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Status Update on Muon Collider Ring Design: Progress and Challenges (2011)

This document presents the current status of the Muon Collider ring design, focusing on the 1.5 TeV center-of-mass (c.o.m) baseline design and outlining a comprehensive task list. Highlights include recent progress in the areas of IR dipole multipole errors and fringe fields of IR quads, as well as collimation schemes and plans for a 3 TeV c.o.m lattice. The insights provided stem from discussions held during the Muon Accelerator Program (MAP) meeting at Jefferson Lab in early 2011. Detailed results on collimator design and fields in quads, as well as future requirements and simulations, are also included.

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Status Update on Muon Collider Ring Design: Progress and Challenges (2011)

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  1. Status of the Muon Collider Ring Design Y. Alexahin (Fermilab APC) • Baseline design (1.5TeV c.o.m.) • Task list • Recent progress - effect of IR dipole multipole errors (A.Netepenko) - fringe field of IR quads (V.Kapin) - collimation scheme - 3TeV c.o.m Lattice (Eliana) • Plans Muon Accelerator Program Winter Meeting, Jefferson Lab, 02/28-03/04/2011

  2. 2 1.5 TeV c.o.m. MC IR Layout y x Dx Rendition by A. Netepenko MC Design Status- Y. Alexahin MAP meeting 03/02/2011

  3. 3 Coil aperture mm 160 Gap mm 55 Nominal field T 8 Nominal current kA 17.85 Quench field @ 4.5 K T 9.82 Rref=40mm b1=10000 b3=-5.875 b5=-18.320 b7=-17.105 IR Dipole IR dipole coil cross-section and good field region Calculated multipole components MC Design Status- Y. Alexahin MAP meeting 03/02/2011

  4. 4 Task List - I • Lattice Design • fringe field & systematic multipole correction • *-tuning sections • collimation scheme • closed orbit & optics correction scheme • injection & abort • monochromatization scheme (?) • RF system • accelerating structure design • high-order mode analysis • impedance & wakefield calculations • longitudinal dynamics simulations MC Design Status- Y. Alexahin MAP meeting 03/02/2011

  5. 5 Task List - II • Beam-Beam & Collective Effects • incoherent beam-beam simulations • transverse impedance & wakefield calculations • coherent beam-beam modes stability • plasma beam-beam compensation (?) • Designs for Different Energies/Species • IR for 3 TeV c.o.m. collider • Higgs / Top Factory (?) • -p collider (?) • Highlighted items must be done by the end of 2011, • others by the end of 2012 MC Design Status- Y. Alexahin MAP meeting 03/02/2011

  6. 6 Effect on Chromatic Functions Wy Wy Dx Wx Wx Dipoles cut in short pieces with thin multipoles added Effect is strong but positive: Wy reduced by ~25%, easy to correct (just reduce strength of the 1st sext) MC Design Status- Y. Alexahin MAP meeting 03/02/2011

  7. 7 Effect on Dynamic Aperture 1024 turns DA, no beam-beam, reference emittance 10 mm mrad Strong effect on DA is baffling, explained by change in detuning coefficient MC Design Status- Y. Alexahin MAP meeting 03/02/2011

  8. 8 Sextupole Correction y Dx Quadratic effect dominates not allowing to reduce dQy/dEy x Corr. sext. MC Design Status- Y. Alexahin MAP meeting 03/02/2011

  9. 9 Octupole Correction of Detuning Octupoles (placed at the same locations) allow to reduce dQy/dEy and restore DA. Effects of higher order multipoles in IR dipoles are yet to be studied 1024 turns DA, no beam-beam, reference emittance 10 mm mrad MC Design Status- Y. Alexahin MAP meeting 03/02/2011

  10. 10 Fringe Field of IR quads (V.Kapin) y0 y0 x0 x0 1024 turns DA (MAD-X PTC) in units of initial coordinates atIP without (left) and with(right) quadrupole fringe field in hard-edge approximation. No beam-beam, Compare with the beam size of 6m at IP. MC Design Status- Y. Alexahin MAP meeting 03/02/2011

  11. 11 Fringe Field of IR quads (cont’d) Ey Ey Ex Ex DA in the plane of Courant-Snyder invariants. Compare with r.m.s. emittance of 3.5 nm. Fringe-field effect is strong but not forbidding (we know that from K.Oide). MC Design Status- Y. Alexahin MAP meeting 03/02/2011

  12. 12 * Tuning Section (Eliana) Dx y x Goal: vary * in a wide range w/o any change in Dx 6 conditions (on ,  and  in x, y) require 6 quads in a dispersion-free straight Is it possible to use this straight for halo removal? MC Design Status- Y. Alexahin MAP meeting 03/02/2011

  13. 13 Halo Removal Idea (Mokhov et al., 1998) Electrostatic deflector is too weak for TeV energies, is ~100 kV ~5 ns pulsed deflector feasible? MC Design Status- Y. Alexahin MAP meeting 03/02/2011

  14. 14 Induction Column (G.Caporaso et al.) Laser Optical fiber distribution system Proton source Focusing HGI SiC photoconductive switches Stack of Blumleins loaded on a central electrode (instead of a beam of particles) as a pulse source? Stack of “Blumleins” MC Design Status- Y. Alexahin MAP meeting 03/02/2011

  15. 15 Plans • Lattice design: - complete 1.5TeV design with tuning & collimation sections - develop 3TeV design • Fringe fields & Multipoles: - include realistic long. profile (Enge function) in MAD-X (F.Schmidt, CERN) or borrow from COSY-Infinity (V.Kapin) - nonlinear corrector arrangement for fringe field and multipole error correction (V.Kapin, F.Schmidt) • Strong-Strong Beam-Beam Simulations: - K.Ohmi (KEK) is willing to join with MAP - A.Valishev and E.Stern (FNAL) also promised to look • Self-Consistent Longitudinal Dynamics: - V.Balbekov & L.Vorobiev (FNAL GS) can address it (using ORBIT?) MC Design Status- Y. Alexahin MAP meeting 03/02/2011

  16. Final Focus Quads 11 Requirements adopted for this design:  full aperture 2A = 10sigma_max + 2cm (Sasha Zlobin wants + 1cm more)  maximum tip field in quads = 10T (G=200T/m for 2A=10cm)  bending field 8T in large-aperture open-midplane magnets, 10T in the arcs  IR quad length < 2m (split in parts if necessary!) a (cm) 5y 5x z (m) Gradient (T/m) 250 187 -131 -131 -89 82 Quench @ 4.5K 282 209 146 146 (with inner radius 5mm larger) Quench @ 1.9K 308 228 160 160 Margin @ 4.5K 1.13 1.12 1.12 Margin @ 1.9K 1.23 1.22 1.22  Is the margin sufficient? If not lower beam energy or increase * to allow for smaller aperture  We don’t need 5sigma+ half-aperture, 3sigma+ is enough: can accommodate N=50 m!  No dipole field from 6 to 16.5m, is it worthwhile to create ~2T by displacing the quads? MC Lattie Design - Y.Alexahin FNAL, November 11, 2009 MC Lattie Design - Y.Alexahin 3rd MCDW BNL December 3, 2009

  17. One More Innovation: the Arc Cell 5 Dx (m) SY SA SY SX DDx/5 SX x y  Central quad and sextupole SA control the momentum compaction factor and its derivative (via Dx and DDx) w/o significant effect on chromaticity  Large  -functions ratios at SX and SY sextupole locations simplify chromaticity correction  Phase advance 300/ cell  spherical aberrations cancelled in groups of 6 cells  Large dipole packing factor  small circumference (C=2.6 km with 9.2T dipole field) Now C=2.5 km with B=10T MC Lattice Update - Y. Alexahin NFMCC Meeting Oxford, MS, January 14, 2010

  18. Momentum Acceptance 6 x* Qx Qy y* p p p c Fractional parts of the tunes With 2 IPs the central tunes are 18.56, 16.58 - good (!) for beam-beam effect - good for the orbit stability and DA  Static momentum acceptance = 1.2%, while the baseline scheme calls for only 0.3%  Central value of themomentum compaction factor = -1.4510-5, can be made even smaller MC Lattice Update - Y. Alexahin NFMCC Meeting Oxford, MS, January 14, 2010

  19. Muon Collider Parameters 9 h z /  “Hour-glass factor” s (TeV) 1.5 3 Av. Luminosity / IP (1034/cm2/s) 1.25* 5 Max. bending field (T) 10 14 Av. bending field in arcs (T) 8.3 12 Circumference (km) 2.5 4 No. of IPs 2 2 Repetition Rate (Hz) 15 12 Beam-beam parameter / IP 0.087 0.087 * (cm) 1 0.5 Bunch length (cm) 1 0.5 No. bunches / beam 1 1 No. muons/bunch (1012) 2 2 Norm. Trans. Emit. (m) 25 25 Energy spread (%) 0.1 0.1 Norm. long. Emit. (m) 0.07 0.07 Total RF voltage (MV) at 800MHz 20230 + in collision / 8GeV proton 0.008 0.007 8 GeV proton beam power (MW) 4.8 4.3 ----------------------------------------------------------------------- *) With increase by the beam-beam effect P – average muon beam power (~  ) – beam-beam parameter • C – collider circumference (~  if B=const) • – muon lifetime (~ ) • * – beta-function at IP MC Lattice Update - Y. Alexahin NFMCC Meeting Oxford, MS, January 14, 2010

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