Sci Fi Simulation and Reconstruction Status

1. Sci Fi Simulation and Reconstruction Status M.Ellis/C.Rogers Wednesday 31st March 2004

2. 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: • 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

3. 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.

4. G4MICE: 8.7 Light Yield (Cosmic & G4MICE) Tracker Prototype: 8.9

5. 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.

6. 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.

7. 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.

8. Momentum Resolution with first version of dE/dx

9. 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.

10. 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 clean-up 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.