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Latency and Synchronization update

Latency and Synchronization update. Latency: Sources of numbers. previous numbers were measured! Components individually measured/understood by responsibles* except the CSC-->DT part . UCLA RICE Florida System measured as a whole during 2003 testbeam

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Latency and Synchronization update

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  1. Latency and Synchronization update

  2. Latency: Sources of numbers • previous numbers were measured! • Components individually measured/understood by responsibles*except the CSC-->DT part. • UCLA • RICE • Florida • System measured as a whole during 2003 testbeam • System partially re-measured 2005 at slice-test • System partially re-measured 2006 at MTCC & overall validation vs DT arrival time @ GMT understood. • The new numbers presented today reflect well-understood “deltas” from previous estimates

  3. (Previous) Chamber + Peripheral Crate 11m cables to GMT MPC Chamber, CFEB, AFEB, ALCT 94m optical fibers MS 14.5m cable TMB/CLCT SP

  4. (previous) ..add it up: Critical path

  5. CSC  DTTF Critical Path • This path is too slow: • CSC primitives a bit slower than TDR estimate • DTTF a bit slower than TDR estimate • CSC primitives arrive at DTTF at 67 bx • (this path not broken out in the TDR) • Revised estimate using TMB2005 firmware • 64.2 bx CSC primitives arrive at DTTF • New estimate using TMB2007 firmware • 62.2 bx CSC primitives arrive at DTTF

  6. (TMB2005) Chamber + Peripheral Crate 11m cables to GMT MPC Chamber, CFEB, AFEB, ALCT 94m optical fibers MS 14.5m cable TMB/CLCT SP

  7. Revised estimate using TMB2005 firmware • CSCDTTF total 6764.2 bx, difference is -2.8 bx • Front-end is +1.2 bx: • -0.8bx because critical path is actually ME4/1, not ME1/1 (longer optical fibers to SP), Skewclear are shorter. • +1.0bx maximum drift delay 3 bx, not 2bx. • +1.0bx because comparator delay to peak of CFEB amplifier output better set at 3 bx, not 2 bx. • TMB processing is -3 bx: • previously waited for ALCT before CLCT started “pretrigger” stage (configuration mistake, i.e. “pilot error”) • 19 bx  16 bx (TDR was 15.5) • TMBMPC is -1 bx: • previously overestimated backplane propagation as 2 bx

  8. New estimate using TMB2007 firmware • CSCDTTF total 6762.2 bx, difference is -4.8 bx • TMB processing 1614 bx: • -1.0 bx in CLCT processing I/O synchronization: input from CFEB save 0.5 bx, output to TMB matching logic with ALCT save 0.5 bx. • -1.0 bx in internal processing of ALCT-CLCT matching.

  9. Details:

  10. Latency Summary • CSC-TF path: • Previous estimate 80.5 bx • This is reduced to 77.7 bx currently • Reduces to 75.7 bx with new firmware (compare to TDR 78 bx) • CSCDTTF path: • Previous estimate 67 bx • This is reduced to 64.2 bx currently • Reduces to 62.2 bx with new firmware • No TDR estimate, but DTTF waits for CSC primitives starting at bx 60 (Janos Ero, longer-than-anticipated optical cables)

  11. Synchronization spreadsheet update • Spreadsheet: re-ordered plots sensibly and added a “key” to describe all the Excel plots

  12. Sync Spreadsheet: updating parameters after “pilot error” fix • L1A timing looks much more sensible

  13. Comments • Data taken with various comparator thresholds • Quick look: 12mV best? Would like to verify with DQM and other offline study • Use 12 mV for subsequent studies • Best trigger timing settings? • Data taken with various drift_delays for ALCT and CLCT • Data taken with various comparator delays to peak • Data taken with various “triad persistence” values • NEED information on what happens to trigger efficiencies • Also need to run with new pattern-finding firmware as soon as it’s ready to verify some of the settings.

  14. ALCT fine delays • Dayong “test” of analysis: revert to old firmware phases, try diddling fine delays a little, take data and see if he can find the offset. • Also, a few typos to fix (mine) in getting from Misha’s numbers to the XML file. • Otherwise, new TMB clocking phases should result in constant offset in clock time to all ALCTs, should be invisible to cosmic ray data – to verify. • Then, apply Dayong corrections – is relative timing perfect? • I still want to “predict” ALCT fine delays with spreadsheet… just need a few hours analysis time…

  15. Comments I • Best trigger timing settings? • 12 mV deemed best comparator threshold, but is it? • Data taken with various drift_delays for ALCT and CLCT • Data taken with various comparator delays to peak • Data taken with various “triad persistence” values • NEED information on what happened to trigger efficiencies • New pattern-finding firmware: • We’d like to verify some of the timing settings (some will change, e.g. pretrigger earlier with 2 layers rather than 4). • Changes to CLCT/TMB emulator code will be needed (Slava).

  16. Comments II • TMB qualities: 4-bit = 16 choices: 6 di-strip qualities gone • Can get by for now just using 10 out of 16 qualities • Slava: reassignment of qualities should be intimately connected with accelerator vs. collision muons question. • Nobody thought through accelerator muons all the way: • Tailor ALCT collision patterns specific to chamber? • ALCT accelerator patterns switched on? • What priority do accelerator muons have? (currently TMB  low quality, but people do want accel. muon trigger) • The SP doesn’t yet handle accelerator muons appropriately (horizontal coincidence)

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