Transcript Sci Fi Simulation and Reconstruction Status M.Ellis/C.Rogers Wednesday 31st March 2004 Status and Developments • Pattern recognition follows the scheme: – Build clusters of hits.

Sci Fi Simulation and
Reconstruction Status
M.Ellis/C.Rogers
Wednesday 31st March 2004
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Status and Developments
• Pattern recognition follows the scheme:
– Build clusters of hits (as for cosmic ray test)
– Build space points (triplets only at the moment)
– Build tracks (find best track in each tracker).
• Ongoing development in the following areas:
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Reproduction of cosmic test performance
Modification of geometry/etc to match latest design.
Treatment of dE/dx in Kalman fit
Improved Pattern Recognition performance in presence
of high background
– General code cleanup
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Matching Cosmic Test Results
• Light Yield in simulation is now the same as that
measured in the 5000 ppm 3HF fibre, as this is the
worst case.
• Hit finding cut used is the same as for the cosmic
analysis – 2 Photo Electrons.
• Simulation does not include non-linearity of
VLPCs above 15 PE, however this should not be
an issue, as a hit is anything above 2 PE, and the
actual signal is not used.
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Light Yield (Cosmic & G4MICE)
G4MICE: 8.7
Tracker Prototype: 8.9
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Modification of Geometry
• Fibre pitch has been increased from 420 to 427
mm.
• Spacing of stations in Z needs to be altered due to
physical constraints caused by the waveguides,
however these distances have not yet been
optimised, so this study still needs to be
performed.
• Need to confirm exact thickness of material and
radiation length in simulation and reconstruction
descriptions.
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dE/dx in Kalman
• New version of the Kalman package has
been provided that includes dE/dx in the
propagation of states.
• First version of the tracking code in
G4MICE using this is currently undergoing
testing.
• Hope to release new Kalman and
corresponding Sci Fi code by the end of the
Software Workshop.
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Future Improved Performance
• Under very high backgrounds, the Pattern
Recognition still works well, but slowly due to the
number of combinations tested.
• Currently modifying the pattern recognition to
remove bad combinations of hits/points and
outliers as early as possible.
• In addition, code has a lot of copies (objects being
passed by copy, rather than reference or pointer) –
this is being cleaned up as part of the overall
design iteration process.
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Momentum Resolution with
first version of dE/dx
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General Code Clean-up
• Due to hurried nature of development over the
past 12-18 months, a lot of classes are less
efficient than they could be, with wasteful loops,
copies, etc.
• Design Iteration process for the Sci Fi code will
include a complete look at the classes needed for
the Sci Fi and how they should interact.
• This clean-up process has already been started in
parallel with the higher level studies.
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Conclusions
• Progress is being made, but slowly.
• Performace of tracker in cosmic ray test stand has
been propagated to the simulation.
• First version of the track fit with dE/dx is now
running and being debugged.
• Further improvements in physics performance and
CPU/memory use expected following code cleanup and design iteration.
• As is true for any aspect of the software effort,
anyone who wants to help is very welcome, please
talk to Yagmur, or the relevant package manager.
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