1. Status of CMS and the Austrian Contribution to the Trigger System

2. The CMS Collaboration 1809 Physicists and Engineers 31 Countries
Number of
Laboratories
Belgium
Austria
Bulgaria
Member States 58
USA
CERN
Finland
Non-Member States 50
USA 36
France
Total
144
Germany
Russia
Number of
Scientists
Greece
Uzbekistan
Hungary
Member States
1010
Ukraine
Italy
Slovak Republic
Non-Member States
448
Georgia UK
USA
351
Belarus
Poland
Armenia
Turkey
Total
1809
India
Spain
Portugal
Taiwan
Korea
China
Estonia
Pakistan
Switzerland
Cyprus
Associated Institutes
Number of Scientists
Number of Laboratories 36 5
Croatia
1809 Physicists and Engineers
31 Countries
144 Institutions
July, 26th, 2000
Claudia-Elisabeth Wulz

3. The CMS Detector
The CMS detector is designed to analyze proton-proton and heavy-ion collisions at CERN’s Large Hadron Collider. Its diameter is 15 m, its length is 21.6 m and its weight is approximately tons.
Claudia-Elisabeth Wulz

4. Assembly of First Magnet Wheel
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5. Site of the CMS experiment
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6. Muon Chamber Assembly
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7. CMS Main Physics Goals Standard Model Higgs (if not confirmed at LEP)
Supersymmetric Higgses
Other supersymmetric particles
Claudia-Elisabeth Wulz

8. Principles of Triggering in CMS
The purpose of the trigger system is the selection of all interesting events in the presence of an overwhelming background. CMS has a hierarchical trigger system, consisting of a First Level, a Second Level and several Higher Level Triggers.
The First Level Trigger is a custom designed electronics system, the Higher Level Triggers are all commercially available processors.
The First Level Trigger has to take a decision within 3.2 ms, determined by the size of the currently available analog pipeline memories for the tracker.
At the LHC design luminosity of 1034 cm-2s-1 about 25 inelastic proton-proton collisions occur every 25 ns corresponding to an interaction rate of about 1 GHz. The First Level Trigger must reduce this rate to 100 kHz, the maximum tolerable input rate to the Second Level Trigger. Events can be written to mass-storage with a rate of 100 Hz.
The First Level Trigger has to provide an accept/reject decision (L1A) for every bunch crossing. It therefore has to run dead-time free.
Claudia-Elisabeth Wulz

9. CMS First Level Trigger
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10. CMS Global Trigger Global Trigger Environment
For physics running the Global Trigger uses only input from the calorimeters and the muon system. The data used for triggering are relatively coarse. The high resolution data are used by the Higher Level Triggers. Special signals from all sub-systems may be used for calibration, synchronization and testing purposes (technical triggers).
The TTC System is an optical distribution tree that is used for the transfer of the Level-1 Accept signal and timing information (LHC clock etc.) between the trigger and the detector front-ends.
The Trigger Control System controls the delivery of L1A signals and issues bunch crossing zero and bunch counter reset commands. There is a facility to throttle the trigger rate in case of buffers approaching overflow conditions.
The Event Manager controls the Higher Level Triggers and the data acquisition.
Global Trigger Environment
Claudia-Elisabeth Wulz

11. Typical Trigger Conditions
Trigger Thresholds/GeV Examples of explorable physics channels
1 m 15 HSM, H, A, H±, W, W’, t, B-physics channels
2 m 5, 5 HSM, h, H, A, Z, Z’, V, , LQ, Bs0 -> 2m, , ’, ’’
m+e/g 5, HSM, H, A, t, WW, WZ, Wg, , V
m+jet(s) 5, HSM, h, H, A, , LQ, t
m+ETm 5, 100 t, , LQ, WW, WZ, Wg
1 e/g 20 HSM, h, H, A, W, W’, t, B-physics channels
2 e/g 15, 15 HSM, h, H, A, Z, Z’, WW, WZ, Wg, , LQ
2 jets 60, 60 QCD
e/g+jet(s) 15, 60 HSM, h, H, A, , LQ, QCD (g +jets, W+jets)
m+t 5, 20 HSM, H, A,
e/g+t 15, 20 HSM, H, A,
t+jets 15, 60 H±
jets+ETm 60, , H±
Claudia-Elisabeth Wulz

12. Algorithm Logic Initial step: Particle and Delta Conditions
The first are applied to a group of objects. The conditions are: ET or pT thresholds, h/f-windows, bit patterns for isolation, quality, charge, and spatial correlations (Dh, Df) between objects of the same type. Delta Conditions calculate spatial correlations between different objects.
Particle Condition for
2 back-to-back isolated electrons
Particle Condition for 2 back-to-back
isolated opposite-sign muons
with MIP bits set
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13. Algorithm Logic Next step: Actual algorithm calculations.
Logical combinations (AND-OR) of objects
are determined.
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14. Algorithm Logic
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15. Global Trigger Logic Hardware
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16. Implementation of First Level Trigger
PSB (Pipeline Synchronizing Buffer) Input synchronization
GTL (Global Trigger Logic) Logic calculation
FDL (Final decision logic) L1A decision
TIM Timing
GTFE (Global Trigger Frontend) Readout
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17. PSB Prototype
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18. Conclusions and Outlook
CMS construction (detector components and experimental area)    is well under way.
First physics runs are expected in 2005/2006.
Austria is responsible for crucial parts of the trigger system   (Global Trigger, Global Muon Trigger and Barrel Track Finder).
All three contributions are well advanced. The design is   practically finished. Prototypes of the critical items either exist   (PSB) or are nearing completion (GTL).
Claudia-Elisabeth Wulz