# Presentation: 436819

## Physics Priorities for Trigger Development 

**Leonard Apanasevich (UIC)**
**Pedrame Bargessa (Rice)**

- Leonard Apanasevich (UIC)  Pedrame Bargassa (Rice)

- CMS Week Sept '07

## 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

- Leonard Apanasevich (UIC)  Pedrame Bargassa (Rice)

- CMS Week Sept '07

## Trigger Development Group (i)

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

- Ensure the resultant global menu fits within the
- constraints 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:

- Leonard Apanasevich (UIC)  Pedrame Bargassa (Rice)

- CMS Week Sept '07

## 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

**Immediate priority**

- Leonard Apanasevich (UIC)  Pedrame Bargassa (Rice)

- CMS Week Sept '07

## 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

- Leonard Apanasevich (UIC)  Pedrame Bargassa (Rice)

- CMS Week Sept '07

## 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**

- Leonard Apanasevich (UIC)  Pedrame Bargassa (Rice)

- CMS Week Sept '07

## Simulated L1 rates at 1028

- Leonard Apanasevich (UIC)  Pedrame Bargassa (Rice)

- CMS Week Sept '07

## 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**

- Leonard Apanasevich (UIC)  Pedrame Bargassa (Rice)

- CMS Week Sept '07

## 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

- Leonard Apanasevich (UIC)  Pedrame Bargassa (Rice)

- CMS Week Sept '07

## 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:

- Leonard Apanasevich (UIC)  Pedrame Bargassa (Rice)

- CMS Week Sept '07

## 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

- Leonard Apanasevich (UIC)  Pedrame Bargassa (Rice)

- CMS Week Sept '07