M. Modena CERN

1. “Magnets news for CLIC and ILC MDI” M. Modena CERN Acknowledgments: CERN TE-MSC CLIC Magnets Study Team: A. Aloev, E. Solodko, P. Thonet, A. Vorozhtsov 32nd MDI meeting, 13th June 2014

2. Outline: • Status for: • CLIC QD0 • CLIC SD0 • ILC QD0 • QD0 for ATF • Octupoles for ATF • Alexander Aloev will present details about magnetic design and field quality. • Note: I will present two papers next week at IPAC14: • - M. Modena et al.: “Status of CLIC Magnets Studies and R&D”, (TUPME007). • - M. Modena, A. Aloev, H. Garcia, L. Gatignon, R. Tomas: “Considerations for a QD0 with Hybrid Technology in ILC”, TUPME006) 2

3. CLIC QD0: • QD0 prototype built in 2011/2012 is now under test at LAPP (dynamic tests for stabilization R&D). (L. Brunettireports on this) • The an Helmholtz Coils measurement system, was finally receptioned and calibrated at CERN in March of this year. We have started measurements/check of the permanent magnet blocks (SmCo and NdFeB) in order to clarify the inconsistency appeared between measurements and simulation in the NdFeB blocks. Tests and simulation should proceed and be completed in the Summer.

4. CLIC SD0: SD0 design is still under finalization because we have some new interesting points under study: • We received offers for the key central components (PM blocks and the 4 Permendur sectors done by EDM). Magnet would be relatively expensive. • So we are re-evaluating the design (i.e. simplifying it from 12-blocks to 6-blocks (SmCo). This should also permit an easier check of the PM blocks quality. • Before to proceed further we have also to wait for confirmation on CLIC allocated budget for magnets R&D program. This confirmation should arrive for end of June.

5. CLIC SD0: • We are also considering a different solution to be implemented for the resistive coils, i.e. a super-ferric design (as explained at the next point for ILC QD0) • This will have no major impact on the design of the central components but could be positive effect on the cost of the EDM machining. • The most positive impact will be reduction of the total dimensions even if this is not too critical in CLIC 3 TeV. • Weight will be massively reduced (positive impact on stabilization). • Other information about field qualityin Alexander’s slides.

6. ILC QD0 study: Under the aegis of the Linear Collider Collaboration we are investigating an alternative design for the ILC QD0. The ILC QD0 baseline is today a super-conducting (coil dominated) magnet. ILD (top) and SID (right) MDI layouts: QD0 supporting cylinder inner diameter: 376 mm in SID and 600 mm in ILD (courtesy M.Oriunno and K. Buesser)

7. ILC QD0 study: • We have studied an adaptation to ILC parameters of CLIC QD0 design but also a “super-ferric” variant (i.e. same hybrid design but with small superconducting coils at the place of the low current density resistive coils). • Advantages in dimensions and weight are evident and one of the most interesting aspect is that the iron part is still “visible” so much more easy to be aligned and eventually stabilized.

8. ILC QD0 study: The required 5000 ampere-turns are carried by 9 turns of “F24” type Nb-Ti wire from the company Bruker with a cross-section of 1.8 mm2 and with 24 Nb-Ti filaments (5). The cryostat assembly (7) with its intermediate shield @75K (6) will be composed by two halves assembled around the coil packs composed by the 9 SC wire turns wound around the 4.5 K LHe cooling circuit pipe (5). Thermal shields and coil casings will be covered by a low emissivity surface protection (no multi-layer insulation presence). The other main components are: the core part in Permendur (1); the eight SmCo PM inserts (2); the post-collision line chamber (3); the return iron yokes (4) as in the resistive coils version. “Super-ferric” variant: This design takes advantage of the recent experience on manufacturing the Fast Cycling Magnet super-ferric prototype, where similar performances were successfully achieved for very compact cryostat dimensions. First calculations show that, with a protection resistance of 200 mΩ, in case of quench the coil temperature will remain acceptable in the range of 30 K. Alexander will provide other information about field quality and other possible sub-variants. (We would like to particularly thank V. Parma, D. Tommasiniand A. Ballarino of CERN, A. Yamamoto (KEK Tsukuba, Japan) and G. Volpini (INFN-LASA, Italy) for their contribution to the study and kind discussions).

9. Magnets for ATF at KEK: a new QD0 Nothing new on the design for a new compact QD0: I remind that: • QD0 should be tunable and provide ~12.5 T/m of gradient on a 60 mm diam. bore • Proposed design would be an evolution (ex. tunability) of a prototype developed at CERN for LINAC4. • Critical aspects like the stability vs. temperature, were also successfully assessed. Prototype built for LINAC4: Aperture: 45 mm, Gradient: 16 T/m

10. Magnets for ATF at KEK: two Octupoles The same (no news) on the octupoles design developed last year on R.Tomas proposal. Requirements: wide tunability; the best possible field quality for a 20 mm aperture; stability. We are waiting decisions… On this front the most important news is that important discussions are on-going between CERN and KEK Managements to propose and launch a mid-term collaboration in big part (but not only) focused on ATF future exploitation. We remain positive on that!