Comments on Engineering talk by A. Catinaccio at Inner Tracker Engineering Meeting CERN ) Fixed length barrel layout drawing by C. Bault (Strawman 08): shows the end barrel at Z = 1200 with EC start at Z = 1360 ie gap for pixel and barrel services is 160 Too small in region of outer barrels at R max. 2)Radius of layers not very clear on drawing but gap seems to be between R = 960 (outer R of EC discs) and R = 1033 (inner R of ‘outer cylinder’) ie gap for EC services, Pixel services and Barrel services is 73 Although services are spread out at this R, they will need support structures and covers – so a gap of 73 is far too small. There is a known clash with outermost barrel layer radius R = Action: This drawing needs a more realistic representation of services occupancy before it is too late! At present they are still depicted as very thin cables with plenty of surplus space in the gaps. We should get the drawing file and fill in the gaps and indicate clashes whilst services are still in the conceptual stage….. FIXED LENGTH BARREL LAYOUT

Comments on Engineering talk by A. Catinaccio at Inner Tracker Engineering Meeting CERN ) No pixel services are shown yet, so barrel services are spread out in phi. Although old services will be removed from the cryostat, enabling the design of a new layout for services channels, space has to be allocated to pixel services which may require specific routing in phi. 2) Cooling: Concept of circumferential manifolding is similar to a very early idea for the current SCT barrel which was modelled at UCL but rejected in favour of a small two-pipe manifold for exhaust pipes as part of the 4 row cooling unit. The circumferential manifolds here occupy an extended flange for support – good for access to other layers but all other services have to route over layers. Is circumferential mass and ‘bunching’ at 45 degs better than single pipes spread out over barrel end? Access to VCRs looks good if all fibres and cables disconnected first - but would still present strain on pipe. 3) SMC: Uses up module space at end of barrels – better as an extension in phi or outside on barrel end. Fragile fibres loop out from barrel end and join very substantial power-cables bunched in sleeving. Usually this is avoided - as fibres could be damaged if big cable is moved during installation. SMC fibre connector blocks take up a lot of space – clash with adjacent module? End of Stave Services: (applies to both ‘stave’ and ‘non-stave’ concepts)

Comments on Engineering talk by A. Catinaccio at Inner Tracker Engineering Meeting CERN ) Power cables: these are indicated on the drawing as round cables with small connectors (with connectors for DCS etc at each end). How do these compare with LMTs? Round cables easier to route and would not require such large connectors at PPB1 (?) LMTs have lower mass but what is the saving? All cables would need a support structure to tie into for routing out from barrel end to PPB1 (much larger area than on current SCT). A services support structure should be included in drawings from the start. Sleeved cables could easily bash into fibre loops and cooling pipes at barrel end. 5) They are working on interlinks – agree that discontinuous interlinks are not structurally sound. Geneva did a lot of work on the current SCT interlinks – short interlinks used during integration of barrels replaced by final long interlinks. Similar concept could probably work but difficult to maintain the neat barrel end layout. Here again, we should include conceptual interlinks from the start as part of the barrel end layout. End of Stave Services: TJF