BGV Simulation


The following operations can be performed within the simulation application (Gauss):
  • 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 examples

TODO: provide examples:

  • Read a simulated file
  • Visualize the BGV geometry and events with Panoramix
  • Generate and simulate beam-gas events with Gauss
  • Run a material scan job

Material budget


  • An LHCb ParticleGun tool is used to generate particles (instead of a pp generator like Hijing)
    • The particles should be "non-interacting", e.g. neutrinos, to avoid interactions and multiple scattering
    • An origin point is chosen (e.g. (0,0,0)) and many particles are generated with specific directions in order to cover the area of interest. The ParticleGun tool MaterialEval is designed for this purpose: one can generate particles in an x-y or eta-phi grid, with range and step size specified by the user
  • Scoring planes are introduced in the detector description geometry (DDDB)
  • The tool RadLengthColl looks when a Scoring plane is traversed and collects the information of interest
    • Scoring plane ID, x-y and eta-phi coordinates of the particles, accumulated interaction and radiation lengths, ...
    • The tool creates a ROOT NTuple containing these variables

Running a Gauss material scan job

  1. Obtain a local copy of the BGV XmlDDDB which you want to scan
    • E.g. /afs/
    • This package contains both the geometry (DDDB) and the option file needed to run the material scan job
  2. Enable the Scoring planes in the XmlDDDB which you want to scan
    • By default, the Scoring planes are there, but are commented-out
    • Need to uncomment the relevant lines in 3 files: DDDB/structure.xml, DDDB/geometry.xml and DDDB/BGV/geometry.xml
    • An example with enabled Scoring planes can be found in /afs/
  3. Run the Gauss job
    • XmlDDDB/options/
    • The main switches are:
      • nEvts: number of events. By default 1 particle is generated per event, so 62800 events are needed to scan the full plane (in the option file you can see the various settings for the grid and the step size)
      • MCP_ORIGIN_Z: z coordinate of the origin point of the generated particles (neutrinos) (a recent version of Sim/GaussTools is needed in order to use this feature; otherwise, only z=0 can be used; the feature is added in Gauss >v48r2?)
  4. Analyze the produced ROOT NTuple
  • A separate Gauss job must be run for each origin point. E.g. for the BGV one can study (0,0,0), (0,0,500), (0,0,1000), and (0,0,1500) -- see results below

Results (BGV XmlDDDB svn Rev. 92)

In total, 8 scoring planes are added in the BGV DDDB.
See the Panoramix view on the right.

Of biggest interest is Plane 7 which sits right behind
the far station. The Eta-Phi and X-Y maps shown below
refer to this plane.

Plot Type z_origin = 0 mm z_origin = 500 mm z_origin = 1000 mm z_origin = 1500 mm
Wide Eta range
Rad_Len vs Eta_averaged_over_phi
Eta - Phi Map
X - Y Map
Zoomed Eta range
Rad_Len vs Eta_averaged_over_phi
Eta - Phi Map
X - Y Map

Topic attachments
I Attachment History Action Size Date Who Comment
PNGpng bgv_scoring_planes_withID.png r1 manage 17.3 K 2015-07-14 - 20:18 PlamenHopchev  
PNGpng radMap_EtaPhi_z0_ID7.png r1 manage 157.6 K 2015-07-14 - 19:41 PlamenHopchev  
PNGpng radMap_EtaPhi_z0_ID7_zoom.png r1 manage 134.9 K 2015-07-14 - 20:08 PlamenHopchev  
PNGpng radMap_EtaPhi_z1000_ID7.png r1 manage 139.2 K 2015-07-14 - 19:41 PlamenHopchev  
PNGpng radMap_EtaPhi_z1000_ID7_zoom.png r1 manage 146.8 K 2015-07-14 - 20:08 PlamenHopchev  
PNGpng radMap_EtaPhi_z1500_ID7.png r1 manage 131.1 K 2015-07-14 - 19:41 PlamenHopchev  
PNGpng radMap_EtaPhi_z1500_ID7_zoom.png r1 manage 148.1 K 2015-07-14 - 20:08 PlamenHopchev  
PNGpng radMap_EtaPhi_z500_ID7.png r1 manage 154.1 K 2015-07-14 - 19:41 PlamenHopchev  
PNGpng radMap_EtaPhi_z500_ID7_zoom.png r1 manage 148.3 K 2015-07-14 - 20:08 PlamenHopchev  
PNGpng radMap_XY_z0_ID7.png r1 manage 248.3 K 2015-07-14 - 19:41 PlamenHopchev  
PNGpng radMap_XY_z0_ID7_zoom.png r1 manage 179.1 K 2015-07-14 - 20:08 PlamenHopchev  
PNGpng radMap_XY_z1000_ID7.png r1 manage 229.7 K 2015-07-14 - 19:41 PlamenHopchev  
PNGpng radMap_XY_z1000_ID7_zoom.png r1 manage 246.7 K 2015-07-14 - 20:08 PlamenHopchev  
PNGpng radMap_XY_z1500_ID7.png r1 manage 205.3 K 2015-07-14 - 19:59 PlamenHopchev  
PNGpng radMap_XY_z1500_ID7_zoom.png r1 manage 231.0 K 2015-07-14 - 20:08 PlamenHopchev  
PNGpng radMap_XY_z500_ID7.png r1 manage 253.4 K 2015-07-14 - 19:41 PlamenHopchev  
PNGpng radMap_XY_z500_ID7_zoom.png r1 manage 242.5 K 2015-07-14 - 20:08 PlamenHopchev  
PNGpng rad_eta_per_plane_z0.png r1 manage 98.4 K 2015-07-14 - 19:37 PlamenHopchev  
PNGpng rad_eta_per_plane_z0_zoom.png r1 manage 101.2 K 2015-07-14 - 20:08 PlamenHopchev  
PNGpng rad_eta_per_plane_z1000.png r1 manage 102.9 K 2015-07-14 - 19:41 PlamenHopchev  
PNGpng rad_eta_per_plane_z1000_zoom.png r1 manage 100.3 K 2015-07-14 - 20:08 PlamenHopchev  
PNGpng rad_eta_per_plane_z1500.png r1 manage 98.0 K 2015-07-14 - 19:41 PlamenHopchev  
PNGpng rad_eta_per_plane_z1500_zoom.png r1 manage 103.9 K 2015-07-14 - 20:08 PlamenHopchev  
PNGpng rad_eta_per_plane_z500.png r1 manage 104.8 K 2015-07-14 - 19:41 PlamenHopchev  
PNGpng rad_eta_per_plane_z500_zoom.png r1 manage 102.6 K 2015-07-14 - 20:08 PlamenHopchev  
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