1. April 10 2008CMS Trigger Upgrade Workshop - Paris1 Christian Bohm, Stockholm University for the L1 calorimeter collaboration The ATLAS Trigger Upgrade n The ATLAS L1 calo upgrade discussions are still in an early stage n We had a first dedicated upgrade meeting in January n We are now in the process of formulating an EoI n Aiming at a R&D proposal late this year

2. April 10 2008CMS Trigger Upgrade Workshop - Paris2 The present L1 calo trigger is now operational n Few details remain n Much effort has gone into the production, installation and commissioning n Much work with cabling n Up to now the emphasis has been on the initial system operational n Upgrade work only started recently

3. April 10 2008CMS Trigger Upgrade Workshop - Paris3 ATLAS TDAQ Overview CALOMUONTRACKING Pipeline memories Derandomizers Readout drivers (RODs) Full event buffers and processor sub-farms Event builders Level 1 trigger Level 2 trigger Event filter Region of interest CTP calo muon Data recording

4. April 10 2008CMS Trigger Upgrade Workshop - Paris4 The upgrade plans are driven by n Physics - need for a non-trivial increase of the L1 trigger rejection rate with about a factor of 10, since the L1 accept rate can not be easily increased. n Technology - the availability of higher performance components such as larger and faster FPGAs, higher bandwidth transmission links and new backplane technologies n Machine parameters – bunch crossing rate, luminosity, … n Costs n Subdetector plans: possibility of full readout of all calorimeter data, track trigger, etc. n Experience from present trigger construction

5. April 10 2008CMS Trigger Upgrade Workshop - Paris5 Increasing the rejection rate n For a non-trivial increase of the rejection rate we need more information such as: n higher granularity and depth segmented ECAL data, n depth segmented HCAL data, n tracker information n We probably need topological trigger algorithms n We need a larger parameter space for the central TP – more threshold levels etc. n And we may get: n Digital input data extracted from the DAQ stream possibly with n Higher resolution n But first and foremost we need SIMULATIONS to guide our decisions

6. April 10 2008CMS Trigger Upgrade Workshop - Paris6 Changing design parameters The calorimeter sample rate will probably stay the same which has a major impact on the design – the bunch crossing rate less so. Longer latency allowing more complex algorithms – one  s in the L1 trigger doubles the available processing time If full readout of all calorimeter data is chosen it requires high capacity trigger preprocessors probably near the Read-Out Drivers producing data streams to the L1 trigger and to the L2 and DAQ Large # high capacity links needed – The GTB is one promising candidate for RO and DC but other alternatives exist

7. April 10 2008CMS Trigger Upgrade Workshop - Paris7 Possible future ATLAS TDAQ Overview CALOMUONTRACKING Level 1 preprocessors Readout drivers (RODs) Full event buffers and processor sub-farms Event builders Level 1 trigger Level 2 trigger Event filter Level 1.5 trigger CTP calo muon Data recording Pipeline memories

8. April 10 2008CMS Trigger Upgrade Workshop - Paris8 Technology considerations 1 Decision to switch from ASICS to FPGAs has allowed many short and late design cycles - try to avoid unnecessary ASICs in SLHC L1 trigger as well The use of multi purpose components (boards and backplanes) has proven successful - will be a guiding principle in the SLHC design The higher FPGA complexity and higher clock rates will allow greater flexibility in choice of algorithms – but, this flexibility will be constrained by the chosen connectivity If it is decided to bring all calo data to the counting room a huge total bandwidth is required – a large # of fast fiber links – present design 7klinks @400Mb/s, new design with full readout needs ~40klinks@4Gb/s

9. April 10 2008CMS Trigger Upgrade Workshop - Paris9 Technology considerations 2 FPGAs SERDES allow ~ 6Gb/s but there are telecom components that deliver higher performance Wavelength multiplexing techniques can greatly reduce # fibers – simplifies cabling Clock distribution ´between modules a challenge – GBT one possibility Many combinations to investigate

10. April 10 2008CMS Trigger Upgrade Workshop - Paris10 Logistics issues Managing and sharing firmware designs between developers and institutes Early development of complicated algorithms for future hardware Evaluating new firmware design tools

11. April 10 2008CMS Trigger Upgrade Workshop - Paris11 Different Scenarios Do nothing Must be verified that present system is not adequate at SLHC Small scale changes Similar architecture but with digital transmission Larger changes Increased granularity depth segmentation Radical redesigns New trigger sources – e.g. track trigger

12. April 10 2008CMS Trigger Upgrade Workshop - Paris12 Possible R&D program Stage 1 – generic – low cost and short time scale Evaluate new FADC front end processing Faster generic processor module with current architecture Small link technology test boards Algorithm analysis for high granularity data Stage 2 – specific – higher costs and longer time scale Build demonstrator system in new technology crate environment Develop interface with calorimeter preprocessor

13. April 10 2008CMS Trigger Upgrade Workshop - Paris13 SLHC L1 collaborators From the L1 calo trigger: University of Birmingham, UKContact: Dave Charlton University of Heidelberg, GermanyContact: Karlheinz Meier University of Mainz, Germany Contact: Stephan Tapprogge Queen Mary, University of London, UKContact: Eric Eisenhandler Stockholm UniversityContact: Christian Bohm Rutherford Appleton Laboratory, UKContact: Norman Gee New groups: Michigan State University, USAContact: Maris Abolins Argonne National Laboratory, USAContact: Bob Blair

14. April 10 2008CMS Trigger Upgrade Workshop - Paris14 SLHC Development projects Multi-Gigabit links, Timing Distribution, Algorithm Firmware (Stockholm) Clock Jitter reduction, JEM emulation, Offline simulation (Mainz) High-speed design technologies, Algorithms, Architecture, Offline Simulation (Birmingham, QMUL, RAL) Digitization and signal processing technologies (Heidelberg) General purpose trigger evaluation board ( Michigan)

15. April 10 2008CMS Trigger Upgrade Workshop - Paris15 Conclusions A large design phase space but many constraints Close collaboration with calorimeters needed Regular ATLAS – CMS trigger discussion may be useful (RD27)