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WP1 F2F meeting

Muirhead Tower (R21): room 715 (University of Birmingham)

Muirhead Tower (R21): room 715

University of Birmingham


For those who cannot attend in person: we will provide connection to the regular WP1 zoom link: https://cern.zoom.us/j/69495072023?pwd=MGxCMjZKakJQbnBsTlJ0VldENm5GZz09

Zoom meeting ID: 69495072023

Host: Laura Gonella

Passcode: 26244277



Layout (SVT with emphasis on OB) - James

L4 will stay as is but with more overlap to move to 420 mm radius.

L3 works well really just with 6 RSU LAS for overlap, integration, stave and FPC design. With 5-RSU LAS the layer moves at a much smaller radius with large overlap and thus more material. We do not want this.

Needed: someone to implement sensors dead area and overlap, plus castellated structure in simulations.

Integration (SVT with emphasis on OB) - Georg

Needed: someone to look into pressure regulators and distribution of air to the layers and calculate flow channels.

Routing of FPC of L4 to RDO needs careful study. FPC to be routed through support structure. 

Ancillary chip and LAS - Roy

The 1.8V problem is not a problem anymore. Serialiser powered by SLDO rather than internal MOSAIX LDO.

GA and GD at 1.3V, services 1.32V. Check with Iain that serialiser is at 1.2V and power burned because of lower voltage wrt GA, GD and services.

R3 is external on the FPC.

Powering scheme - James

Questions on redundancy and reliability of the chain

SLDO Progress - Roy

Modularity - Marcello

Discussing a support structure for LAS + ancillary chip. Make it an electrical unit that can be built and tested before loading on the stave.


  • Kapton could be used as material for the support. Electrically insulating, thermally conductive.
  • AncASIC on the stave needs to be in good thermal contact with the structure that is bent. Do we need to bend this chip too? Can the structure have a flat part where the AncASIC is? 
  • AncASIC could sit on the structure with the bridge FPC on top.
  • Tabbonding or wire bonding for connection between AncASIC or FPC? Depends on how much goes through one pad. Tab bonding better for high current (such as SLDO pads?). Check with designers how much current per pad in AncASIC)
  • Can we tab bond bridge FPC to main FPC on stave? Otherwise wire bond.
  • The main FPC runs on the sides of the stave structure.

Conclusion of brainstorming: bond AncASICs to bridge FPC (tab or wires) and test on dedicated board; mount 2 LAS to Kapton frame; add bridge FPC with AncASICs to Kapton frame; bond LAS to bridge FPC; test; load on stave; bond bridge FPC to main FPC.

Stave model and mechanical FEA - Adam (RAL), Stave CFD and thermal FEA - Stephanie (Oxford)

Stephanie's simulation done with with 5 m/s. No AncASIC yet, LAC power for max 25 not max 45, at 5 m/s, deltaT of 27C. We will need higher speed of air flow, 20 m/s? We will have to see if the stave can take it. Adam makes the point that the bend curvature helps us to deal with pressure.

Stave FPC integration and electrical connection - Marcello (Daresbury)

Overview of latest on the FPC design.
Had question on the latest voltage requirements for the SLDOs (advised to check with Iain/Roy).

Preference is to have multiple manufactures available for the FPC fabrication (in case of any issues, we have a back-up manufacturer). Can we have 2 manufacturers make the same design?
Looking to have 2 layer FPCs, probably need to change the stack-up to have aluminium tracks on both top and bottom sealed off (current designs work with top tracks open to the air).

Common FPC design is currently 5 x 300 mm (stack-up gives a comparable radiation length to 50 um of silicon).

A prototype FPC is to be made by the summer. This is to include a common FPC and bridge FPCs, to check data transmission with the interconnects of these two FPCs. Testing is likely to be done as a collaboration between Daresbury and Uni of Oxford.

From the discussion: (Jian) With the extra thick metal layers in the current sensor design, the equivalent silicon thickness (in terms of radiation length) is not 66 um (not 50 um).

Stave assembly procedures and tooling - Tim Jones (presented by Georg)

Liverpool to look at the laminate carbon fibre wanted to the OB staves (based on K13CTU).

Showed some considerations on the carbon fibre curing (some preferences and hopes).

Also demonstrated a stave assembly process (might need to change with the carbon fibre I-beam shown by Adam).

Started to look at the tooling and prototyping options needed.

Support cones and stave-cone interfaces – Ken Davies (presented by Georg)

James, Adam and Ken to converse and establish a base-line design and dimensions of the staves and barrel structure.



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