CMS Week Sept '07Leonard Apanasevich (UIC) Pedrame Bargassa (Rice) 1 Physics Priorities for Trigger Development Leonard Apanasevich (UIC) Pedrame Bargessa

CMS Week Sept '07 Leonard Apanasevich (UIC) Pedrame Bargassa (Rice)

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Physics Priorities for Trigger Development

Leonard Apanasevich (UIC)Pedrame Bargessa (Rice)


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Outline

• Introduction to the Trigger Development Group

• Physics priorities during the initial commissioning stage

• Initial trigger menu planning• Start-up Min-Bias Trigger Suite• Evolution of the Trigger Menu


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Trigger Development Group (i)

Rates &

Chi-Nahn

Ngyuen

Menu Compile & Eval.

Alessio Ghezzi

Simone Gennai

PerformanceMetrics

Silvia Lopez

PAG Contacts

Trigger Menu DevelopmentLeonard Apanasevich

Pedram Bargassa

Prescales

Ideas for new triggers come in from PAG’s,POG’s, DPG’s, trigger community.

Ensure the resultant global menu fits within theconstraints of the L1 and HLT systems.If necessary fine tune thresholds and prescales

Provide the tools and expertise to incorporate new trigger paths in the menu

Evaluate efficiencies and CPU performance for various luminosity and pileup scenarios

For each new trigger:


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Trigger Development Group (ii)

• Provide trigger menus for luminosity/pileup scenarios envisioned during the initial startup stage of the LHC

• Develop infrastructure needed to allow flexible and rapid development of trigger menus while simultaneously keeping an eye on:– Rates, Efficiencies, and CPU

performance

Rates &

Chi-Nahn

Ngyuen

Menu Compile & Eval.

Alessio Ghezzi

Simone Gennai

PerformanceMetrics

Silvia Lopez

PAG Contacts

Trigger Menu DevelopmentLeonard Apanasevich

Pedram Bargassa

Prescales

Immediate priority


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Physics Priorities for Phase A

• Calibrate and align the detector; understand the trigger system– Minbias PT and Rapidity Distributions

– Jet, J/Ψ, Υ, etc. triggers– Establish MET– Gamma + Jet Calibration

• Begin to re-establish the Standard Model– Study Jet Angular Distribution, Dijets– Look at standard candles: W, Z, top


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LHC Startup Stages

Bunches * Ib Luminosity Event rate

1 x 1 18 1010 1027 Low

43 x 43 18 3 x 1010 3.8 x 1029 0.05

43 x 43 4 3 x 1010 1.7 x 1030 0.21

43 x 43 2 4 x 1010 6.1 x 1030 0.76

156 x 156 4 4 x 1010 1.1 x 1031 0.38

156 x 156 4 9 x 1010 5.6 x1031 1.9

156 x 156 2 9 x 1010 1.1 x1032 3.9

Mike Lamont, 20.06.07:

Stage A Summary


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Simulated L1 rates at 1028

•No thresholds other than noise suppression needed at L = 1028-1029 for all triggers: muons, e/, jets, missing ET, HT

Plot made using 10 million minbias events - no pileup

(from S. Dasu)


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Initial Trigger Menu

• Need HLT early on to reduce Level-1 output rate to ~ 200 Hz to tape

Suite of min-bias triggers Calorimeter low ET or any muon (no PT cut) Calorimeter low ET Electron ( 5 GeV) or Jet

( 10 GeV) Any muon (effectively 3 GeV PT cut) Other candidate triggers for later running are

active for diagnostic and study purposes

Level-1 Trigger Totally Open @ 12.5 kHz


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MinBias Trigger Suite

• Prescaled events in crossings and gaps• Minimum total calorimeter Etmin > Enoise

• Single-tower triggers • Low threshold L1 "jet" trigger (~10 GeV Et)

– Separate forward jets threshold for HF trigger as well (Etmin(HF) > Enoise)

• Low threshold Electron trigger (no isolation requirements) • HF ET rings (calculated in GCT from RCT sums).• Tower over threshold bits in HB/HE/HF • Total ET seen in the detector -- this is part of the regular trigger• Low threshold Jet trigger – also part of the regular trigger• Dedicated scintillators in the forward region (aka OPAL

scintillators) -- limited acceptance but used as a check• TOTEM detectors if available


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Evolution of the Trigger Menu

• Keep low threshold triggers by adding conditions and/or prescales– Electrons: add isolation at lower thresholds, H/E– Jets: change prescales/add -bits to preserve thresholds for ’s.– Muons: add quality conditions at lower thresholds

• more hits on muon tracks of individual muon trigger systems• require coincidence between RPC and either DT or CSC• add isolation at lower thresholds

• Raise thresholds for “unrestricted” triggers– Above lowest possible thresholds do not impose conditions– Calorimeter: no isolation above higher threshold or -bits– Muon: remove coincidence & isolation, relax hit requirement

• L1 conditions first validated in HLT, then migrated

Employ simultaneous strategies as luminosity & rates rise:


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Conclusions

• The Trigger Development Group has been formed and is working on preparing trigger menus for the initial commissioning stage of the LHC

• Strategies for trigger development and evolution have be implemented

• We request input from all corners of the collaboration

• We are looking forward to the challenges that lie ahead in the upcoming months

Documents

CMS Week Sept '07Leonard Apanasevich (UIC) Pedrame Bargassa (Rice) 1 Physics Priorities for Trigger Development Leonard Apanasevich (UIC) Pedrame Bargessa