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New Trigger Possibilities

New Trigger Possibilities. Peter-Bernd Otte – Sep. 2009 CB collaboration meeting, Edinburgh. A new Trigger for our experiments. All modern experiments rely on FPGA triggers GSI, ATLAS, CMS, ... Our FPGA Møller trigger works reliable New trigger for our entire experiment:

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New Trigger Possibilities

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  1. New Trigger Possibilities Peter-Bernd Otte – Sep. 2009 CB collaboration meeting, Edinburgh

  2. A new Trigger for our experiments • All modern experiments rely on FPGA triggers • GSI, ATLAS, CMS, ... • Our FPGA Møller trigger works reliable • New trigger for our entire experiment: • works in parallel to the existing trigger • ability to map the existing trigger logic • can perform far much more advanced triggering • But: What is an FPGA? • semiconductor device, great capabilities

  3. What is an FPGA? (1/3) • Think of: building trigger electronics • take CAMAC/NIM logic modules (AND/OR) • set it up: • using cables • program modules • So far so good: • What if it becomes more complex?

  4. What is an FPGA? (2/3) • More sophisticated trigger electronics: input output Scale: meters Scale: mm

  5. Field-programmable gate array (FPGA) (3/3) logiccell („modules“): • Can act as: logic, scaler, TDC, … • is smaller, faster, needs less power, cheaper Interconnection (“cables”): input output • Comparison: FPGA... • “has” 1000’s of modules and cables • ~300 I/O signals • configuration via software(behaviour of cells and interconnection) clock programmableswitches

  6. New trigger hardware • New electronic cards already ordered • „VUPROM 2“ from GSI • also used @GSI and KAOS@A1 • FPGA: „Virtex 4“ from Xilinx, 400 MHz • 224 inputs, 32 outputs, LVDS • 6U form factor • VMEbus connectivity • cheap: 2k€ apiece • 10 cards ordered

  7. Connected detectors • With new hardware: Possible to include all detectors • All CB crystals (672x  720 cable pairs) • All PID stripes (24x) • Inner TAPS crystals (72x) • Tagger channels (352x) • Endpoint Tagger (~64x) • TOF-Panels • Energy sum • Feasibility unknown: • Remaining TAPS crystals and vetos • Request to responsible experimentalists! S=1232x

  8. Cluster Counter Algorithm • Algorithm steps • Load hit pattern • Shrink clusters(using set of rules) • Count number of cells= number of clusters • If desired cluster count  trigger! • “cellular automata logic” (each crystal = cell) crystal scheme of CB •  more details: (coffee break)

  9. Cluster Counter test (1/2) • during July run • 128 crystals used for test (~ 20% of CB)

  10. Cluster Counter test (2/2) • Required time only ~140ns • Sample results for cluster count = 3 • Works reliably, next: whole CB & more • Check: efficiency, purity, simulation • essential for each new trigger algorithm (a) (b) (c)

  11. Trigger electronics: Outlook • Enough inputs: • feasible to include signals from all detectors • New trigger electronics will be installed • in parallel to existing • Request to experimentalists: • Allocate digital signals from different apparati • New trigger algorithms • Grant: • strike up a discussion during coffee break (coffee break)

  12. Thankyouforyourattention

  13. Appendix For the coffee break: Peculiarities of FPGA? New trigger compounds Cellular Cluster Counter Algorithm in greater detail

  14. Field-programmable gate array

  15. Field-programmable gate array (FPGA) (1/2) • Semiconductor device that can be configured via software • Architecture: • logic blocks (~106) (LUTs, adder, etc.) • routing matrix • I/O pads

  16. Field-programmable gate array (FPGA) (2/2) • Important difference:Concurrent processing ⇔ unlike microprocessors • Example: microprocessor FPGA (electronics) Input u, vandw sequential Output z

  17. New trigger compounds (what is possible) Comparison to old trigger

  18. Actual Trigger possibilities • Included detectors: • Crystal Ball, TAPS, PID • Triggering on: • cluster count (simple logic) • energy sum (in CB only) • charged particles involved (PID-OR) • Disadvantages: • cluster count only a rough estimate • no complex conditions • (e.g. “planar 2 body hit, one uncharged”) • hard to apply changes • not all detectors included • some trigger relevant signals not recorded New Trigger can remove all disadvant.

  19. What can the new trigger achieve? • Planned so far: • Improved cluster counter(cellular automata logic) • Cluster counter for charged/uncharged particles • Detect planar events • Møller trigger • Include: • CB crystals, PID, inner TAPS and Tagger

  20. Interesting facts / Outlook • Is it possible to trigger on TAPS? • Inner rings  standard electronics  Yes. • Rest of TAPS  T. Rostomyan building analog splitter • More digital signals welcome: • Č, TOF, endpoint tagger, test paddles, etc.

  21. Unveil new possibilities • Possible (new) trigger compounds: • time (signal duration & distance) • handle EACH input channel differently • certain input pattern (AND, OR, …) • certain sequence of signals (1st … then …) • record intermediate trigger steps with data • Limit: space on FPGA (number of logic cells)

  22. Cellular Cluster Counter Algorithm

  23. Cluster Counter Algorithm (1/4) • Cellular automata, basic declarations: • Each crystal in CB is represented as a “cell” • Each cell: • has a status (marked/unmarked) • knows status of 10 neighbours: • can only toggle its own status

  24. Cluster Counter Algorithm (2/4) • Algorithm steps • Load hit pattern into cells • Apply “replacement rules”, until no more changes occur ( see next slide) • Count number of marked cells = number of clusters • If desired number of clusters  trigger

  25. Cluster Counter Algorithm (3/4) • 15 replacement rules • Leave cluster number constant • No overlap between rules • Relevant neighbours vary • Colour code: Not for up/down cells at the same time + their rotated versions

  26. Cluster Counter Algorithm (4/4) • Problem: Stops, if holes are bigger than 1 crystal • Fortunately not critical: happens only ~once a day

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