Flow Description

• Perform crude extrapolation to disk or cylinder at the entry to the muon inner stations
• Correct the momentum of the particle candidate to account for energy loss in the calorimeter using MuidCaloEnergyTool
• All extrapolations of intersections are done using RungeKutta
• The algorithm progresses from one combination of distance (inner, middle, etc.) and region (barrel, endcap) to another
• For each such combination, the information gathered thus far is used to open a road in η/φ, select chambers reachable in the road, select hits in the road, and create segments form these hits. The details depend on the technology (MDT, RPC, TGC, CSC), distance and region
• The road width depends on our confidence in the extrapolation as estimated using single muon samples. The width is affected by the estimated p_T of the candidate, the presence of hits/segments in other parts of the muon spectrometer, etc.
• Chambers are selected using RegSelSvc where possible, direct enumeration methods where the region selector does not operate
• The η value of η hits is corrected as a function of the φ of the track before they are tested against the road
• Segments are built using different algorithms for different technologies
  • The Hough MDT segment maker is used for the MDT stations
  • A simple average point is calculated for the TGC in the inner station
  • A straight line is estimated for the TGC in the middle station. Points that are far from the line (contributing a Χ² of 10 or more) are succeessively removed from the fit. If there are not enough points (less than 4), a simple average is used here too. In this case the direction of the segment is borrowed from a previous extrapolation
  • RPC middle... outer...
  • CSC...
• For the inner distance:
  • In the endcap
    • Extrapolate the ID track from the entry to the inner disk to each TGC chamber in the selected list
    • Select TGC hits in the road, estimate the position of the intersection of the candidate track with the inner station. Use the direction of the extrapolated track (only 2 close hits in TGC Inner station) to create a segment (if too few hits?). The intersection derived from this segment will be the starting point for the next step
  • In the barrel
    • Use the intersection of the extrapolated ID track as a starting point
  • Use the intersection from the previous step to open a road and select MDT chambers
    • Check the possibilty of combining the position and direction information from the extrapolated track and the trigger tracklet
  • Extrapolate the best available intersection to each chamber and select MDT hits in a road around it
  • Create caliberated hits (MdtDriftCircleOnTrack) using MdtDriftCircleOnTrackCreator
  • For each MDT station (one or two chambers) build segments using MDT_DHoughSegmentMaker
    • Provide the selection road to the segment maker algorithm
  • The position and direction of the best MDT segment, together with other information, form the intersection is used as a starting point in the next step
  • The CSC is a separate region and trigger chambers cannot be used to help there. A segment in the CSC is used for further extrapolation.
• ...
• For the middle distance:
  • Perform fine extrapolation from best Inner result to each trigger chamber in list.
  • Look for hits in trigger chambers, make a segment (also in RPC) get position from it, and direction if the are enough hits or direction of extrapolated track if there are no enough hits.
• Correct η hits for r(φ of track) .
• Combine position and direction information from extrapolated track and trigger tracklet. We found that the trigger track is much better, and currently use it to extrapolate to MDT chambers.
• Perform fine extrapolation to each MDT chamber in list, using the best information available (trigger chamber or extrapolated ID track)
• Find digits (and tubes?) in road (correct endcap hits for r(φ)) prepare MdtDriftCircleOnTrack and send hits and road to Hough segment maker.
  • The position and direction of the MDT segment is used together with other info to do fine extrapolation to the next station.
• For Outer distance:
  • Perform fine extrapolation from best Middle result to each trigger chamber in list (barrel only).
  • Look for hits in trigger chambers, make a point in RPC, get position from it, and direction from extrapolated track (only 2 hits).
• Correct η hits for r(φ of track) .
• Combine position and direction information from extrapolated track and trigger position (check if this helps).
• Perform fine extrapolation to each MDT chamber in list, using the best information available (hits in RPC or previous best extrapolated)
• Find digits in road (correct endcap hits for r(φ)) prepare MdtDriftCircleOnTrack and send hits and road to Hough segment maker.
  • The position and direction of the MDT segment is used together with other info to do fine extrapolation to the next station.
• The result is hits and segments in each station.
• ANN to give quality factor
• Fit to get new track parameters (if high p_T).

Things we need in the ntuple (and therefore in class Candidate)

• ID p_T, position (η, φ) and direction (η, φ)
• Rough extrapolation position (η, φ) and direction (η, φ) for each distance/region
• Fine extrapolation position (η, φ) and direction (η, φ) for each station/technology
• Position (η, φ) and direction (η, φ) of segment for each station/technology
• Corrected position (η, φ) and direction (η, φ) for each station/technology
• Number of hits for each station/technology/readout direction
• List of hits η/φ
• Segment information quality, position (η, φ) and direction (η, φ) for each station/technology/readout direction

Todo

Study of performance (Natasha)

• Check for 4, 10, 100 GeV
• Distance from ID and TGC to inner MDT hits and to resulting segments.
• Distance from inner ID, TGC and MDT to middle TGC/RPC and MDT hits
• Best info to extrapolate to middle distance TGC
• Best info to extrapolate to middle distance MDT after TGC/RPC segment in middle
• Distance from middle ID, TGC/RPC and MDT to outer RPC and MDT hits
• Best info to extrapolate to outer distance RPC
• Best info to extrapolate to outer distance MDT after RPC segment in outer
• What quantities go into ANN

Study of ID tracking (Ofrit)

• Which inner tracking give the most efficiency and purity for ID muon tracks?
• Which inner tracking extrapolates best to muon spectrometer and gives the best final muon efficiency and purity?

Program evolution (Zvi)

Hough (Didi)

• Check Χ² calculation – removal of outliers
• Look at Χ² vs distance between multi layers
• Add in segment fit quality how many multi layers are included in segment
• Any news on CSC? Do we need to prepare anything in MuGirl?