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Cutting-Edge L1CaloTrigger Algorithms for High-Energy Physics Research

Explore detailed L1CaloTrigger algorithms by Sridhara Dasu at the University of Wisconsin, including Good Jets and HT triggers, LUT definitions, and GT algorithm updates for CMS research studies at 2 x 10^33 cm^-2 s^-1. Learn how to optimize trigger efficiency and implement topological cuts for better performance.

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Cutting-Edge L1CaloTrigger Algorithms for High-Energy Physics Research

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  1. L1CaloTrigger Algorithms • Sridhara Dasu • University of Wisconsin • Algorithms: Details, Updates and Simulation • 2 x 1033 cm-2 s-1 studies (CMS IN 2002/19) • Highlights • Good jets and HT • What will be implemented in GCT/GT • Unexplored features - invitation to participate • Define LUTs etc. in RCT, GCT • Define GT algorithms Sridhara Dasu

  2. Overview GCT BU/PU RCT TPG GT Sridhara Dasu

  3. Calorimeter Geometry EB, EE, HB, HE map to 18 RCT crates Provide e/g and jet, t, ET triggers Sridhara Dasu

  4. Trigger Mapping Sridhara Dasu

  5. Electron/Photon Algorithm Sridhara Dasu

  6. t / Jet Algorithm Sridhara Dasu

  7. 8-bit nonlinear EM ET 7-bit linear ET Lookup table for arbitrary nonlinear transform - including making E+H and H/E Electron 1-bit EM fine-grain bit 1-bit H/E, FG Veto 9-bit linear ET 8-bit nonlinear HD ET Jet / t 1-bit Activity Tower Level Memory LUT • Fully programmable LUT, Current default values: • Electron scale: 0.5 GeV LSB, Emax=63.5 GeV • Veto: OR of fine-grain veto and H / E < 5% • Jet / t scale (E+H): 1.0 GeV LSB, Emax=511 GeV • Jet energy (12x12 tower sum), Emax=1 TeV • Activity level for t pattern: E > 2 GeV, H > 4 GeV Sridhara Dasu

  8. ET18 ET1 ET2 Ex1 Ex2 Ex18 Ey1 Ey2 Ey18 Missing / Total ET Algorithm 360o LUT Strip ET sum over all h For sums ET scale LSB (quantization) ~ 1 GeV is used Df = 20o used instead of HCAL tower size: Df = 5o f …… 40o 20o 0o -5 ET 5 0 h MET Sridhara Dasu

  9. Trigger Rates Vs Threshold Sridhara Dasu

  10. Trigger Efficiency Turn-on Sridhara Dasu

  11. Cal Trigger Rates: 2 x 1033 cm-2 s-1 Selected Scenario: 5 kHz e/g, 5 kHz t,jets, 1 kHz combined, rest m Sridhara Dasu

  12. Physics Efficiency: 2 x 1033 cm-2 s-1 Scenario: 5 kHz e/g, 5 kHz t,jets, 1 kHz comb, rest m No generator level cuts other than requiring trigger objects within calo. (h<5) or tracker (e,g,t) acceptance Sridhara Dasu

  13. Good Jets • L1CaloTrigger finds jets of three types • Central, Forward and t jets • We send GT 4 objects of each type • These are mutually exclusive lists • For pure jet triggers, we need to use objects from all three categories, i.e., combine and re-sort • Although, this is easy to implement in software, we will use too many GT algorithm slots • Use good jet (ET>Threshold) counts • Can count within programmable h cuts • Several counts available • For example: 2 jets in central, 1 in +forward, 1 in -forward • Need simulation studies to define what is useful Sridhara Dasu

  14. HT Trigger • Total scalar ET integrates too much noise and is not easily calibrated • At L1 tower-by-tower ET calibration is not available • However, jet calibration is available as f(ET, h, f) • Therefore, HT which is the sum of scalar ET of all high ET objects in the event is more useful for heavy particle discovery/study • SUSY sparticles • Top • GCT should be able to implement it (FPGAs + flexible backplane) • Use top 8 or 12 candidates in sorted good jet list • Sum ET of good jets with ET>threshold (e.g., 10 GeV) Sridhara Dasu

  15. GCT/GT Algorithm Agreement • HT from GCT to GT on separate cable in same format as ET • Study jet counts with an eye towards increasing numbers and categories • Works on good* jets (ET cut) • *Should include all 3 categories (C + F + ) • Decide by June CMS Trigger Meeting • Jets are calibrated with LUTs • Keep 4 x (C + F + ) = 12 Jet List to GT Sridhara Dasu

  16. Summary • RCT preproduction prototypes implementing the algorithms and programmability as described in this talk are built • The default values for LUTs coded in ORCA perform quite well for discovery physics • Need to further optimize the use of L1 LUTs • GCT will implement good jet counts with cuts on various h and f regions, and HT trigger • Need to explore the use of the jet counts for use in multi-jet physics events • Will help save some GT algorithms • Topological trigger cuts in GT • Jim Brooke started exploring Dh cut for WW fusion • L1 group will be happy to help anyone interested in optimization of cuts to improve trigger performance. Sridhara Dasu

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