BGV Detector

Links to Topics:

      Arrow blue right SciFi Modules

      Arrow blue right Installation & Alignment

      Arrow blue right Cooling

      Arrow blue right L0 Trigger

Engineering Drawings:

Naming Conventions for Axes and Modules

The Demo BGV has 2 stations ("near" and "far" to the exit window).
Each station is made of 4 SciFi modules. The module layout is described below.

The BGV coordinate frame is right-handed, with +z along the beam2 direction.
The x axis points towards the center of the LHC ring.

The module ID arrangement can be seen here.

In each module, there are 2048 SiPM channels (0 to 2047) starting on the left of the x-plane (view from the face, cut-out at the bottom right). Channel 1024 (first on the u-plane) is on the left side of the u-plane (view from the face, cut-out at the bottom left). The refrigerant flows in the direction channel 0 to 1023 on the x-plane just as the dry gas. On the u-plane, the refrigerant and the dry gas flow in the direction 1024 to 2047.

pdf version

pdf version

Design Considerations

Here, a brief description is given of the design considerations and the choices made for the BGV beam profile monitor.

The details of the systematic studies performed at the start of the BGV project can be found in Massi's and Plamen's slides in the first few BGV meetings. In particular:

Essential BGV design considerations

Rate and charged-particle multiplicity of the beam-gas interactions
  • Determined by the properties of the "gas target"
  • The BGV will use Neon (possibly test Argon) at nominal pressure 6e-8 mbar
  • The figures on the right show the charged particle multiplicities of events generated with the LHCb SW, using the Hijing generator. The gas target is Oxygen (results for Neon are very close) and the beam energy is 450 or 7000 GeV
Polar angle acceptance
  • Determines what fraction of the produced particles can be detected
  • The two top figures on the right show the pseudorapidity distributions of the charged particles produced in p-Oxygen collisions at 450 and 7000 GeV (Hijing simulation). For convenience, the η=3 and η=5 marks are shown (the actual BGV demonstrator acceptance is smaller)
  • The dimensions of the exit window of the BGV gas injection chamber determine the acceptance. In the case of the BGV demonstrator:
    • The inner diameter is limited by aperture. Determines η_max
    • The outer diameter is limited by RF heating and physical space (distance between the two LHC vacuum chambers). Determines η_min
  • The experience with the BGV demonstrator will show if any of the imposed requirements can be reconsidered
  • The two bottom figures on the right show:
    • The center and width of the pseudorapidity distributions of different gas targets, at beam energy 450 and 7000 GeV
    • The polar angle acceptance of a chamber with exit window with r_min=23 mm, r_max=130 mm as function of the longitudinal distance between the collision point and the exit window. The actual dimensions of the BGV demonstrator window are r_min = 26.9 mm, r_max = 106 mm, length ≈ 2 m


Example of the BGV layout
  • Sketch of BGV acceptance requirement used in the early design studies (before the implementation studies)
  • The red lines indicate the polar angle acceptance limits corresponding to η_min = 3 and η_max = 5 (considered are interactions occurring at 3 different longitudinal positions)

Material budget

  • Multiple scattering occurs in any material traversed by the beam-gas collision products
  • The multiple scattering changes the trajectory of the particles and therefore needs to be minimized (considering also the other factors influencing the track reconstruction accuracy)
  • For the case of the BGV demonstrator, there are two elements that contribute to the material budget for particles in the detector acceptance: the chamber exit window and the detector modules
  • An estimate of the SciFi module material budget can be found here
  • A detailed description of the material budget in the BGV SW Simulation can be found here
Topic attachments
I Attachment History Action Size Date Who Comment
PNGpng Angular_acceptance_exit_window_130mm.png r1 manage 77.8 K 2015-07-14 - 15:13 PlamenHopchev  
PDFpdf BGV_DETECTEUR_OLIVIER_01.pdf r1 manage 39.6 K 2015-07-06 - 16:46 UnknownUser  
PNGpng BGV_DETECTEUR_OLIVIER_01.png r1 manage 11.8 K 2015-07-06 - 16:49 UnknownUser  
PDFpdf BGV_DETECTEUR_OLIVIER_02.pdf r1 manage 56.8 K 2015-04-16 - 11:03 UnknownUser  
PNGpng BGV_DETECTEUR_OLIVIER_02.png r1 manage 17.6 K 2015-04-16 - 11:14 UnknownUser  
PNGpng ChargedPartMult_hi_8_450.png r1 manage 87.0 K 2015-07-14 - 15:13 PlamenHopchev  
PNGpng ChargedPartMult_hi_8_7000.png r1 manage 86.3 K 2015-07-14 - 15:13 PlamenHopchev  
PNGpng Pseudorap_Center_and_Width.png r1 manage 84.5 K 2015-07-14 - 15:13 PlamenHopchev  
PNGpng Pseudorap_hi_8_450.png r1 manage 85.8 K 2015-07-14 - 15:13 PlamenHopchev  
PNGpng Pseudorap_hi_8_7000.png r1 manage 65.3 K 2015-07-14 - 15:13 PlamenHopchev  
PNGpng bgvsketch.png r1 manage 150.6 K 2013-04-26 - 15:22 MassiFL sketch of BGV acceptance requirement (polar angle and longitudinal extent)
PNGpng modules_naming_convention.png r1 manage 2003.6 K 2015-09-28 - 12:21 PlamenHopchev  
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Topic revision: r26 - 2015-11-27 - unknown
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