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ArcHalfCellMock-up Meeting #6

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Federico Carra (CERN)
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Notes of Meeting Arc Half Cell Mockup #6

28th April 2023

List of people attending the meeting: 

F. Carra (chairman), J. Bauche, L. Baudin, A. Bertarelli, J. Coupard, H. Mainaud Durand, C. J. Eriksson, F. Valchkova-Georgieva, R. Kersevan A. Piccini, T. Raubenheimer, R. Rinaldesi, S. Rorison, C. Tetrault, M. Timmins.

Slides of the presentations are available in the Indico page related to the meeting (https://indico.cern.ch/event/1278881/).

Agenda:

  1. Introduction of the project phase 2 (T. Raubenheimer)
  2. Mock-up meetings: Practical aspects and next steps (F. Carra)
  3. Midterm review report (L. Baudin)
  4. Magnet installation sequence (J. Bauche)
  5. Cost estimation magnet’s support (M. Timmins)

F. Carra opened the meeting informing that Phase 1 of the FCC-ee Arc Half-Cell Mock-up project, which consisted of studying a basic model of the Arc Half-Cell, was completed at the end of last year. In Q1 2023, the team wrote a thorough documentation of it (see also section 2 of these minutes). Phase 2 will now begin and will focus on the mock-up study. Moreover, this workpackage is continuing the coordination of the activities related to the arc (section 1 of these minutes).

 

1) Introduction of the project phase 2

T. Raubenheimer gave an introduction of the project phase 2. The phase 2 will continue to examine the integration of the different elements of the arc. During this phase, list of main opened points to be addressed must be identified. For instance, the following questions should be answered: What are the outstanding interfaces? What are the engineering studies that need to be done before building the mock-up? What is the optimal elevation of the beam line? The alignment strategies should be clarified. Several safety aspects such as how to cross from the corridor to the other side of the beam line should be taken into account.

The phase 2 should include the detailed engineering of the components of systems installed in the arcs.

F. Carra observed that the arc cell mock-up project then will continue to be a platform for the discussions between the stakeholders included in the design and installation of systems in the FCC arcs. This is an evolution of what initially discussed one year ago, where the Phase 2 was supposed to focus on the mock-up construction only.

F. Carra asked if the cost estimation should be also provided. T. Raubenheimer answered that, indeed, cost estimation is part of the mandate of this working group.  

T. Raubenheimer also added that, with respect to the initial mandate discussed one year ago, we can consider of slightly shifting the construction phase of the mock-up and consolidate more the arc configuration. The aim is now to start building the mock-up by the end of 2025.

F. Carra mentioned that it would be interesting to anticipate the fabrication or prototyping some elements of the mock-up in 2024, by manufacturing key elements such as the jacks and the girder. Prototyping of the key components would help the cost estimation. M. Timmins added that these elements weigh heavily on the FCC Arc Cell’s cost (see section 5 of these minutes). A detailed design and engineering of these jacks would allow cost optimisation.

A document (or short presentation) will be prepared by T. Raubenheimer and uploaded on the indico to summarise the mandate, timeline and deliverables expected for the Phase 2 of the mock-up project (action Tor).

 

2) Mock-up meetings: Practical aspects and next steps

F. Carra presented slides related to practical aspects and next steps of the mock-up meetings. The Indico page for the Phase 2 can be found on the following link: Phase 2: Mock-up detailed design (from January 2023) · Indico (cern.ch). A. Piccini will replace L. Baudin  as scientific secretary of the project. For the meetings, it is proposed to keep the same slot as Phase 1: Tuesday 3PM, alternating with Accelerators Pillar meetings. Once per month, there will be a report to the Accelerator Pillar meeting. A. Piccini will send the current member list to the e-group (fcc-ee-arc-cell-mockup-project): please let us know if anyone should be added/removed from it. The list of the senior advisors will also be reviewed (action Audrey).

F. Carra explained that meetings dedicated to specific topics will also be organised. For instance, colleagues from Beam Instrumentation will be contacted, to discuss the integration of BPM in the SSS. This is also an action assigned to the Arc Half-Cell project, coming from a past Technology R&D meeting, chaired by R. Losito. T. Raubenheimer emphasized that the alignment of the sextupoles with respect to the quadrupoles of each girder is a major topic which should help to define what is the ultimate quality of BBA that can be obtained. T. Raubenheimer reminded that a Tuning workshop will be organised on the 28th of June.

F. Carra described the documentation prepared for phase 1 (see slide 4). A. Piccini will upload on the indico page of the mock-up projects the documents produced during the Phase 1: Phase 1 report, IPAC 23 article, ICFA Newsletter (action Audrey).

Finally, F. Carra outlined 2023 key dates and asked for details of the dates of the Mid Term review. T. Raubenheimer confirmed that the mid-term review will take place around the 16-18 October 2023. There will be one review for the cost and one technical.

F. Carra asked T. Raubenheimer if a calendar of upcoming events could be maintained and communicated to all the members of the projects. T. Raubenheimer  answered that such calendar is available on TWiki but it is not always up to date.

 

3) Midterm review report

L. Baudin presented the outlines of the midterm review report, explaining that there are many cross-references to considered. She gave some of the parameters that have been considered and asked if they need to be updated and if, for example, the horizontal configuration (booster vs. collider) should always be presented?  

J. Bauche indicated the importance of keeping both diameter options for vacuum chambers (60 and 70 mm). He will be presenting both options at the FCC week.

J. Coupard pointed out that Integration team has been asked to present the vertical configuration as the chosen one, but also the horizontal should be recalled, as it is that of the CDR, and to explain which choice had been made and why. The evolutions from the CDR should be presented. T. Raubenheimer agreed that the parameters and how they were chosen should be highlighted. It is possible to make changes even after the FCC week until somewhere in September. 

T. Raubenheimer precised that outline breakdown structure of the report should have been ready, and first drafts should have been provided by the end of April . The current breakdown structure is available on the TWiki. The final document should be ready by the end of September.

L. Baudin and F. Carra will complete a first draft of the paragraph 5.3 on the FCC-ee Half Arc Cell mock-up project by week 18. The study about the optimal vertical coordinate of the booster beam line (request from management is if it can be lowered) will be ready on time for the review this autumn (action Lucie and Fede).

4) Magnet installation sequence

J. Bauche explained that he wants to take the opportunity of this half-arc cell meeting where main stakeholders of the magnets installation in the arcs are present to show his initiative and ask feedbacks on the magnet installation sequence. He presented an excel file in which he described the magnet installation sequences: in the tunnel, for dipole assembly and for SSS assembly. He presented this document as a draft that needs to be completed and refined. He asked the different groups involved (Survey, Electric Powering, Vacuum, Infrastructure, Transport etc.) in this installation to contribute to filling in this file. 

H. Mainaud Durand pointed out that some steps needed to be added:
About the installation in the tunnel, the first task is to install and measure a geodetic network. A step “control of the supports” should be added in the table (task 1.5). H. Mainaud Durand also reminded that smoothing of all the elements should be performed after the electrical and vacuum connections.

About the girder assembly and the SSS pre-alignement, H. Mainaud Durand explained that it would be interesting to use what was done for the PACMAN project to automate the installation of the magnets on the girders: assembly, fiducialisation and calibration. In her point of view, the shimming of 3000 girders is not realistic without a finally automated procedure.

F. Carra asked if it is possible to read something about PACMAN studies. H. Mainaud Durand replied that a lot of documentation is available after the extensive work of 10 PhD students. She proposed to give a short overview on what have been done for PACMAN project (action Audrey to add it to the list of topics for next meetings and discussed best slot with Helene). 

J. Coupard observed that the installation of components in the tunnel is part of the mandate of the Technical Infrastructure group, and she commented that this exercise should be done under the TI umbrella. F. Carra agreed that we should coordinate with the TI, to avoid duplication of activities. R. Rinaldesi reminded that the transport and installation of the components is in the scope of a collaboration with the colleagues of the Fraunhofer institute IML. In this sense, the document just drafted by J. Bauche, with some finetuning, can already be useful to the Fraunhofer colleague. 

J. Bauche and R. Rinaldesi encouraged all the stakeholders involved in the magnet installation sequence to provide rough estimation of each of the task listed in the table presented by J. Bauche. The table will then be shared with the TI team, to be included in the wider study ongoing.

 

5) Cost estimation magnet’s support

M. Timmins has been contacted by A. Unnervik  in order to provide a cost estimate for the FCC-ee magnet supporting system. M. Timmins set the estimate for arc region; for interaction regions the estimate will be provide by the MDI working group, as the Half Arc Cell mock-up project is not involved in the design of MDI magnet supporting systems. J. Bauche commented that magnets were omitted by the coordinators of the costing exercise. This mistake has been corrected. F. Carra asked about the pre-injectors supports, and T. Raubenheimer replied that this will be under the responsibility of the Injector working group.

M. Timmins presented an excel file in which he described the cost estimation of an FCC Arc Cell. He asked for feedbacks during the meeting as he was requested to send a first table by the end of that day.

M. Timmins concluded that components used in large quantities, such as jacks, had a significant impact on the final cost. It has been pointed out that the cost of the HL-LHC jacks (6k) is probably overestimated as it is the cost of about twenty prototypes and produced in large series this cost should decrease (idem for UAP tables). As the costs of the elements are explained and detailed, for the final calculation a scaling can be made on the costs of prototypes.

H. Mainaud Durand commented that such cost estimate (comparison between HL and PSI jacks or UAP ) should not trigger design decisions, especially because if the cost of one item is based on prototype cost. The alignment strategy should first be defined, then the engineering and cost optimisation will be performed on supporting elements which fulfil the needs of the alignment strategy.

T. Raubenheimer asked for each item if the cost has been estimated based on prototype or series cost. This information can be added in a column of the excel file. H. Mainaud Durand commented that abaqus were used in the cost estimate of CLIC to extrapolate cost for large series. F. Carra commented that A. Unnervik could provide guidelines. 

T. Raubenheimer precised that the cost is corresponding to the Higgs and TTbar phases (for TTbar phase only the RF are different wrt. Higgs Phase).

M. Timmins remarked that building the mock-up would be the opportunity to better optimise and estimate the manpower cost for pre-alignment of collider and booster components.

 

 

Actions follow up

  1. T. Raubenheimer will provide a written document to summarise the mandate, timeline and deliverables expected for the Phase 2 of the mock-up project.
  2. A. Piccini will send the current member list to the e-group: please let us know if anyone should be added/removed from it.
  3. A. Piccini will upload on the indico page of the mock-up projects the documents produced during the Phase 1 : Phase 1 report, IPAC 23 article, ICFA Newsletter. Done, deliverables are reachable at https://indico.cern.ch/event/1283361/
  4. L. Baudin and F. Carra will complete a first draft of the paragraph 5.3 on the FCC-ee Half Arc Cell mock-up project by week 18.
  5. H. Mainaud Durand will give a short presentation on what have been done for PACMAN project.
  6. L. Baudin, F. Carra and A. Piccini will send the next meeting invitation.
  7. F. Carra and A. Piccini take part to the Tuning workshop on 28th of June
  8. L. Baudin, F. Carra and A. Piccini will contact people in charge of arc components installation in TI working Group (Sarah Fleury) to coordinate the efforts in defining the installation sequence.
  9. L. Baudin, F. Carra and A. Piccini will contact colleagues from Beam Instrumentation (M. Wendt) for a thematic meeting about BPM integration. Done, meeting planed on 4th of May
  10.  All stakeholders involved in the magnet installation sequence should provide rough estimation of each of the task listed in the table presented by J. Bauche.
  11.  M. Timmins will contact A. Unnervik to clarify cost scaling methods to apply for large series. Done, meeting planed on 4th of May

 

Minutes written by: Audrey Piccini and Lucie Baudin.

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