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Common Wire Tracker Digitisation

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42/R-032 (CERN)

42/R-032

CERN

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Common Wire Tracker Digitisation
Zoom Meeting ID
66054475206
Host
Andreas Loeschcke Centeno
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Quick recap

The team reviewed Muhammad's simulation tool for drift chambers and its potential adaptation for straw trackers, discussing various parameters and requirements for implementation. They explored the implementation of waveform propagation functionality and digitizer omponents, including noise models and integration with conformal tracking systems. The team also discussed code structure improvements, including generalizing the DCH info class and simplifying cell ID nomenclature, while planning next steps for documentation and future meetings.

Next steps

  • Muhammad: Generate a separate file for cluster generation that can be used for any gas mixture (factorisation of code)
  • Muhammad: Open a pull request on K4RecTracker GitHub (mark as draft) within one week to allow code review and feedback
  • TBD: Update probabilities for cluster density and cluster size distribution if using gas other than helium isobutane
  • TBD: Generate lookup table for drift time distribution according to Straw Tracker cell geometry
  • Andreas: Verify that storing drift time to distance relation and noise distributions in root file is the most efficient way
  • TBD: Recalculate noise amplitude and template according to test beam data if using colored noise for Straw Tracker
  • Stefano: Perform more thorough validation of the wire tracker info implementation
  • Stefano: Check detailed logs to verify that DCH geometry doesn't change with the new implementation
  • Stefano/Andreas: Update the digitizer to work with the new wire tracker info structure in K4Geo
  • Stefano: Store number of cells directly instead of number of wires (N_wires) in the layer info structure
  • Stefano: Store stereo angle directly in layer info instead of calculating it each time
  • Stefano: Remove calculation of average cell Z0 and use sensitive wire Z0 directly
  • Stefano: Simplify layer info structure by removing redundant parameters that can be calculated from other values
  • Andreas: Review Stefano's pull request on K4Geo for wire tracker info implementation
  • Andreas: Add comments to the pull request based on meeting discussion
  • TBD: Open pull request to remove current DCH info from DD4hep repository once new implementation is validated
  • Brookhaven team: Test the conformal tracking with the new digitizer output once code is publicly available
  • Team: Determine current gas mixture used in Straw Tracker geometry (helium-based or argon-based)

Summary

Drift Chamber Simulation Tool Presentation

Muhammad presented a simulation tool for drift chambers that can be adapted for straw trackers. He explained that several components of the simulation are gas-dependent, including cluster density, gas gain, and drift time modeling. For the straw tracker implementation, Muhammad identified key requirements including updating the geometry-specific lookup tables and adjusting electronics parameters like matching resistance and tube impedance. The tool can handle different noise models, with colored noise requiring specific data, while white noise from drift chamber test beam provides a simple baseline.

Straw Tracker Digitizer Review Meeting

The team reviewed Muhammad's presentation on the digitizer for the Star Tracker, which creates full waveforms rather than just counting clusters. They discussed the parameters for calculating ionization in gas, including the number of clusters per centimeter and the number of electrons per cluster, which currently use fixed values for helium but could be adapted for different gas mixtures. The team clarified that these values are based on standard conditions and can be adjusted for different gas types, with Muhammad noting that experimental results for specific gas mixtures would be needed for future implementation.

Drift Chamber Implementation Discussion

The team discussed implementing drift chamber functionality for straw tubes, focusing on charge drift mechanisms and lookup tables. Muhammad explained that the current implementation uses a lookup table stored in a root file to interpolate drift times based on hit positions, though Andreas suggested this might not be the most efficient approach, to be checked. The team confirmed that many parameters including Gaudi properties and shape parameters can be easily modified without significant code changes, and Muhammad noted that the implementation for waveforms would be similar to existing code.

Waveform Propagation Implementation Discussion

The team discussed the implementation of waveform propagation functionality, which requires Z-position and stereo angle data from the straw tracker. They reviewed electronic slides showing noise frequency data from test beam measurements, which will be converted from frequency to time domain using inverse fast Fourier transform. 

Testing the code

The team discussed integrating this code with conformal tracking, though it is currently in a local repository and needs to be made publicly available before testing with conformal tracking can begin. Muhammad mentioned he needs to finalise the factorisation of code.

Ang expressed interest from the Brookhaven team to test the code for the straw tube tracker.

GitHub K4RecTracker Updates

Andreas suggested that Muhammad open a pull request on the GitHub k4RecTracker as a draft to receive targeted feedback on his code. Stefano presented a summary of the work done to generalize the DCH info class into a wire tracker info class that can be shared between drift chambers and straw tube trackers. The new class structure was tested and compiles correctly, but further validation and updates to the digitizer are needed for complete functionality.

Cell Geometry Implementation Discussion

Gianfranco and the room discussed the implementation of cell geometry in their code, particularly regarding the height and width of cells in a drift chamber, which are redundant for the straw tubes. They discussed the redundancy for the drift chamber, given the square cell design, and Stefano mentioning that the current drift chamber geometry asserts equality between cell width and height.

They explored alternative options for handling layer information and inheritance, considering both pointer-based and alternative approaches like unique pointers, in order to be able to store different information in the database for the drift chamber and straw tubes. 

The conversation also touched on the possibility of accepting to store the redundant information for geometry construction, with Andreas suggesting that storing height and width as separate values for the straw tubes might not significantly impact performance given the relatively small

number of layers.

Cell ID Nomenclature Simplification Discussion

The team discussed simplifying the cell ID nomenclature and code structure for drift chambers and straw tubes. They agreed to store the N cells instead of N wires, remove unnecessary calculations for stereo angles, and potentially eliminate redundant wire radius measurements. Andreas gave the green-light to Stefano regarding the simplification of some of the legacy code, with Stefano mentioning unnecessary calculations and confusing behaviour for the retrieving the stereo angle.

Andreas requested that these changes be documented in the pull request, and they scheduled the next meeting for two weeks from now, though Andreas noted potential conflicts with a tutorial on Thursday evening.

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