Enhancements in Tracking Algorithm Efficiency and Constants for DESY and CERN

1. Tracking/Alignment Status Paul Dauncey, Michele Faucci Giannelli, Mike Green, Anne-Marie Magnan, George Mavromanolakis, Fabrizio Salvatore, Hakan Yilmaz Tracking - Paul Dauncey

2. Track finding/fitting changes • Checks all hits for consistent track combinations • Previously only used first hit in each chamber • Allows more (or less) than one track per event • Previously always one (unless a chamber had zero hits) • Allows for missing hits on track • Previously only had four-hit tracks • Allows for non-perfect alignment • Previously assumed all chamber placement was ideal • Same code for CERN and DESY • Different constants but algorithm is identical • Missing layer in CERN just appears inefficient Tracking - Paul Dauncey

3. Constants status • Have first version of tracking constants for Run 230101 • Michele has checked drift velocity against other runs • Sees values are mostly stable to ~0.0006mm/ns ~ 2% • Scattering matrices found for all DESY energies • CERN runs put to zero scattering until calculated Tracking - Paul Dauncey

4. Mokka changes • X and Y gas drift volumes physically separated • Displaced in z by 44mm at DESY, 29mm at CERN • Split sensitive volumes into two parts • Removes correlation in energy deposits • All SimTrackerHits in one collection • Labeled by CellID; similar to calorimeters • Chamber numbering made more uniform • DESY was (from ECAL) DC2, DC1, DC3, DC4 • CERN was (from ECAL) DC3, DC2, DC1 • Small effect on tracking • X/Y split only at 1% level • Big effect on digitisation code and book-keeping • DESY and CERN look much more similar • Debug most of digitisation code only once Tracking - Paul Dauncey

5. Fabrizio N.B. Neighbouring chambers placed 1100mm centre-to-centre Tracking - Paul Dauncey

6. Fabrizio Tracking - Paul Dauncey

7. Digitisation changes • Seed digitisation for every event from event number • Repeatable if debugging event in middle of run • Using ROOT gRandom; is this the standard? • Allow more than one TDC hit per event • Previously only first SimTrackerHit per layer used • Incorporate SimTrackerHit times • Some hits from preshowers significantly later • Can overlap with real track in space but sometimes not in time • Add TDC noise hits • Currently flat distribution with rate matched to DESY data • Check rate of random hits picked up by tracking • Simulate efficiency < 1 • Simply drops hits randomly • Tune hit smearing to agree better with data Tracking - Paul Dauncey

8. Michele Need to cross check against efficiency for track to have hits Tracking - Paul Dauncey

9. Simulation request • Add Fabrizio’s changes before big Mokka production run • Otherwise need to maintain many different versions • Change of coordinate system also means “fresh start” would be good • Need high statistics samples for all DESY energies • Also electrons and pions for all CERN energies (at lower priority) • Need to smear beam position and angle to duplicate data better • Many distributions look quite different otherwise Tracking - Paul Dauncey

10. Want to align ECAL to beam separately • Decouples systematics of each detector • Allows clean comparison of tracking to ECAL for position measurement • Problem is determining average beam position = 0 • Barycentre distorted by ECAL pad granularity • Difference in x and y due to x layer staggering Tracking - Paul Dauncey

11. Hakan Mean shifted by 1mm Corrected using smoothing (integral) function; assumed Gaussian Tracking - Paul Dauncey

12. Code organisation Tracking - Paul Dauncey

13. Code status • Code structure now effectively defined • Sent to Roman; he will try it out • If it works in his set-up, then load to cvs • Remaining issue is database access • Working with faked up version currently • Not all runs will work until true database interface • RunHeader: request for LCParameters information • Need run number set for MC • Also generally need • Data or MC flag • Run start/end times • Nominal beam energy • Location (DESY, CERN, FNAL later) • Do these exist? Can missing items be added as part of reconstruction? Tracking - Paul Dauncey

14. Next steps • Need to reprocess at least one run of each DESY energy • E.g. 230097 - 230104 • Best done centrally to check for interference • Cross check all alignment and constants including ECAL changes • If time, then repeat for CERN runs • Need MC to evaluate scattering matrices for every energy • Most of code is directly usable • Need to re-evaluate (carefully) alignment, drift velocity • Need to re-evaluate (roughly) efficiency, noise rate • May not converge for LCWS… • Must ensure DESY results are available first • Minimum for LCWS; must take priority Tracking - Paul Dauncey