29 mar 2007tracking - paul dauncey1 tracking/alignment status paul dauncey, michele faucci...
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29 Mar 2007 Tracking - Paul Dauncey 1
Tracking/Alignment Status
Paul Dauncey, Michele Faucci Giannelli, Mike Green, Anne-Marie Magnan, George Mavromanolakis, Fabrizio Salvatore, Hakan Yilmaz
29 Mar 2007 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
29 Mar 2007 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%
Run Energy DC1 DC2 DC3 DC4
230097 3 0,0305 0,0284 0,0346 0,303
230098 1 0,031 0,0282 0,0386 0,0292
230099 2 0,0305 0,0284 0,035 0,0303
230100 4 0,0305 0,0282 0,0345 0,0302
230101 6 0,0303 0,0282 0,0342 0,0301
230104 5 0,0301 0,0278 0,034 0,0299
230255 1,5 0,0299 0,0278 0,0339 0,0294
• Scattering matrices found for all DESY energies• CERN runs put to zero scattering until calculated
29 Mar 2007 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
29 Mar 2007 Tracking - Paul Dauncey 5
N.B. Neighbouring chambers placed 1100mm centre-to-centre
Fabrizio
29 Mar 2007 Tracking - Paul Dauncey 6
Fabrizio
29 Mar 2007 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
29 Mar 2007 Tracking - Paul Dauncey 8
Need to cross check against efficiency for track to have hits
Michele
29 Mar 2007 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
29 Mar 2007 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
29 Mar 2007 Tracking - Paul Dauncey 11
Hakan
Corrected using smoothing (integral) function; assumed Gaussian
Mean shifted by 1mm
29 Mar 2007 Tracking - Paul Dauncey 12
Code organisation
29 Mar 2007 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?
29 Mar 2007 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