• The files are stored on shift, so you have to log in to a na49i machine.
• Tracks can be visualized using a simple plotter called gnuplot (version 3.6 or 3.7).
  
  • PC Linux: only the old 3.5 version is installed, but you can have it using my compiled 3.7 version which is at ~fsikler/public/gnuplot/bin/gnuplot (make an alias to this).
  • Otherwise you can get the latest gnuplot 3.7 version from here.
  
  
  

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• Bin-by-bin track scan:
  The aim is to look at tracks with both positive and negative charges, in selected 5×5 bins in (p,p_T).
  Track selection: global rtracks with iflag=0 are used.
  
  The viewer call is given below.
  The 'event' field composition, just two examples:
  
  • 'pbpb/pos_p=3-6_pt=0.7-0.9'
    means positive, p between 3 and 6 GeV/c and p_T between 0.7 and 0.9 GeV/c.
    
  • 'pbpb/neg_p=10-15_pt=0.0-0.2'
    means negative, p between 10 and 15 GeV/c and p_T between 0.0 and 0.2 GeV/c.
  Hopefully we will have 100 tracks in each bin that can be accessed via the 'track' field by giving numbers between 0 and 99.
  
  

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• How to use it?
  Read the following thoroughly!
  • Login to a na49i
  • Type cd ~fsikler/public/ips/reform/view
  • Type ~fsikler/public/gnuplot/bin/gnuplot (look at machine dependencies here)
    
    

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  • The viewer call (after the prompt):
    gnuplot> call "plot" 'event' 'low z' 'high z' 'low x/y' 'high x/y' 'track' 'view'
    where
    • 'event': see above
    • 'track': track number 0-
      if there are no more tracks in the event the message
      "No tracks with sequential number ..." appears
      
    • 'view' : 0 for topview (z-x), 1 for sideview (z-y)
      Look at both views!
    • 'low and high x/y/z': determines the vertical and horizontal range for the plot, given in cm. Change this values to zoom in/out.
    Example:
    gnuplot> call "plot" 'pbpb/pos_p=3-6_pt=0.7-0.9' '-600' '800' '-400' '400' 1 0
    will display track 1 in the specified bin, in topview mode.
    Single and double quotes are important!
    
    

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  • Graphics
    

    Blue:	points belonging to the chosen track
    Red:	surrounding points of another tracks
    Green:	points of V0 candidate
    Lightblue:	unused points
    Open square:	fitted first point
    Green line:	result of the tracking without vertex constraint, line
    Purple line:	result of the tracking with vertex constraint, line
    Vertical line:	at target z, confidence limits on bx and by

    Labels - the above mentioned track numbers - are also plotted, centered on track pieces. They allow cross-checks with other tracks. The borders of the TPCs are indicated using straight lines (MTPCs are not rotated).
    Make the graphics window big enough in order to see the points.
    
    

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  • Printout
    After each call a line in the following format is printed and appears as a title in the graphics window:
    p=('px','py','pz') b=('bx','by') fit='fitted points' a/p=('vt1','vt2','mt') iflag='iflag' event='event'
    where
    • 'px','py','pz': track momentum components in GeV/c
    • 'bx','by': impact parameters at vertex->z in cm
    • 'a/p': actual over potential point ratios in the three TPCs in percent
      0% means: no actual points, although there are potential points
      -1% means: track cannot have points, i.e. there are no potential points
      
    • 'iflag': track iflag
    • 'event': event number
    Example:
    gnuplot> call "plot" 'pbpb/pos_p=3-6_pt=0.7-0.9' '-600' '800' '-400' '400' 1 0
    p=(-0.733 0.016 3.273) b=(0.56 -0.34) fit=167 a/p=(88%|55%|88%) iflag=0 event=1
    

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  • You can quit gnuplot by typing q or quit or exit
  
  
  

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• Reports
  25 bins will be distributed. Reports in written form are expected (mail) that will be displayed in a table: as an example you can look at the report-page of p+Pb here. At the end short summaries, remarks are also welcome.