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BGI Regular Meeting

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864/2-B14 - SALLE J.B.ADAMS (CERN)

864/2-B14 - SALLE J.B.ADAMS

CERN

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BGI Regular Meeting
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63808180348
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James Storey
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Present

Present: Gunn, Hampus, James, Justus, Juri (Zoom), Lukas, Mark, William, Wilfried

1) HL-LHC BGI — Mechanics / assembly / simulations

1.1 Review of previous actions (from last meeting)

  • Mechanical model update (revised “cathode layer”) shared for simulation work (by Michaela).

  • Attachment technology tests (glue / “stay-stick”) progressing: discussion with brazing specialists indicates brazing approaches are feasible; a concrete test proposal is to be prepared and submitted.

  • Plan to involve Polymer Lab (MSCM/Magnets) for advice and faster preparation of glue samples for vacuum/outgassing tests (parallel activity).

  • Sensor→ASIC bonding: feasibility to flip-chip bonding with the ASIC already attached to ceramic to be determined, subject to temperature constraints (~220–240 °C limit range discussed); fit on bonding machine to be confirmed.

  • Ceramic PCB: before ordering, an outgassing test at VSC is needed/ongoing; concern noted about multi-layer ceramic processes and binders/adhesives between layers.

1.2 Outgassing / cleaning approach

  • Agreed it is sensible to clean the sample before VSC outgassing tests (since cleaning will likely be needed anyway), while acknowledging solvent entrapment risk; VSC can measure before/after bake to assess behaviour.

1.3 HV/mechanics integration constraints (magnet + feedthrough region)

  • Need to confirm available transverse space around the BGI for:

    • PCB + electronics side

    • HV feedthrough side (including allowance for impedance matching components)

  • Dominique’s magnet design is close to final; request from magnet side is to confirm required envelope ASAP, as only a few mm margin remains (no expectation of additional space beyond the current compromise).

  • Particular concern: minimum bending radius of the ~40 kV proprietary HV cable must be respected; if too large, alternatives (e.g., elbow connector / different routing) may be required.

1.4 Presentation & discussion: VIPM + CST misalignment sensitivity (G. Khatri)

  • Method recap: CST 3D field map from the current mechanical design is used in Virtual IPM simulations; baseline assumes uniform B field By = 0.6 T and CST-derived E-field, with no misalignment. The baseline target is relative sigma error < 2%.

  • Misalignment study used a rectangle approximation (x,y,z) = (140, 140, 220) mm to map linear offsets to angular errors.

  • Simulated independent angular misalignments (pitch/yaw/roll; θx, θy, θz) and observed that:

    • θx (tilt around x) produces the most concerning effect, primarily a systematic profile shift (and potential asymmetry/distortion), driven by E×B drift.

    • θz effects are largely “washed out” by integration along z (beam axis) in the presented plots; θy appeared less critical in the current scans, but needs confirmation when considering clustering/pixel effects and full reconstruction.

  • Alignment baseline: discussion referenced ~200 µm as an achievable survey/alignment scale; preliminary results suggest this may be acceptable, but the “devil is in the details” (internal alignment between cathode/detector, repeatability when swapping instrument modules, etc.).

  • Point raised: for the first instrument, a full metrology campaign could be valuable to establish realistic as-built tolerances and feed back to both mechanics and reconstruction.

2) PS & SPS BGI — DAQ / controls / software status

2.1 Follow-up from two weeks ago

  • Joint regular meetings with OP established.

  • Offline analysis library scope (incl. ML background subtraction / denoising): acknowledged as existing but not currently on the critical path.

  • Structured proposal for LS3 interventions (James) still pending; to be produced by end of month.

2.2 Slow control status

  • Slow-control functionality for Timepix (setting and reading back configs/masks/settings) is implemented in principle, but not yet validated on real hardware.

  • Overall schedule reported as ~2 weeks behind, mainly due to unforeseen work/bugs; deliverable dates were considered still recoverable due to planned schedule margin.

  • Current end-to-end capabilities (today):

    • Can set settings and observe detector response; can read back configuration (theory implemented, hardware validation pending).

    • Can read generated/fake events and store to files.

    • Real detector data path and real slow-control feedback require hardware debugging/testing next.

  • Hardware available for tests: ~5 Timepix devices in the lab, currently a subset connected; PS/SPS backend integration is available “in theory” pending flashing firmware/software. LHC backend is not yet in place.

2.3 Operational considerations

  • Discussion on whether to operate V4 during early beam/scrubbing: consensus leaned toward avoiding unnecessary risk until V5 is validated; however, once basic safety checks are complete, syncing/status checks could be done non-invasively on operational devices.

 
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