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BGI Regular Meeting
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Europe/Zurich
864/2-B14 - SALLE J.B.ADAMS (CERN)
BGI Regular Meeting
Present: Gunn, Hampus, James, Justus, Juri, Lauren, Lukas, Mark, Ray, Steen, William, Wilfried
PS & SPS BGI
Overall progress was reported as broadly on track, with only a minor delay of around one week and no major showstoppers identified. The full data chain from the acquisition system through to the FESA class(es) is now essentially functional. With beam already available in the PS, planning to start using the system with real beam imminently. The OP GUI work is progressing, with fake data already available to OP, although it has not yet been actively used. It was agreed that regular joint meetings with OP (and SPS/PS stakeholders) should now be kick-started, and that ABP should also be invited to ensure good information flow.
The need to anticipate LS3 interventions for PS/SPS was highlighted, particularly regarding vacuum and RF shield modifications. For SPS, if the vertical plane with a more open RF shield proves successful, applying the same approach to the horizontal plane was seen as a likely next step, though this will require a well-structured proposal and coordination with vacuum and shutdown planning. The discussion also raised the requirement to provide raw data access and an offline analysis library, including potential ML-based beam-loss removal algorithms. It was agreed that the scope and specification of this library have not yet been clearly defined and should be addressed explicitly.
HL-LHC BGI
A key mechanical update concerned the re-orientation of the cathode insulators to ease mechanical integration by avoiding overhang issues inside the curved tank. This change was generally seen as acceptable, with only minor impacts on volume and capacitance. Ongoing work includes testing attachment options for the Timepix4 detector (glue, Staystik, and brazing), revisiting thermal simulations with updated power estimates, and refining impedance-related design features such as added shoulders. Stainless steel is currently favoured over ceramic for the cathode from an impedance perspective, although ceramic remains a possible alternative.
Broader integration topics were also discussed. Magnet design for HL-LHC BGI is progressing towards procurement, with parallel work ongoing on girder design, alignment philosophy, and space constraints (including provision for electronics racks). Alignment simulations are being prepared to define acceptable tolerances and to confirm the strategy of aligning the tank rather than re-aligning the instrument after each exchange. Finally, the need for early electronics prototyping and vacuum/thermal testing was emphasised. Rather than a full “prototype” instrument, the priority is to validate pixel detector electronics under vacuum and thermal load using a simplified or off-the-shelf vacuum test setup, ahead of final MME production timelines.
Summary of Actions
PS & SPS BGI
- Start regular joint meetings with OP for PS/SPS BGI; extend invitations to ABP and other relevant stakeholders - Hampus, before next meeting
- Clarify and define the scope/specification of the offline analysis library, including whether ML-based beam-loss removal should be included - tbd.
- Prepare a structured proposal for LS3 PS/SPS interventions, especially regarding RF shield modifications and vacuum work - James, by 28/02/2026
HL-LHC BGI
- Update HL-LHC BGI mechanical model to reflect the revised cathode insulator orientation - Lauren
- Proceed with attachment technology tests (glue first, then Staystik; brazing as preferred option if feasible), including radiation-hardness considerations - Lauren, William
- Contact EP-DT expertise on radiation-hard glues to assess suitability of candidate materials - James, before next meeting
- Provide updated estimate of Timepix4 power load for thermal simulations - Hampus, before next meeting
- Update thermal simulations using revised power estimates and feed results into mechanical and PCB design discussions - Lauren
- Prepare alignment tolerance simulations and present acceptable misalignment limits at the next meeting - Gunn, for next meeting
- Develop a plan for early electronics vacuum/thermal testing, using a simplified or existing vacuum test setup, decoupled from final tank production - tbd.
- Coordinate with magnet and girder design teams to ensure space, alignment, and integration constraints (including electronics racks) are captured early - William
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