Simulation

Overview

• Generation of the primary beam-gas interaction
  • A third-party generator (e.g. Hijing) is used
• Propagation and interaction of the beam-gas collision products with the material defined in the BGV geometry
  • A dedicated geometry is developed that defines the relevant infrastructure, vacuum chambers and BGV detector components
  • The MCHits, i.e. the particles' energy deposit inside the sensitive detector elements, can be stored in the produced .sim file
  • The "digitization" step converts the MCHits into a pair <SciFiChannelID, Energy>, allowing the simulated data to be represented in a way identical to the raw data coming from the SciFi detectors. The MC information (e.g. particles and vertices) can be kept or not in the produced simulated files.

Usage and Examples

• An example GaudiPython script is provided
  • Reads a .sim file located on castor
  • Creates a root ntuple (aka TTree) with some info (just an example). The ntuple creation and filling is not mandatory (it is not so useful for simple checks)
• To run it:
  • source /afs/cern.ch/work/p/phopchev/public/LHCbSW/BGVLoginScript.sh
  • SetupProject Panoramix v22r0
  • python -i /afs/cern.ch/work/p/phopchev/public/BGVExamples/pano_read_sim_make_ntuple.py

Read the root ntuple produced by the script above

• An example PyRoot script is provided
  • Lists the ntuple branches and draws a histogram
  • Two plotting approaches are demonstrated: PyRoot and matplotlib. In both cases the root TTree::Draw method is used to obtain (and possibly apply a cut on) the values of interest
• To run it:
  • source /afs/cern.ch/work/p/phopchev/public/LHCbSW/BGVLoginScript.sh
  • SetupProject Panoramix v22r0
  • python -i /afs/cern.ch/work/p/phopchev/public/BGVExamples/read_ntuple.py

Visualize the BGV geometry and events with Panoramix

• A shell script is provided that encapsulates the command to be executed
  • The input event and geometry files are specified as arguments
  • It is the user's responsibility to provide consistent event and geometry files
  • Don't mind the FATAL and ERROR messages from VeloClusterPosition and MeasurementProvider (looks like we need to fix hard-coded statements in the LHCb code)
• To run it:
  • source /afs/cern.ch/work/p/phopchev/public/LHCbSW/BGVLoginScript.sh
  • SetupProject Panoramix v22r0
  • . /afs/cern.ch/work/p/phopchev/public/BGVExamples/pano_run_vis.sh
  • If you wish to visualize events (particles, vertices, etc.) you need to read at least 1 event from the input file
    • Use the "arrow" button in the panoramix menu, or type appMgr.run(1) in the python prompt

Generate and simulate beam-gas events with Gauss

• To be completed