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A System for Distributing High-Speed Synchronous High-Precision Clock and Trigger Data over Large Distances
Stockholm University, Faculty of Science, Department of Physics.
Deutsches Elektronen-Synchrotron (DESY).
Deutsches Elektronen-Synchrotron (DESY),.
Stockholm University, Faculty of Science, Department of Physics.
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2008 (English)In: Nuclear Science Symposium Conference Record, 2008. NSS '08. IEEE, 2008, 2581-2584 p.Conference paper (Refereed)
Abstract [en]

The distribution of precise timing throughout the European X-ray Free Electron Laser project [1] (XFEL) and its triggering system is a very challenging part of the system design. ADCs in data acquisition systems and DACs in control systems will require very high precision clocks. The clocks need to be synchronous to each other, both in frequency and phase, with a jitter performance better than 5 ps (RMS). At some high-speed ADCs it might even need a precision down to 0.1ps. The frequencies that must be available are the main 1.3 GHz and some frequencies below, which are all derived from the main frequency. The phase needs to be adjustable to allow synchronization between separate devices.

Place, publisher, year, edition, pages
2008. 2581-2584 p.
Keyword [en]
Clocks, Electrons, Field programmable gate arrays, Frequency synchronization, Optical fiber cables, Physics, Power cables, Telephony, Timing, X-ray lasers
National Category
Accelerator Physics and Instrumentation Control Engineering Other Electrical Engineering, Electronic Engineering, Information Engineering
Research subject
URN: urn:nbn:se:su:diva-64531DOI: 10.1109/NSSMIC.2008.4774885ISBN: 978-1-4244-2714-7OAI: diva2:458085
European XFEL
Available from: 2011-11-21 Created: 2011-11-21 Last updated: 2012-01-04Bibliographically approved
In thesis
1. FPGA-based Instrumentation for Advanced Physics Experiments
Open this publication in new window or tab >>FPGA-based Instrumentation for Advanced Physics Experiments
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Modern physical experiments often demand advanced instrumentation based on advances in  technology. This work describes four instrumentation physics projects that are based on modern, high-capacity Field-Programmable Gate Arrays, making use of their versatility, programmability, high bandwidth communication interfaces and signal processing capabilities.

In the first project, a jet-finding algorithm for the ATLAS detector at the LHC experiment at CERN was developed and implemented, and different verification methods were created to validate the functionality and reliability. The experiment uses a three level trigger system, where the first level uses custom FPGA-based hardware for analysis of collision events in real-time.

The second project was an advanced timing and triggering distribution system for the new European X-Ray Free Electron Laser (XFEL) facility at DESY in Hamburg. XFEL will enable scientists to study nano structures on the atomic scale. Its laser pulses will have the strongest peak power in the world with extremely short duration and a high repetition rate, which will even allow filming of chemical reactions. The timing system uses modern FPGAs to distribute high-speed signals over optical fibers and to deliver clocks and triggers with high accuracy.

The third project was a new data acquisition board based on high-speed ADCs combined with high-performance FPGAs, to process data from segmented Ge-detectors in real-time. The aim was to improve system performance by greatly oversampling and filtering the analog signals to achieve greater effective resolution.

Finally, an innovative solution was developed to replace an aging system used at CERN and Stockholm University to test vital electronics in the Tile Calorimeters of the ATLAS detector system. The new system is entirely based on a commercial FPGA development board, where all necessary custom communication protocols were implemented in firmware to emulate obsolete hardware.

Abstract [sv]

Inom området instrumenteringsfysik bedrivs forskning och utveckling av avancerade instrument, som används inom moderna fysikexperiment. Denna avhandling beskriver fyra projekt där programmerbara kretsar (FPGA) har nyckelfunktioner för att lösa krävande instrumenteringsuppgifter.

Den första projektet beskriver utveckling och implementering av en algoritm för detektering av partikelskurar efter partikelkollisioner i LHC-experimentets ATLAS-detektor. Experimentet genererar 40 miljoner händelser per sekund, som måste analyseras i real-tid med hjälp av snabba parallella algoritmer. Resultatet avgör vilka händelser som är tillräckligt intressanta för fortsatt noggrannare analys.

Den andra projektet beskriver utvecklingen av ett system som distribuerar klock- och trigger-signaler över ett 3 kilometers experimentområde med extrem precision, i den nya röntgenlaseracceleratorn XFEL vid DESY i Hamburg. Vid XFEL kommer man utforska nanostrukturer och till och med filma molekylers kemiska reaktioner.

I den tredje projektet beskrivs utvecklingen av ett höghastighets datainsamlingssystem, för segmenterade Ge-detektorer. Genom att översampla signalen med hög hastighet kan man uppnå en bättre noggrannhet i mätningen än vad AD-omvandlarens egna upplösning medger. Detta leder i sin tur  till förbättrade systemprestanda.

Slutligen beskrivs en innovativ lösning till ett test system för den elektronik, som Stockholms universitet har levererat till ATLAS detektorn. Det nya systemet ersätter det föregående testsystemet, som är baserad på föråldrade inte längre tillgängliga komponenter. Det nya systemet är dessutom också billigare eftersom det är baserat på ett standard FPGA utvecklingskort.

Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholm University, 2011. 99 p.
Instrumentation, Data acquisition, clock distribution, trigger, FPGA, PCB, LHC, ATLAS, XFEL
National Category
Other Physics Topics Accelerator Physics and Instrumentation
Research subject
urn:nbn:se:su:diva-64506 (URN)978-91-7447-416-9 (ISBN)
Public defence
2011-12-15, sal FD5, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 10:30 (English)
ATLAS experiment of the Large Hadron Collider experimentEuropean X-ray Free Electron Laser
Available from: 2011-11-24 Created: 2011-11-21 Last updated: 2011-12-20Bibliographically approved

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Hidvegi, AttilaBohm, Christian
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