ABCDEFGHIJKLMNOPQRSTUVWXYZ
1
2
Snowmass’21 Accelerator Frontier – Magnets
3
Working group preliminary report: question, comments suggestions
4
5
Questions/Comments/SuggestionsNAMELab
6
version 1, 2022-06-15
7
 In current version detector magnets take ~ half of the paper. Obviously there are chalanges to build detector magnets but they are not on the same level comparing to the magnets for Muon and hadron-hadron Colliders. Suggestion: Simplify the part of the dector magnets, decreasing the amount of information adding references to the contributions. G.VelevFNAL
8
The last P5 produced HEPAP subpanel with recommendations concerning MDP (7-8 of them) summarized here:
https://usmdp.lbl.gov/hepap-subpanel-recommendations/.
They separately mention “major cost reductions”/ “breakthroughs in cost-performance”, “large improvement in cost-performance”, “cost-effective accelerator magnets using HTS”, “decrease the touch labor and increase the overall reliability”, “low cost manufacturing techniques” (so 5 out of 8 mention those). The four MDP goals, following P5/HEPAP, target “minimizing … operating margin and … training”, “LTS/HTS magnet for fields beyond 16 T”, “substantial performance improvements and magnet cost reduction”, “increase performance and reduce the cost of accelerator magnets”. The current Snowmass summary document roughly covers US accelerator magnet projects/program descriptions in ~ 1.6 pages (p), non-US programs/projects ~ 3.1 p, status and plans for pp collider magnets ~2.6 p, muon collider magnets ~ 2.7 p, ee collider magnets ~ 1.7 p, detector magnets ~ 6.4 p; conductor R&D (including cable) ~6 p, magnet R&D (design/approaches) ~5.7 p, “Diagnostics and testing techniques, technology, advanced modeling” R&D ~ 0.8 p, test infrastructure – 0.1 p, detector magnet R&D ~ 2.1 p. The document mentions (beyond quoting) “training” two times, “reliability” or “uniformity” – two times (in the context), does not mention/discuss “performance limits” (beyond quoting), improving performance is marginally marked except for REBCO; it does talk about “cost” a lot although concrete paths to fundamentally resolve the cost issues (magnet cost reduction) are limited (still made clear). My very rough estimate on existing performance “problem solving” content is ~ 1.2 p/30 p ~ 4%. The way I read the document, it suggests whatever “magnet problems” we may have they are engineering problems to be mostly resolved by (magnet) engineering solutions. Very little is said otherwise. I’d choose a different balance; I think my opinion is known.
Shall we not address/reflect more directly P5/HEPAP recommendations in some way, and probably our own MDP goals in the document, kind of continuation of efforts or evolution of understanding priorities? 		S. StoynevFNAL
9
Please check and modify the duration of the programs to be the same,e.g. page 3 seems that LArp started in 2003 and AUP started in 2013. Page 5 it is 15 years long program.G.Velev FNAL
10
THe part for effort in China and Japan are too long. THey should be shorten and merged in an Asia paragraph. THe other two efforts are US and Europe. G. VelevFNAL
11
I will suggest that Muon Collider Magnets goes before FCC. There is no chance that US will build hh collider on US soil but there is a chance to build muon collider. G.VelevFNAL
12
version 2, 2022-07-18
13
1. Fermilab test facility for HFM hybrid testing (R&D) should start to work in 2-3 years, not 3-5 years.
2. 3.1 Electron Collider Magnets -> Lepton Collider Magnets and section should include muon collider. Is ILC of the picture?		G. VelevFNAL
14
A comment on conductor costs, Tab. 5.1. Nb-Ti production per year is probably close to 2000 tons (just Bruker produces more than 1000 tons/year). HEP Nb3Sn today is about 10 times the cost of MRI Nb-Ti, on a unit weight basis. The target we had set was a factor 3 reduction for HEP Nb3Sn. I was not aware that 1 ton Nb3Al is produced every year... Who uses it ? MgB2 is approximately as expensive as Nb3Sn today. REBCO is about 2...3 times more expensive than Nb3Sn on a unit length basis, 4 times Nb3Sn on a unit weight basis (for identical current carrying capacity). Bi-2212 is indeed about 10 times Nb3Sn, so about 100 times Nb-Ti.

What I miss is a statement of what should be the work for the coming (say) ten years. I think that before the conclusions it would be useful to identify what is your, and the Snowmass community view of where the priority should go.

A suggestion, as it does not appear in your report, is to add the potential impact of the magnet development on other fields of science and society		L. BotturaCERN
15
1 Summary, it is now close to 2 pages, work in progress, where we are missing the clear messages to Snowmass community. Needs to be clear what is technology ready, what needs technology development and how much time & effort is needed
2 ILC is missing, Sasha answers that we can add it.		G. VelevFNAL
16
1. The report now is more a scientific paper than a proposal. It should make clearer what is the work needed to align with the machine proposals
2. How the report turns to a proposal? Sasha answers that our goal is to provide information and not a proposal. Some clear messages on what is needed.
3. Try to sell our technology more to other fields.		L. BotturaCERN
17
1. Agree on the messages in the executive summary. How critical each technology is for each machine, muon colliders vs fcc-ppS. PrestemonLBNL
18
1. In other frontiers, more from machine perspective, items come with a list but not with priority. Ideally all community should be on-board with the vision, although it is challenging.
2. Directed vs non-directed R&D? focus on the types of magnets we are interested in. what should be taken care in the US, what is being done somewhere else?
3. GianLuca asked if there is potential conflict between MDP and LEAF.		E. BarziFNAL
19
1. Axion magnets, how do we put then in? some magnet might be like muon colliders, some close to detectors
2. Velev points out that at FNAL there is a group working on it. They are not small magnets, there are few, it is important to get clear requirements. If there is enough founding some of them are feasible with current technology some of them require developments. Lindley will send something with the clear requirements.		L. WinslowMIT
20
1. Performance is not part of the executive summary. Do we need to address a problem of performance that needs to be adressed? Suggested text: "The accelerator magnet community recognizes persistent magnet performance issues often obstructing designs/technologies to reach their full potential. Some of those are conductor-specific but others are less so and can be tracked long back in time. While work to address difficult points is ever on-going, resolving them may require new or more focused research approaches going deeper into phenomenon investigation in ways not fully explored in past."
S. StoynevFNAL
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100