2. CMS Detector at the CERN Large Hadron Collider
C. - E. Wulz

3. Cross Sections and Rates
Cross sections for different processes vary by many orders
of magnitude
inelastic: Hz
W -> ln: Hz
tt: Hz
Higgs (100 GeV): Hz
Higgs (600 GeV): Hz
Required selectivity
1 :
Trigger -
C. - E. Wulz

4. CMS Level-1 Trigger Only calorimeters and muon system involved
Reason: no complex pattern recognition as in tracker required (appr tracks at 1034 cm-2s-1 luminosity), lower data volume
Trigger is based on:
Cluster search in the calorimeters
Track search in muon system
C. - E. Wulz

5. Level-1 Trigger and Institute Responsibility
Calorimeter Trigger
Muon Trigger HF
HCAL
ECAL
RPC
CSC DT
Local CSC Trigger
Local DT Trigger
Regional Calorimeter Trigger
Pattern Comparator Trigger
CSC Track Finder
DT Track Finder
40 MHz pipeline, latency < 3.2 ms
Global Calorimeter Trigger
4+4 m
4 m
4 m
MIP+ ISO bits
Global Muon Trigger
e, J, ET, HT, ETmiss
4 m (with MIP/ISO bits)
Global Trigger
Responsibility
of Vienna Institute
max. 100 kHz L1 Accept
C. - E. Wulz

6. System Overview Global Trigger + Global Muon Trigger: 1 Rack
Drift Tube Track Finder: 3 Racks
C. - E. Wulz

7. Muon Trigger Detectors
Drift Tube Chambers and Cathode Strip Chambers are used for
precision measurements and for triggering.
Resistive Plate Chambers (RPC’s) are dedicated trigger chambers.
C. - E. Wulz

8. Barrel Muon Chambers
Mounting of a Drift Tube Chamber into the iron yoke
C. - E. Wulz

9. Cathode Strip Chambers on endcap iron yoke
Endcap Muon Chambers
Cathode Strip Chambers on endcap iron yoke
C. - E. Wulz

10. Transport of the First Magnet Coil Module
A good muon trigger needs a high magnetic field!
C. - E. Wulz

11. Regional Muon Trigger Track Finder Processor Drift Tubes
Pipeline logic running at 40MHz
(LHC bunch crossing frequency)
Implemented in programmable logic
devices
Based on extrapolation and pattern
matching methods
Drift Tubes
(CSC’s similar)
C. - E. Wulz

12. Drift Tube Trigger Track Finder
Track segment (with direction of extrapolation)
Phi Track Finder
(Sector Processor)
Eta Track Finder
The trigger is based on correlating compatible track segments pointing to the vertex. At most four detector planes are used in azimuth (transverse to the magnetic field direction) and three in pseudorapidity (along the beam axis). If possible, track candidates found in both projections are then matched.
C. - E. Wulz

13. Muon Trigger Prototypes
Sector Processor
Timing Module
Wedge Sorter (Bologna)
Trigger Crate
Eta Track Finder
C. - E. Wulz

14. Best 4 m Global Muon Trigger DR/CSC/RPC: combined in
Global Muon Trigger, isolation and MIP information added
252 MIP bits 252 Quiet bits
4 m RPC barrel
4 m DT
Inputs: 8 bit f, 6 bit h, 5 bit pT, 2 bits charge, 3 bit quality, 1 bit halo/eta fine-coarse
Best 4 m
4 m CSC
Output: 8 bit f, 6 bit h, 5 bit pT, 2 bits charge/synch, 3 bit quality, MIP bit, Isolation bit
4 m RPC forw.
C. - E. Wulz

15. Global Muon Trigger Efficiencies
Optimal combination high efficiency, small rate
2.0
87.4
AND
2.9
97.3
SMART
5.4
98.1 OR
Rate
kHz
for 14 GeV
e % |h|<2.1
GMT Option
Rates for L=2x1033 cm-2s-1 DT
CSC
RPC
GMT smart
Muon Trigger Efficiency
GMT OR
GMT AND
GMT smart
Sophisticated, flexible algorithm
using geometry and quality to achieve:
good efficiency
reasonable rates
ghost suppression
GMT Efficiency
C. - E. Wulz

16. Hadron Calorimeter Barrel Hadron Calorimeter
Forward Hadron Calorimeter
The Global Muon Trigger adds information to muon candidates by correlating them with calorimeter regions. It confirms muon candidates with MIP information and determines their isolation.
C. - E. Wulz

17. Global Trigger
The trigger decision may be based on simple or more complex criteria, similar to data analysis:
Logic combinations of trigger objects sent by the Global Calorimeter Trigger and the
Global Muon Trigger
Best 4 isolated electrons/photons ET, h, f
Best 4 non-isolated electrons/photons ET, h, f
Best 4 jets in forward regions ET, h, f
Best 4 jets in central region ET, h, f
Best 4 t-Jets ET, h, f
Total ET SET
Total ET of all jets above threshold HT
Missing ET ETmissing, f(ETmissing)
12 jet multiplicities Njets (different ET thresholds and h-regions)
Best 4 muons pT, charge, f, h, quality, MIP, isolation
Thresholds (pT, ET, NJets)
Optional topological and other conditions (geometry, isolation, charge, quality)
C. - E. Wulz

18. Global Trigger Algorithms
Object Conditions
Logical Combinations
128 flexible algorithms running in parallel are implemented in programmable logic devices. The trigger decision (Level-1-Accept) is a function of the 128 trigger algorithm bits (for physics). 64 more technical algorithms are possible.
C. - E. Wulz

19. Global Trigger Boards
Every 25 ns the Global Trigger takes the decision to reject an event or to make it available to the High Level Trigger for further consideration. It consists of the following electronics boards:
PSB (Pipelined Synchronizing Buffer) Synchronization of inputs (7 modules)
GTL (Global Trigger Logic) Logic (1-2 modules)
FDL (Final Decision Logic) Trigger decision (1 module)
TCS (Trigger Control System Module) Central trigger control (1 module)
L1A (Level-1 Accept Module) Distribution of trigger decision (1 module)
TIM (Timing Board) Timing (1 module)
GTFE (Global Trigger Frontend) Readout (1 module)
PSB (Pipelined Synchronizing Buffer)
GTL (Global Trigger Logic)
C. - E. Wulz

20. Trigger Control System and Timing
Trigger Control System Module
Timing Module
The TCS Module controls the data taking based on fast status signals sent by the subsystems. The Timing Module is used for the distribution of the LHC clock.
C. - E. Wulz

21. Physics, Software, Management
Trigger studies (Level-1, High Level Trigger)
Software for testing and operation of the trigger hardware
Coordination of the complete level-1 trigger software
Software for the reconstruction of muons
Preparations for physics analysis, especially with
studies in the field of Supersymmetry
Membership in CMS Management Board
Membership in Editorial Boards for Trigger and
Physics Reconstruction and Selection
C. - E. Wulz

22. Summary
The CMS-Trigger Group of the Vienna Institute for High Energy Physics is responsible for the Level-1 Drift Tube Track Finder, the Global Muon Trigger and the Global Trigger and is developing software for triggering. It is working on the reconstruction of muons and is performing studies for physics analysis, in the field of supersymmetry.
The current group members are:
Scientists (physics, electronics, computer science):
J. Erö, M. Jeitler, A. Nentchev,
N. Neumeister, P. Porth,
H. Rohringer, H. Sakulin,
J. Strauss, A. Taurok, C.-E. Wulz
Technicians:
H. Bergauer, Ch. Deldicque,
K. Kastner, M. Padrta
Students:
M. Galánthay, S. Kostner, B. Neuherz
C. - E. Wulz