# Presentation: 476616

## Basic Trigger Rates

- December 3, 2004

## References

- Physics and Detector Performance TDR
- _[http://www.cern.ch/Atlas/GROUPS/PHYSICS/TDR/physics_tdr/printout/Volume_I.pdf](http://www.cern.ch/Atlas/GROUPS/PHYSICS/TDR/physics_tdr/printout/Volume_I.pdf)_
- _[http://www.cern.ch/Atlas/GROUPS/PHYSICS/TDR/physics_tdr/printout/Volume_II.pdf](http://www.cern.ch/Atlas/GROUPS/PHYSICS/TDR/physics_tdr/printout/Volume_II.pdf)_
- High Level Trigger.... TDR
- _[http://atlas-proj-hltdaqdcs-tdr.web.cern.ch/atlas-proj-hltdaqdcs-tdr/](http://atlas-proj-hltdaqdcs-tdr.web.cern.ch/atlas-proj-hltdaqdcs-tdr/)_
- Level 1 Trigger TDR
- _[http://atlasinfo.cern.ch/Atlas/GROUPS/DAQTRIG/TDR/V1REV1/L1TDR_all.pdf](http://atlasinfo.cern.ch/Atlas/GROUPS/DAQTRIG/TDR/V1REV1/L1TDR_all.pdf)_
- Comparison of ATLAS and CMS Trigger Rates
- http://agenda.cern.ch/askArchive.php?base=agenda&categ=a01941&id=a01941s22t3/transparencies
- High Level Trigger...LHCC Review June 2004
- http://agenda.cern.ch/askArchive.php?base=agenda&categ=a041899&id=a041899s1t7%2Ftransparencies%2Fhlt_final.ppt
- ATLAS Trigger Menus for the LHC Start-up Phase
- http://doc.cern.ch//archive/electronic/cern/others/atlnot/Note/daq/daq-2003-004.pdf
- From the ancient days...Supercollider Physics, EHLQ, Reviews of Modern Physics, Vol. 56, No. 4, October 1984

## Goal

- Introduction
- Nomenclature
- Basic rates
- Electrons
- Muons
- Jets
- Etc

## Very Rough Idea of Rates

- Old plot
- Remember there are uncertainties in the cross sections
- I have not been able to find a recent compilation of relevant cross section predictions...this would be useful to have
- Apologies for quality of some graphs...

## From Physics TDR

## Trigger Concept and Definition

## High Level Trigger(HLT)

***Level2***

**HLT Data Flow Software**

**HLT Selection Software**
***Framework ATHENA/GAUDI***
***Reuse offline components***
***Common to Level-2 and EF***

**Offline algorithms used in EF**

- Trigger Selection Example

- LVL1 muon

- LVL2 calo isol

- LVL2 tracking

- EF muon

- LVL2 muon

- Muon

- EF calo isol

- EF tracking

## HLT Trigger Objects

| Selection | 2x1033 cm-2s-1 | Rates (Hz) |
| --- | --- | --- |
| Electron | e25i,  2e15i |  ~40  |
| Photon | 60i,  220i |  ~40 |
| Muon | 20i,  210 |  ~40 |
| Jets | j400, 3j165, 4j110 |  ~25 |
| Jet & ETmiss | j70 + xE70 |  ~20 |
| tau & ETmiss | 35 + xE45 |   ~5 |
| b-physics | 26 with mB /mJ/ |  ~10 |
| Others | pre-scales, calibration, ... |  ~20 |
| Total |  | ~200 |

- Wont talk about these

- Note 2x1033 is the nominal max luminosity for the initial running...optimistic

## HLT Nomenclature

- From the HLT TDR, section 4.4
- In the subsequent sections, the use of labels with the form ‘NoXXi’ to identify specific trigger
- items will be used. The meaning of the labels is the following:
- ‘o’ indicates the type of the selection
- (‘e’ for electron, ‘γ’ for photon, ‘μ’ for muon, ‘τ’ for a τ hadron, ‘j’ for jet, ‘b’ for a b-tagged
- jet, ‘xE’ for missing transverse energy, ‘E’ for total transverse energy and ‘jE’ for the total transverse energy obtained using only jets);
- ‘XX’ gives the threshold in transverse energy (in units of GeV);
- ‘N’ the number of objects;
- and ‘i’ indicates an isolation requirement.
- As an example, 2μ20i refers to the requirement of two muons, with a pT threshold of 20 GeV each, fulfilling isolation criteria. The thresholds indicate the true value above which the selection has good efficiency.
- The exact value for the efficiency obtained depends on the implementation of the algorithm and
- the details of the criteria applied.
- Note that there is a different, but similar, nomenclature for the LVL1 trigger objects.

## Efficiency Example

## Single Electrons/Photons LVL1

- The rate of the LVL1 electron/photon triggers is dominated by misidentified jets.

- The *E*T-threshold scale in the plot is defined so that the efficiency for selecting genuine electrons with transverse energy equal to the quoted value is 95%.

## Electron/photon pairs LVL1

## Getting HLT Rate

| Origin | Contribution |
| --- | --- |
| e from b,c decays | 25 % |
| e from conversion | 17 % |
| We decays | 17 % |
| Zee decays | 7 % |
| others | 34 % |

- From HLT TDR

- Update this year e25i
- Fraction of final rate

## Muons

## Muon Cross Sections

## Jets

## More Jets

## Jet Rates

## Missing ET + 1 jet

## SUSY Example

- Ongoing studies of full simulation of SUSY events in “co-annihilation region”.
- See recent talks by Pavel
- http://agenda.cern.ch/askArchive.php?base=agenda&categ=a045055&id=a045055s1t1%2Ftransparencies%2FNovember_18.ppt
- Or Davide
- http://agenda.cern.ch/askArchive.php?base=agenda&categ=a044275&id=a044275s6t8/transparencies
- Soft leptons – see next page
- Desire to trigger on these events with missing ET+1jet trigger

## Lepton Spectra

**p****T**** distribution for leading and soft electrons that are used to calculate dilepton invariant mass. **

**p****T**** distribution for leading and soft muons that are used to calculate dilepton invariant mass.**

**leading e **
**soft e**

**leading muon **
**soft muon**

**p****T**** for leading and soft electrons**

**p****T**** for leading and soft muons**

## SUSY Example

| Event# | xE | Jet 1 | Jet 2 | Jet 3 | Jet 4 |
| --- | --- | --- | --- | --- | --- |
| 1 | 255 | 295 | 206 | 170 | 43 |
| 2 | 570 | 579 | 298 | 92 | 76 |
| 3 | 678 | 785 | 69 | 52 | 25 |
| 4 | 343 | 819 | 704 | 46 | 12 |
| 5 | 163 | 225 | 133 | 38 |  |
| 6 | 98 | 152 | 117 | 90 | 84 |
| 7 | 540 | 759 | 452 | 215 | 72 |
| 8 | 420 | 470 | 268 | 101 | 82 |
| 9 | 392 | 300 | 200 | 78 | 64 |
| 10 | 45 | 42 | 25 | 12 |  |

**j****70**** + xE****70**

**j****400****, 3j****165****, 4j****110**

## Possible Future Topics?

- Trigger algorithms for specific objects eg. what is an electron
- Just reading but educational
- Straightforward to do from various TDRs and presentations
- Cross sections and simple spectra (ddET)
- Many pieces, each by someone?
- Generators, simulation....needed
- Non-trivial amount of work....need to understand better what is already done or underway