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Level-2 Calorimeter Trigger Upgrade at CDF Laura Sartori INFN - Pisa Fermilab

This paper provides an overview of the Level-2 Calorimeter Trigger upgrade at CDF, including the limitations of the current algorithm at high luminosity and the proposed upgrade path based on new hardware and a new algorithm. The new system aims to address the challenges of surviving at high luminosity and crucial triggers, such as Higgs and Susy searches. The hardware setup and timing performance of the new system are also discussed.

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Level-2 Calorimeter Trigger Upgrade at CDF Laura Sartori INFN - Pisa Fermilab

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  1. Level-2 Calorimeter Trigger Upgrade at CDF Laura Sartori INFN - Pisa Fermilab On behalf of L2 Calorimeter Upgrade Group

  2. Overview • Description of the CDF Level-2 Calorimeter Trigger • Limitation of the actual cluster finder algorithm at High Luminosity (hardware implemented). • Upgrade path based on a new hardware and on a new algorithm (software implemented). • Description of the new system IEEE San Diego 2006

  3. CDF Data Acquisition System Crossing Rate 1.7 MHz Digitization at 132 clock cycle Detector Level 1 Trigger Synchronous 40-stages Pipeline Data latency~ 5.5 us ~ 40 kHz Level 2 Trigger Asynchronous 2-stages Pipeline Data latency~ 20 us ~ 1 kHz Level 3 Trigger Full detector readout PC farms runs reconstruction Mass Storage Accept rate <75 Hz

  4. CDF Calorimeter Trigger L2CAL Cluster Finder L2 Pulsar Crate L2 CPU L1CAL Global L2 Decision • L2 CPU takes Global decision on the base on: • Clusters calculated at L2CAL • Global Energy per event calculated at L1CAL: Missing transverse Energy (Met), Total Transverse Energy (SumET) 8-bits 10-bits Energy/Tower • Important for the surviving at High luminosity of crucial triggers: Higgs,Susy. Calorimeter IEEE San Diego 2006

  5. L2 Jet clustering at High Luminosity (I) • The algorithm forms clusters combining contiguous regions of trigger towers with non trivial energy. • At high Luminosity it causes multi-jets clusters merging (Large fake Clusters)  Ntow=70 ET=121  =18, =19 * Reconstructed Jets @ L3  Jet @ L2 IEEE San Diego 2006

  6. L2 Jet clustering at High Luminosity (II) (Jet with Energy > 40 GeV @ L2) vs Lum • Underlying Event energy increases due to pile-up interactions and possibly beam backgrounds • Towers boosted above threshold clustered together in FAKE jets: • Jet Trigger cross sections grow rapidly with luminosity • High L2 Accept Rate • Saturation of the bandwidth IEEE San Diego 2006

  7. New System Overview L2CAL L2 Pulsar Crate New Hardware Path L2 CPU NEW ALGO • Calorimeter trigger towers available in L2 CPU • Fixed Cone algorithm • Fill resolution from 10 bit based information • New Hardware Path is required • Commissioning in parasitic mode 10-bit L1CAL 10-bit Calorimeter IEEE San Diego 2006

  8. Hardware Setup Pulsar • New Path is based on: Existing Pulsar Board + new LVDS Receiver Card • PULSAR (PULSer AndRecorder) is a general purpose VME board developed at CDF to interface any user data with industrial link through the use of custom mezzanine card • CERN S-LINK (Simple LINK- 80 Mbits/sec) is the standard link to allow Pulsar to communicate with CPU via commercially S-LINK to PCI interface Card. TRIGGER TOWERS AUX card IO FPGA S-LINK : to another Pulsar or to PCI IO FPGA CTRL FPGA IEEE San Diego 2006 LVDS Mezzanine Card Receiver

  9. New L2CAL System Firmware: 1. Store data until the L1 decision arrives 2. Data merging 3. Convert data in SLINK format TIMING GOAL ~ 20 us Pulsar x9 Firmware SLINK Merger: 1. Data merging PC Pulsar x9 Pulsar Crate 1 9 slink outputs 144 cables from L1 40-bit word/cable @ CDF_clk (132 ns) 80 MhZ 32-bit @ 40 MhZ Slink merger Pulsars X6 Pulsar Crate 2 32-bit @ 40 Mhz 9 slink outputs 80 MhZ 144 cables from L1 Clustering timing ~ 10 us 80 MhZ Data transfer latency on average within ~10 us IEEE San Diego 2006

  10. Algorithm Timing Performance • CPU: Dual AMD Opteron 250/2.4GHz (L2 decision PC) • Time stamps before and after algorithm execution • Measures include MET calculation Worst Case (Max # Towers) ~ 300 typical events driving the L2 trigger Met timing vs # of input towers (Non-trivial Energy Towers) IEEE San Diego 2006

  11. Conclusions • We presented the L2 calorimeter upgrade for CDF • A New software implemented algorithm is the key • New system is very flexible and can keep up with changing luminosity conditions and can be easily optimized for new physics/higgs searches • The upgrade will grant the success of the Higgs and SUSY program • We need to develop new trigger strategy to exploit all the new design features. • The commissioning will be next spring IEEE San Diego 2006

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