1. FD Timing Calibration Status Guardians of the FD timing calibration: –John Chapman, graduation in ~3-6 months. –Andy Blake, renewal of contract (or redundancy!) in ~1 year. Current status of DB constants: –Currently: August 2003 – April 2006. –Pending: April 2006 – June 2006. –Processing data in ~2-3 month batches. Documentation: –Everything described in AB’s thesis + timing webpage. –Two new documents in preparation: (1) timing calibration algorithm. (2) timing calibration implementation. –But still work in progress (so no doughnuts for Andy  ). Andy Blake, Cambridge University Fermilab, September 2006

2. (1) Calibration Algorithm MEASURE REFRACTIVE INDEX TIME WALK CORRECTION TIMING JUMPS (hardware changes + drift) STRIP-TO-STRIP TIMING CONSTANTS STEP 1 STEP 2 STEP 3 STEP 4 Andy Blake, Cambridge University Fermilab, September 2006

3. (2) Calibration Implementation (i) PROCESS DATA TO STRIP LEVEL (ii) SELECT CLEAN MUONS (iii) OUTPUT CALIBRATION NTUPLES (i) FIND TIMING JUMPS. (ii) (CALCULATE S2S CONSTANTS). (i) VALIDATE TIMING CONSTANTS. (ii) COMMIT TO DATABASE. STEP 1 STEP 2 STEP 3 Andy Blake, Cambridge University Fermilab, September 2006

4. Validation of Calibration mean east-west time vs. channel number Nov’04 – Apr’05 Apr’05 – Sep’05 Sep’05 – Feb’06 ± 2.5 ns Andy Blake, Cambridge University Fermilab, September 2006 108*crate + 36*varc + 6*vmm + 3*vaadc + vachip

5. Some Calibration Issues Upward muon analyses seem to work! –Good, timing calibration is approximately correct! Some assorted timing calibration questions: –By how much does the S2S calibration drift? Currently use same set of constants for entire period. –By how much does the time walk drift? Currently use same correction function for entire period. Correction is only based on raw ADC value. –Is there any significant short term drift? Do GPS and PPS track each other uniformly across detector? –Do the data and MC agree well enough? Timing distributions can’t all be made to agree simultaneously! Andy Blake, Cambridge University Fermilab, September 2006