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ArcHalfCellMock-up Meeting #11
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ArcHalfCellMock-up Meeting
Notes of Meeting Arc Half Cell Mock-up #11
13th March 2024
List of people attending the meeting:
F. Carra (chairman), J. Bossy, B. Dalena, C. J. Eriksson, H. Gamper, M. Guinchard, K. Hanke, E. R. Howling, P. Lersnimitthum, K. Oide, A. Piccini, S. Rorison, M. K. Rouchouse, G. Roy, C. Tetrault, M. Timmins, F. Valchkova-Georgieva, L. Von Freeden.
Slides of the presentations are available in the Indico page related to the meeting (ArcHalfCellMock-up Meeting #11 (13 mars 2024) · Indico (cern.ch)).
Agenda:
1) General information on the Mock-up project (F. Carra)
2) Introduction to the new “Accelerator technical design pillar” (J-P. Burnet)
3) Arc Half Cell Mock-up updates (F. Carra)
4) Arc Half Cell SSS Demonstrator design (M. Timmins)
1)
F. Carra introduced the meeting explaining the aim of this meeting is to summarise the ongoing activities in the FCC-ee AHCM project. Then, he added that for the next meeting we will try to do a hybrid one.
2)
J.-P. Burnet did not connect to the meeting, so F. Carra suggested checking with him whether he can upload these slides and/or present them at the next meeting (action Audrey). Goal of his presentation is to introduce the new structure of the Accelerator Technical Design Pillar.
3)
F. Carra presented the status of the AHCM project.
It is important to note that given the request to speed up project deliverables, the schedule has been revised from that agreed with T. Raubenheimer at the launch of phase 2. Normally, production of the 1:1 scale mock-up was due to start at the beginning of 2025 targeting installation by the end of 2025, whereas now the target for the installation is Q1 2025. The version installed in early 2025 will be mostly a non-functional, visual one., but the mock-up is a structure that is supposed to continue to evolve in the following years.
Two key actions are underway:
1. Building an Arc Half Cell SSS Demonstrator: this demonstrator will be functional, 2.5m long, with existing hardware or coming from collaborations. The aim will be to understand the impact in terms of stability. To understand the budget of the different components in term of stability, to benchmark the simulations currently ongoing, to have a critical view of the specifications given: are they too tight?
2. Building the 1:1 scale Mock-up: initially this mock-up will be non-functional with 1:1 scale and a length > 15m (will depend on the space available).
Regarding the 1:1 scale mock-up F. Carra ask what people think about the cross section presented in the slide. B. Dalena confirmed that the baseline distance between collider and booster is 160mm (booster towards the centre). Of course, this distance will surely evolve as it depends on the offset at the interaction points and the injection.
F. Valchkova-Georgieva added that she had shared the latest version of the cross section at the Technical Infrastructure meeting 13/03/2024 (Technical Infrastructures coordination meeting #59 (13 mars 2024) · Indico (cern.ch)). In this version, the distance between machines on the horizontal plane is indeed 160 mm.
M. Timmins suggested freezing this version for the mock-up and having it formally validated with a drawing code. G. Roy added that the longitudinal view should also be considered in the validation process. F. Carra asked F. Valchkova-Georgieva if it was possible to update the CATIA model and shift the SSS collider in relation to the SSS booster. G. Roy confirmed that the aim will be to maintain the shift between the two SSSs across the whole length of the ring.
F. Carra took the opportunity to ask whether the HFD booster lattice presented at the booster day (FCC-ee Arc Cell Integration_FV.pdf (cern.ch)), with much larger magnets, was still just an option, which B. Dalena confirmed: the baseline is still the FoDo lattice. L. Von Freeden added that even if the lattice is not modified, the magnets will probably be larger than expected. the aperture is now fixed at 65mm in diameter. In addition, a fellow has been actively working on the design of the dipole booster and, as the busbar has been removed from the centre of the magnet, its cross-section will be larger. He concluded by saying that a new dipole design would be available in 1 or 2 weeks. Hence, F. Carra proposed to F. Valchkova-Georgieva to wait a few weeks before sending the 3D model to M. K. Rouchouse, and to organise a kick-off meeting for the 1:1 mock-up to agree on the design to follow (action Audrey). The structure of the team involved in this 1:1 mock-up is presented in the slides.
4)
M. Timmins presented the Arc Half Cell SSS Demonstrator design.
M. Timmins recalled that the construction of this demonstrator is part of the experimental campaign presented last year, i.e. to characterise the different systems of the SSS collider in terms of stability to understand the budget of the different components in term of stability, to benchmark the simulations currently ongoing and to have a critical view of the specifications given.
It is important to note that this demonstrator is mainly composed of elements already existing at CERN (quadrupole prototype, jacks…). At least two girders will be tested, including one from the collaboration with PAEC, which will also be used to test the feasibility of a 0.15mm flatness.
Another key point is to note that this demonstrator has a stiff design on purpose, we want to see what performances in term of stability can be achieved under optimum conditions.
Regarding the schedule slide, F. Carra mentioned that the step ‘Select most promising solution to build full scale mock-up’ will be split into two different steps: from non-functionable to functionable, it will avoid slowing down the fabrication of the 1:1 scale mock-up.
G. Roy pointed out that geodesy also needs to be involved, for example a structure on 4 jacks can be challenging for them. M. Timmins replied that the team is fully aware of this, in fact, it is a very well-used installation at PSI.
Finally, F. Carra asked L. Von Freeden and C. J. Eriksson if other prototype magnets were expected, since they could be integrated into the mock-up. L. Von Freeden indicated that they planned to build a short dipole protype by the end of the year. The main role of this prototype will be to test its magnetic behaviour.
Actions follow up
1) A. Piccini will contact J.-P. Burnet. (Done)
2) A. Piccini will organise a kick-off meeting for the 1:1 mock-up. (Done 21/03)
3) F. Carra will give a presentation for the ACE seminar (22.03.2024) as well as at the Space Manager Forum to ask for the mock-up space (19.03.2024).
Minutes written by: Audrey Piccini
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