IR Magnets for Muon Collider Alexander Zlobin and Vadim Kashikhin Muon Collider Physics Workshop, Fermilab November 12, 2009

2 WG3 - Machine-Detector Interface 11/12/09IR Magnets for Muon Collider Outlines MC IR optics and nominal magnet parameters Magnet margins and target parameters Magnet design concepts, parameters and issues –IR quadrupoles –IR dipoles Summary and next steps

3 WG3 - Machine-Detector Interface 11/12/09IR Magnets for Muon Collider MC IR Design (Eliana/Yuri) corrector s sextupole s bends Dx (m) quads  y  x Chrom. Correction Block RF multipoles for higher order chrom. correction Magnets: Large-aperture high-gradient quadrupoles Large-aperture dipoles Strong sextupoles Multipole correctors

4 WG3 - Machine-Detector Interface 11/12/09IR Magnets for Muon Collider Final Focus Nominal parameters: IR quad length < 2m (split in parts if necessary!) – no shielding from inside full aperture D = 10sigma_max + 2cm Margins and target design parameters: Coil aperture ID=D + 10mm (3mm beam pipe + 2mm He channel) Operation margin Bmax/Bnom 20%

5 WG3 - Machine-Detector Interface 11/12/09IR Magnets for Muon Collider Design Study Questions Can we provide the required Gnom (Bnom) in MC IR magnets (Q and D) with the required aperture using Nb3Sn conductor? What are magnet operation temperature and margins? What is good field quality aperture? Are Lorentz forces and stresses in the coil acceptable? What are magnet inductances and stored energy?

6 WG3 - Machine-Detector Interface 11/12/09IR Magnets for Muon Collider IR Quadrupoles

7 WG3 - Machine-Detector Interface 11/12/09IR Magnets for Muon Collider Gmax/Bmax vs. Coil ID and T

8 WG3 - Machine-Detector Interface 11/12/09IR Magnets for Muon Collider IR Quadrupole Issues Bmax(1.9K/4.5 K)~15T/13 T –LARP TQ best results ~12T/13 T at 4.5K/1.9K Bnom~11-12 T Operation margins 1.9K and only 4.5 K –Operation at 4.5K more preferable –Usually 20% for IRQ but 10% maybe OK for Nb3Sn magnets 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 –use Nb3Al –stress management Open questions: Is margin sufficient? Do we need internal absorbers (larger aperture)? Can the IRQ maximum/nominal gradient be increased?

9 WG3 - Machine-Detector Interface 11/12/09IR Magnets for Muon Collider IR Dipole

10 WG3 - Machine-Detector Interface 11/12/09IR Magnets for Muon Collider Dipole Issues Traditional 2-layer design –Bmax(1.9K/4.5 K)~13.5T/12.5 T –Operation margins 1.9K and 4.5 K –Good field quality inside R<55 mm –Coil shielding in midplane  use low-Z material in midplane  Split magnet and insert absorber Open midplane –New complicate design –Bmax(1.9K/4.5 K)~10T/9 T –Operation margins 1.9K and 4.5 K –Poor field quality Large stored energy => factor of 5-8 larger than in present LHC IRQ Coil stress management needs more studies Questions: margin, design, field quality, quench protection,… Can we make such complicate magnets!?

11 WG3 - Machine-Detector Interface 11/12/09IR Magnets for Muon Collider Conclusions Present MC IR optics pushes the magnet parameters to the limits of Nb3Sn technology To achieve these parameters magnet design studies and experimental R&D program are needed –Large aperture quadrupole - demonstration –Dipole - demonstration –Correctors - concept Radiation studies and magnet shielding are critical to optimize magnet operation margin and lifetime MC IR optics need further optimization taking into account the constraints from magnet designs