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v3.3.5-pre
Discussion about recent findings identified during the TDIS P2 in-tunnel alignment and also while assembling the TDIS P8 on surface.
Meeting via Zoom:
https://cern.zoom.us/j/6533491608?pwd=aGx6dStSYmY4dnVzV1AvZlU5RE9rdz09
A discussion took place on the recent alignment issues related to TDIS P2 (already installed in the LHC) and TDIS P8 (being finalized in 927). Below is the outcome of the meeting along with next actions:
- After few iterations, it turns out that the alignment issue identified at TDIS P2 might simply result from a misunderstanding about how to place the device wrt a given reference. In this case the TDIS axis was being positioned parallel to the injected beam (B1 beam) while there must actually exist a 0.094deg-angle between both elements. Such hypothesis shall be confirmed if possible by Wednesday 02/09 by the survey team in order to unblock TDIS P8 assembly flow (currently stopped before continuing with the on-surface alignment). SMM-ASG will also investigate whether the jacks are properly installed, both in P2 and P8 and provide a statement by Wednesday.
- STI-TCD will then inform the relevant teams (vacuum, electronics, transport, coordination etc.) what are the next steps on TDIS P2
- SMM-ASG to provide a planning before Friday morning covering next alignment activities for TDIS P8 and liaise with coordination.
- STI-TCD to provide a TDIS P8 installation planning to the coordination team by Friday (04/09)
- STI-TCD to set a biweekly meeting with SMM-ASG for the next two months to follow up on the alignment work to be conducted on the TDIS units over the upcoming months
- SMM-ASG and STI-TCD to agree asap on the content of alignment reports
- SMM-ASG to draft a TDIS alignment procedure assisted by STI-TCD (due date to be defined, but not before October)
- Correction on slide #8: the deviation is actually 2 cm (instead of 0.2mm), which is due to a combination of the tunnel slope effect, irregularities of the vault and the rails fixation points tracing mix-up (data corresponding to the average beam axis was assumed to be referenced to circulating beam axis)
- The last subject, brought up by Jean-Frederic after the meeting, is the orientation of the TDIS P2 downstream QRL-side jack. In the drawings it is rotated by 180 deg with respect to the position requested by SMM-ASG and so is it at the TDIS P2 slot. The issue is that an existing opening on one side of the jack intended to fit in there the vertical adjustment hydraulic pump is currently facing the QRL side so the accessibility is poor. The assembly drawings LHCTDIS_0001 and LHCTDIS_0236 shall therefore be corrected and the issue fixed at the P8 location (at P2 SMM-ASG can accept to cope with this minor non-conformity in order to avoid a new handling of the device). This information will be added to the alignment open NCR (EDMS 2407349)