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LS3 IVO meeting
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Europe/Zurich
30/2-005 (CERN)
LS3 planning
General status
The SPS magnet exchange campaign that had previously been planned for October has moved to February. Three separate campaigns during February-August period.
Vacuum consolidation in TI2 was also discussed. For TI2/TI8, vacuum work mainly requires an intervention at the beginning to open/disconnect and another intervention later. This gives some flexibility in accommodating changes to the global schedule.
TDC2 disconnection work is planned early in January. The SPS magnet campaign may have to move in case of issues. This was not considered critical because there is approximately four weeks before the February magnet campaign and the amount of work is small
BST has shifted substantially and is not expected to be ready before the end of the year, with only one half-cell targeted before Christmas. BST schedule does not change the venting and opening strategy. Other activities require the same openings, so the present opening sequence will be maintained. The main potential effect concerns when systems can subsequently be closed.
Local leak detection of the QXL is expected in 2028. The team has been asked to take responsibility, but this was not yet official and needs first to be discussed with Paolo. Resources are expected to accompany the activity. Guillermo will follow the activity. The main concern is tooling readiness, as clamshells need to be designed, produced and tested in advance. The tooling could be prepared internally or with MME support, but clear responsibility is needed to ensure everything is ready before the intervention.
The global leak detections are completed at LHC IV. However, detailed envelope work is at different stages depending on the sector: some ARC areas are finished while QRL work is still starting or incomplete. Status => https://cernbox.cern.ch/files/spaces/eos/project/v/vsc-ls3-iv/CERN/Leak%20test/LS3_leak%20status.xlsx
Before Christmas, SPS work is primarily focused on RGA measurements and leak detection on the cavities in BA3. A bake-out of vacuum sector 635 after replacement of the septum planned after Christmas will be likely postponed/cancelled.
Ion-pump consolidation activities are starting at BA1, including work in the switchyard and subsequently in the Booster.
BSW / large-flange tooling
Specific tooling is required for the BSW intervention to support the large flange and bellows assembly. The flange is heavy enough that it must not remain hanging from the bellows when the assembly is transported or removed.
The tool connects the flange assembly to the mechanical support to make the system rigid. It was initially developed around LS2 and has subsequently been modified/improved.
Paul knows the tooling and has installed it several times. Some fine adjustment may still be required, and it therefore needs to be prepared a few days before the intervention.
Action: Check with Paul that the complete tooling is available and ready before the intervention.
PSB quad replacement
Four quadrupoles were identified as leaking after helium testing of the cooling circuits. Particular attention is required for chamber 11, which has a specific offset configuration and a shorter bellows.
AD/ELENA
Acceptance testing of a SEM grids is under way in the laboratory.
Quadrupole removals in the AD area were expected to start next week. Quads 27, 28 and 29 will be removed.
LEIR magnet intervention
The magnet DHV42 had been removed and the machine repumped immediately afterward. Both sides reached pressures around the 1e-8 mbar range. The chamber is being prepared in the workshop (cut and weld). The preference is to carry out the bake-out as early as possible, provided the system is ready, resources are available and the relevant stakeholders agree.
Action: Check with the relevant coordination/stakeholders and proceed with an early bake-out if there is no blocking issue.
FSU planning
Over the next weeks, the main FSU activity is ion-pump consolidation. The FSU personnel have CERN accounts and can be given access to the necessary internal resources. A computer/laptop would be useful for activities such as updating tables, signing off consolidation work and completing Excel-based follow-up in the laboratory or office.
Action: Check the laptop/computer arrangement and provide an appropriate machine if required.
Chamber production and workshop follow-up TT2
For the TT2 BHZ magnets jobs BHZ magnets: BHZ117: completed and BHZ147: ongoing. Xavier will check the status and report next meeting
FTN chamber jobs were stated to have been launched, including the dipole chambers.
Action Xavier: Check the corresponding job numbers and enter them in the follow-up file.
BTY status is to review
Action: Check with Nicola and workshop that the latest correct drawings are being used, particularly before welding the supports.
MBSA prototype
Leak-detection tooling SPS MBSA magnet existing leak-detection tooling has an internal gap for a seal. 7 mm Viton cord of the required diameter had been identified as an alternative. For joining it will be done as in LHC gluing two extremities. 90° cut superglue to glue both extremities, ideally with a tool to align them properly and then polish to obtain a smooth surface. Guillermo has done this previously and should be consulted.
Large SPS collar
SPS large collar had not yet been delivered, although two prototypes were available. Production had already been released to the company. The delay is not currently blocking leak detection, because approximately three or four existing collars were reported to be available in stock. The new collars should nevertheless be tested when available to verify that they work correctly. Potentially reusable clamps/tooling from older equipment in long-term storage were also discussed.
Laboratory activities
The D-box assembly for PUMA testing is under way.
The new VAT gas-injection valve had arrived. Equivalent to the older Pfeiffer EVR116, operated at 24 V with a 0–10 V control signal. It will be tested in the laboratory.
Septum 16 spare: There is concern that the Septum 16 spare magnet may not be operational. If it cannot be made to work, one of the older magnets may need to be installed instead.
SPS cavity leak investigation
Cavity #5 has a leak since installation in the SPS/BA3 area. The leak had previously been approximately localised but not precisely identified. The recent intervention successfully reproduced and further localised it. RGA measurements are also being carried out on each cavity to establish reference spectra. Leak localisation The suspected leak was associated with the flange/joint region. Applying temporary sealing material to the suspected area produced an immediate pressure improvement, strongly indicating that the leak in that region dominated the vacuum behaviour.
The discussion reports pressure going from around 1e-6 to around 1e−8 after the repair.
Leak detection continues and an additional leak on cavity 6 was found at the level of the seal of the drift tube. Varnish had already been sprayed and the area will be retested.
A historical technique was discussed in which varnish was diluted with approximately 50% acetone to make it sufficiently fluid to inject into narrow gaps.
Septa ion-pump consolidation
There are 25 pumping modules, with two ion pumps per module. The pumps are approaching end of life and some are starting to fail. The existing pumps are several decades old. Replacement pumps from Agilent do not fit directly within the available envelope, so modified pumps are being procured.
The replacement pump is slightly shorter. An intermediate plate has been designed so that the existing base arrangement can largely be reused.
Two modified pumps are expected in January. Once the pumps and intermediate plates are available, the intention is to assemble and test a prototype. Once the prototype has been validated, the proposal is to produce a limited number of units progressively rather than replace everything immediately. 11 spares that could effectively be rebuilt/prepared in the laboratory. Exchange of modules could then be coordinated with ABT when maintenance is performed on the corresponding septa.
The existing chambers/module hardware will generally be reused, with the principal intervention being replacement of the ion pumps.
SPS truck
Jarmo and Anthony have reported a problem with the SPS truck at the end of the meeting. Initially it was described as a failed gearbox.
Action: Have the truck inspected/diagnosed by the garage.
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