Muon Collider Ring Magnet Progress

1. Muon Collider Ring Magnet Progress Alexander Zlobin Technical Division Fermilab

2. MC Ring Magnet Parameters Muon Collider Ring Magnet Progress

3. MC IR Magnet Parameters MAP Proposal: • “Work on collider lattices must go hand-in-hand with the magnet, superconducting rf, and detector studies”. • “The proper design of this ring is a prerequisite for the success of the whole project”. Muon Collider Ring Magnet Progress

4. Magnet Design Study Issues • Superconductor choice to provide the required Gnom (Bnom) in MC Ring magnets (Q and D) with the required apertures • Magnet operation temperature and margins • Field quality • Lorentz forces and stress management • Magnet radiation heat load, lifetime, protection • Coil cooling and heat removal • Magnet quench protection (magnet inductances and stored energy) • etc. Muon Collider Ring Magnet Progress

5. From P. Lee Superconductor Choice • Baseline conductor – Nb3Sn • Best combination of properties (Jc, Tc, Bc2, stress sensitivity) • Commercially available strands in long length • Good progress in Nb3Sn accelerator magnet technologies Muon Collider Ring Magnet Progress

6. Large-aperture IR Quadrupoles • Practical 2-layer designs, Bnom~11-12 T, Bmax~13-14 T • Operation margin ~10% @ 4.5K (~20% @ 1.9K) • Operation at 4.5K more preferable • 10% is OK for Nb3Sn magnets based on LARP studies • Good field quality aperture (<1 unit) ~2/3 coil ID • Quench protection looks OK (short magnets) • Max stress in Q2, Q3 >150 MPa => Nb3Sn conductor degradation (OK based on recent LARP results) • Nb3Sn IR quads with aperture 90-120 mm are modeled by LARP Muon Collider Ring Magnet Progress

7. 8T IR Dipole • Traditional 2-layer design • Bmax(4.5/1.9 K) ~12.5/13.5 T • Margin ~55% @4.5K (~70% @1.9K) • Good field quality inside R<55 mm • Coil shielding in the midplane • shorter magnet, inner absorber, low-Z material in coil midplane, • Open midplane • New design concept • Bmax(4.5/1.9 K)~9/10 T • Margin ~10% @4.5K (~20%@1.9K) • Field quality is limited • Large stored energy => factor of 5-8 larger than in present LHC IRQ • Design studies: margin, field quality, stress management, quench protection. • Modeling: can we make such magnets!? Muon Collider Ring Magnet Progress

8. First Radiation Studies • Radiation studies have been started (V. Alexakhin, N. Mokhov) • 3 designs with masks: Standard optics, 5-sigma internal absorbers, shifted Q • Muons and Neutrons, Gamma and Electrons • Power distribution, heat load, radiation dose, etc. • Preliminary results are quite encouraging • Issues: • high heat load in masks, • sagitta in 6m long dipole • Study will continue Muon Collider Ring Magnet Progress

9. 10T Ring Dipole • High heat deposition (0.5-1kW/m) in magnet midplane => large power consumption => open midplane magnet design • Coil design options: shell-type vs. block-type • Coil support => mechanical stricture • Coil cooling => indirect cooling scheme is needed Aperture – 60mm Bop~10T with ~10% margin at 4.5K. Midplane gap: ~10 mm • New challenging design => model magnet R&D. • FNAL plans (HFM program): • FY10 : coil, structure, tooling design and procurement • Practice coil, inner coil fabrication and test • FY11: outer coil fabrication, 1st model test • FY11-13: design and performance optimization Muon Collider Ring Magnet Progress

10. Conclusions • The level of efforts on MC ring and IR studies (including magnets) has been significantly increased • Collaboration of accelerator, magnet and detector groups has been established • Significant progress has been made in 2009: MC lattice and IR optics, magnets, radiation studies, dynamic aperture… The work will continue. • Present MC Ring magnet parameters are at the limits of Nb3Sn technology • To achieve these parameters magnet design studies and experimental R&D program are needed • Large aperture quadrupole - input from LARP • Collider and IR Dipoles – to be demonstrated! Muon Collider Ring Magnet Progress