ALICE TPC

1
ALICE TPC
Marian Ivanov GSI - ALICE
2
Update

• faster digitization - factor 30
• region of interest introduced (Jiri presentation)
• improvement in cross-talk between pad-rows -
  decreasing of the occupancy (see Jiri talk) -
  increasing of the efficiency
• New pad geometry -different pad size for
  outermost sectors introduced (1.5x0.6 and 1.0x0.6
  cm) - (again decreasing of efficiency -) )

3
Digitization speeding up region of interest

• For p-p run - noise taken from noise table - not
  gRandom-gtGaus for each channel generated 15
  minutes -gt7
• not range checking for each update of matrix -
  AliTPCFastMatrix used - row pointer iterator -gt 3
  minutes
• region of interest - important for the merging -
  with few interesting sectors - digitization time
  3s

4
Led -Led

• Used lookup table for the response calculation -
  instead of interpolation
• fast unchecked matrix access
• speeding factor 30

5
Cross-talk update

• Occupancy decreased
• AliTPComparison results - full Hijing
• no secondaries

6
Conclusion

• TPC microscopic simulator developed as a part of
  the AliRoot framework
• TPC performance optimized using MC simulator
• optimized TPC performance - fulfill requirements
  

7
Track debug info

• Needed for
• tracking performance evaluation
• influence of the material to the momentum
  resolution and PID ?
• ?
• How is it done - current - temporary solution
• TPC
• momentum at the entrance of the TPC stored as hit
  with 0 charge in track hits
• TRD
• momentum at the entrance of each TRD chamber in
  track hits

8
Track debug info

• Disantvantage
• to find track info - needed to process huge
  track hits tree 0.7 Gby - non homogenous data -
  bad compression factor
• difficult to find this information
• needed separate structure to store info

9
Track debug info

• When to generate it ? ?