1. Timing/Synchronization Status
Greg Rakness
University of California, Los Angeles
CMS EMu-ME1/1 Meeting
CMS Week
11 December 2007
Synchronization parameter predictions—update
Trigger configurations underground
Proposal for how to synchronize during commissioning
Some details on ME1/1 chambers
11 Dec 2007
G. Rakness (UCLA)

2. Synchronization Predictions Update
Recall: Initial xml files generated by c++ code for all 468 chambers
Prediction of synchronization parameters based on cable/fiber lengths
Description at
New: Now includes ALL AFEB fine delays and thresholds (N. Terentiev, CMU; A. Korytov, UF; M. Ignatenko, UCLA)
For detailed description, see Nikolai’s talk at
When available, based on values from latest SX5 tests. When not available, ISR or FAST site tests…
For ME1/1: Delay settings calculated from cable lengths, using constant DAC/nsec conversion (“should be remeasured ASAP”)
No time-of-flight correction included
11 Dec 2007
G. Rakness (UCLA)

3. Synchronization Predictions (cont.)
New: Now has explicit latency for each component (TMB, ALCT, Global Trigger, etc.)
For example, if L1A latency changes, change one number in code; if ALCT firmware changes, change one (other) number in code…
To be done:
Tie L1A-latency for CFEB to L1A-latency for ALCT/TMB
Implement Time-Of-Flight correction
Make latency change algorithms work on measured parameters (from xml files), too
11 Dec 2007
G. Rakness (UCLA)

4. CSC Trigger Configurations
Summary of discussion:
For global data runs, LHC pattern trigger most useful (best for Track Finder, DPG work, emulator)…
For other purposes, these rates are too low…
Trigger primitive configurations available:
LHC pattern trigger  muon pointing to IP
Plusses: real muons trigger nominal pattern
Minuses: 0.3 Hz/chamber (for TS1 in USX55)
Layer trigger  CSC ~ scintillator paddles
Plusses: expect ~ 6 * LHC pattern rate
Minuses: no wiregroup nor ½-strip info in trigger; steep tracks; different ALCT firmware needed
“Radioactive” trigger  natural radioactivity in and around chamber
Plusses: expect ~ 100 * LHC pattern rate
Minuses: not real muons
Testpulse trigger  pulse test strip
Plusses: no HV needed; adjustable rate
Minuses: strange “muons” in CFEB data; no drift time; no time-of-flight
11 Dec 2007
G. Rakness (UCLA)

5. Compare Testpulse vs. Cosmic Ray Timing
DQM results of ALCT-CLCT matching for cosmic rays with LHC pattern trigger using sync parameters from testpulsing centered at 3.5
Distribution of mean values from all chambers:
Worst case:
ME+2/1/2
(Run _115437)
Window size = 7
Best value
Synchronization values from high rate triggers consistent with values for LHC pattern trigger (with wide windows)
11 Dec 2007
G. Rakness (UCLA)

6. Proposed Path to Synchronization
Open up coincidence windows
Start with parameter predictions from cable lengths
Synchronize each chamber by itself online with radioactive trigger
Take a long data run with LHC pattern trigger on cosmic rays
Use DQM results and Sector Processor analysis to line up:
LCTs from different chambers at the Sector Processor
ALCT with CLCT for each chamber
Adjustment of L1A receipt delays for DAQ readout
Take another run: data will show if trigger path is synchronized
May need to fine tune L1A receipt delays for DAQ readout… (N.B. only tools available are online scans…)
Shrink coincidence windows (eventually)
11 Dec 2007
G. Rakness (UCLA)

7. Proposed Path to Synchronization: Open Questions…
How long of runs are needed for LCT alignment at Sector Processor?
Use layer trigger to increase coincidence rate?
Possible to add information to data headers to monitor DAQ synchronization directly?
L1A position in matching window for TMB, ALCT, CFEB
DAV scopes in DAQ readout
11 Dec 2007
G. Rakness (UCLA)

8. Emulator Based Rate Projections (D. Wang, UF)
Method: Full simulation, combined with proper normalization factors for the samples, can estimate cosmic rays underground for all CSCs
Standard CMS cosmic simulation samples
Generator: CMSCGEN
Total rates of cosmic muon in CMS underground: 650Hz (From K. Hoepfner)
Preliminary results for ME1:
Ring 1: Hz
Ring 2: ~0.3Hz
Ring 3: ~0.4Hz
Preliminary results for ME2, 3, 4:
Ring 1: ~0.4Hz
Ring 2: ~1.0Hz
Trigger Sector distributions of cosmic rays at bottom right +Z -Z
11 Dec 2007
G. Rakness (UCLA)

9. Synchronization Issues for ME1/1
Synchronization of ME1/1 with full system limited to MTCC
Essential differences between ME1/1 and other chambers include…
Orientation of chambers require four types of ALCT firmware (forward/backward + plus/minus endcap)
Type of firmware to be loaded is specified in xml file
At configuration, direct check of ALCT firmware version read from fast control FPGA register
One type of slow control firmware
For AFEB fine delays and thresholds, AFEB  ALCT input channel mapping will require reversal of loading for 2 of the 4 types of ALCT
No staggering of strips
VME register on TMB has bit “csc_stagger” to account for non-staggering of ME1/1 strips
No teststrip
Will need to use radioactive trigger to synchronize
11 Dec 2007
G. Rakness (UCLA)

10. Backup slides…
11 Dec 2007
G. Rakness (UCLA)

11. Cosmic rays above and below ground…
Going from above ground (SX5) to 100m below ground (USX55)…
Changes to muon spectra addressed in L.N. Bogdanova, et al., Phys. Atom. Nucl. 69 (2006) 1293; arXiv:nucl-ex/ v1
 Angular distribution of muons similar under 100m solid rock as on surface…
[Will be modified due to shaft… i.e., minus end will see more vertical muons]
 Rate in USX55 is ~1% rate in SX5…
Q: How to increase the trigger rate to synchronize downstairs?
A: Expand the scope of CSC triggers beyond “normal” LHC muons…
11 Dec 2007
G. Rakness (UCLA)

12. New n-Layer Trigger
Concept: trigger on any muon which traverses the chambers… CSCs  large scintillators with wider angular acceptance
Configuration:
ALCT and CLCT layer fire on any hit within a layer
Require minimum number of layers for ALCT (CLCT) trigger (same as for pattern trigger)
Trigger on ALCT*CLCT match
Rate  6x LHC muon pattern trigger on cosmics
Large angular acceptance enables online determination of ALCT and CLCT efficiencies using TMB counters
Typical “efficiencies”: ALCT  99.9%, CLCT  99.1%
See recent DPG talk by J. Hauser (
11 Dec 2007
G. Rakness (UCLA)

13. New Radioactive Trigger
Concept: trigger on (low energy ?) particles resulting from radioactivity in and around chambers
Configuration:
ALCT and CLCT each fire on a single layer
normal pattern and n-Layer trigger are identical w.r.t radioactive trigger
Trigger on ALCT*CLCT match
Rate = 100x LHC muon pattern trigger on cosmics (including cosmic ray “background”)
~95% of CLCT pretriggers match with ALCT
Large fraction of real coincidences
Uniform distribution in layer and position
Sensitive to single hot channels in ALCT and CLCT
Need hot channel mask…
11 Dec 2007
G. Rakness (UCLA)

14. CSC Test Strip Pulsing
Recall: CSCs equipped with test strip (= extra cathode strip) which can be pulsed by TTC command (ADB sync) through CCB  ALCT
Pulsed test strip induces signal synchronously on both anode wiregroups and on cathode strips in the CSC “waveguide”… can be used to trace “muon” signals through trigger and DAQ
amplitude = 20
di-strip CLCT0
Components are blind to source of signals (i.e., AFEB, CFEB, ALCT, TMB, DMB…)
Two signals are induced for each ADB sync signal, both on leading and rising edge…
pulse length = 550 nsec
Successfully used to trigger CSCs from Global Trigger in end of September Global Run
Number of triggers seen versus distrip for 100 pulses
di-strip 0 masked off, since it rings hot when test strip enabled
No data beyond di-strip 8
11 Dec 2007
G. Rakness (UCLA)

15. Fiber lengths from TTC  CCB
Differences corrected by CCB TTCrq parameters TTCrxCoarse[Fine]Delay…
Setup
Avg. (m)
Min. (m)
Max. (m)
MTCC YE+1
150
MTCC YE+2
160
Minus side slice test
ME+1
74.1
59.9
83.9
ME+2
91.8
84.0
101.0
ME+3
91.7
83.0
ME+4
98.7
88.0
112.0
In contrast to MTCC, final fiber lengths differ by as much as ~10 bx…
Assume these numbers reflect MPC  Sector Processor fiber length differences
SP firmware upgrade required to pass ME1 trigger primitives to Drift Tube Track Finder before ME4 arrives to keep CSC off the latency critical path…
11 Dec 2007
G. Rakness (UCLA)