstruktionseffizienz bei etwa 72\% pro Rohrlage. Als weitere Technologie fuer die New Small Wheels wurden Micromegas Detektoren vorgeschlagen. Diese mikrostrukturierten planaren Gasdetektoren mit hoher Ortsaufloesung sind konstruktionsbedingt hochratenfest und erlauben zusaetzlich Winkelaufloesung und Spurrekonstruktion in einer einzelnen Detektorlage. 2013 hat sich die ATLAS Kollaboration fuer diese Technologie als Praezisions-Spurdetektoren in den New Small Wheels entschieden. Ein Prototyp Micromegas Detektor wird im Sommer 2014 auf einem der beiden ATLAS Small Wheels installiert als Technologietest und Probedurchlauf der noetigen Aenderungen an ATLAS Hard- und Software. Hierfuer ist ein ATLAS-kompatibler Read Out Driver (ROD) entwickelt worden, der es erlaubt, die Prototypkammer vollstaendig in die ATLAS Datenaufnahme zu integrieren, um somit den Erkenntnissgewinn aus der Installation zu maximieren. Die Hardware dieser Ausleseelektronik basiert auf modernsten FPGAs und wurde im Rahmen der RD51-Kollaboration als Scalable Readout System entworfen. Das Firmwaredesign, seine Funktionalitaet und die Verbindungsglieder zwischen den verschiedenen Komponenten der Auslesekette werden unter Verwendung von APV25 Auslesekarten vorgestellt. Alle anfaenglichen Probleme des Systems wurden im Rahmen dieser Arbeit behoben. Das System wurde erfolgreich in die Auslesekette des LMU Hoehenstrahl Messstandes integriert und somit sowohl mit der Ausleseelektronik der ATLAS Monitored Drift Tubes, als auch einer VME-basierten Datenaufnahme synchronisiert. Innerhalb der ATLAS Datenaufnahmekette wurden \mbox{zwischenzeitlich} weitere erfolgreiche Integrationstests durchgefuehrt. Als Ergebnis ist das Systems bereit, um innerhalb des ATLAS Detektors problemlos eingesetzt zu werden

Study and Optimization of Particle Track Detection via Hough Transform Hardware Implementation for the ATLAS Phase-II Trigger Upgrade

In the CERN of Geneva the Large Hadron Collider (LHC) will undergo several deep upgrades in the next years. Instantaneous and Integrated Luminosity will be increased respectively up to 5−7·10 34 cm −2 s −1 and 3000 f b −1 . Alongside this collider the experiments exploiting LHC will undergo through upgrades crucial to fulfill the HEP goals. The ATLAS upgrades are divided into phases, namely Phase-I and Phase-II. Part of the ATLAS upgrade concerns the Trigger and Data Acquisition systems. In particular, for the ATLAS trigger, a big technological update is planned for the Phase-II. My contribution to these Phase-I and Phase-II plans has been focused to the Trigger and Data Acquisition system electronic update. In the Phase-I upgrade I worked at the commissioning of the new FELIX readout cards FLX-712 which will be mounted on part of the TDAQ system. These cards are FPGA based with a bandwidth up to 480 Gb/s and exploit PCI Express Generation 3 technology. My work has been focused on the preparation and the follow up of part of the tests of the cards for quality checks and controls. The ATLAS Phase-II trigger targets to increase its output data stream to the Tier 0 of one order of magnitude. For the ATLAS Phase-II upgrade I developed an implementation of a tracking algorithm to fulfill the new trigger requirements. This algorithm, known as Hough Transform, is used to track particle trajectories and it has been already demonstrated to be suited for the ATLAS specifications. In this thesis I present the study, the simulations and the hardware implementation of a preliminary version of the Hough Transform algorithm on a XILINX Ultrascale+ FPGA device

R&D on the Resistive Plate Chamber for the Phase-II Upgrade of the CMS Muon Detector

The Doctoral Thesis subject has been proposed by the CMS RPC Collaboration to demonstrate that iRPC technology is the most suitable choice for the upgrade of the Muon System. The next research activities have been conducted in this context: The first activity, conducted in the framework of the iRPC RE3/1 and RE4/1 chambers integration and installation in the innermost region of CMS Muon Spectrometer, is focused on survey measurements performed in order to determine the space actually available for future installations during the Yearly Technical Stops at the end of 2022 and 2023. Surface topology and geometry of the Yoke Endcap (YE) ±2 and YE±3 iron disks in the region 1.8<|eta|<2.4 have been studied in detail by using different methods such as photography, photogrammetry, theodolite and infrared proximity sensor. After analyzing the experimental data obtained during the survey measurements, I developed the very precise 3D-model of the mechanical simulation for the installation of the RE3/1 and RE4/1 detectors in the dedicated |eta| region. I designed the mechanical components to mount chambers here. These results of my work were reported in the CMS Muon Technical Design Report (TDR) which was submitted to the CMS Muon Committee on 12 September 2017. The second activity has been focused on the developing, commissioning and characterization of the iRPC RE3/1 and RE4/1 detector prototypes. By using the information obtained during the previous activity, in August 2017 at the CERN CMS-RPC QA/QC facility, I organized the development and assembly of the first two real-size RE3/1 and RE4/1 detector prototypes and studied their detection performance with the new version of the PETIROC ASIC Front-end electronics. I was the key person who participated in all production processes on the construction and testing the detecting elements, assembling of the new prototypes and subsequent testing them with the new electronics under muon beam at the CERN Gamma Irradiation Facility (GIF++) in August 2018. By using the unique test area of the CERN GIF++ facility, I studied the iRPC detector performances at the different background conditions which will be similar to the future CMS conditions during the HL-LHC program. By studying the rate capability of the real-size iRPC detector prototypes I have experimentally shown that the new iRPC technology can effectively operate in the harsh background CMS environmental and can fulfill all physics requirements of the CMS experiment. The third my activity included the testing of the new INFN Rome Front-end electronics together with iRPC detector prototype. The INFN Rome electronics has been proposed as a possible alternative to PETIROC ASIC electronics in time for the CMS-RPC system upgrade project, thus increasing the chance of success for the project. This has been the main strategy adopted by the CMS-RPC community and, consequently, it was necessary to find another available technology in order to develop the Front-end electronics to readout the iRPC detectors. In September 2018, I developed and assembled the second real-size iRPC RE4/1 detector prototype in the INFN Rome Tor Vergata laboratories (Italy) in order to study the performance with the INFN Rome Front-end boards. As in the previous research activity, I organized the subsequent testing of the iRPC detector prototype with the new electronics in the last available muon particle beam in the GIF++ facility at CERN before the starting of the Long Shutdown -2 period at LHC. In order to compare the results obtained from the first two RE3/1 and RE4/1 detector prototypes, I have studied the same number of chamber parameters of second iRPC RE4/1 detector prototype, such as a detection efficiency, cluster size, and rate capability. I experimental shown that this type of new Front-end board can be a great substitute for the PETIROC ASIC electronics. A majority of the results obtained during the last two years of Ph.D. contributed to the success of the iRPC project and its final approval by CMS Collaboration