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An SLC-Style Higgs Factory (and some comments on NLC technology)

An SLC-Style Higgs Factory (and some comments on NLC technology). Tor Raubenheimer. ICFA Higgs Factory Workshop November 14 th , 2012. Goal and Outline. Can we reduce ILC cost by factor of 4 and still do physics? What about a gamma-gamma collider?

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An SLC-Style Higgs Factory (and some comments on NLC technology)

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  1. An SLC-Style Higgs Factory(and some comments on NLC technology) Tor Raubenheimer ICFA Higgs Factory Workshop November 14th, 2012

  2. Goal and Outline • Can we reduce ILC cost by factor of 4 and still do physics? • What about a gamma-gamma collider? • Eliminate complicated damping rings, e+ source and lowers energy • What about the SLC configuration? • Further reduce center-of-mass (cms) energy to ~85 GeV 500 GeV ILC RDR Cost Distribution 10% 5% 8% Higgs Factory Workshop, 11/14/12

  3. Synchrotron Radiation Limitations • Very strong synchrotron radiation presents severe limitation on center-of-mass energy in SLC configuration DE ~ 6 GeV / turn at 85 GeV with 1-km radius sDE/E ~ 0.2% / turn at 85 GeV with 1-km radius Dge ~ 1 mm-mrad / turn at 85 GeV with 1-km radius and 5-m cell Requires ~3.5 km radius at 240 GeVcms Higgs Factory Workshop, 11/14/12

  4. Gamma-Gamma Higgs Factory Concept • Lots of people have discussed a g-g Higgs factory • Significant write-ups for NLC ZDR, TESLA and ILC • Good discussion from D. Asner (2001), arXiv:hep-ex/0111056 • Polarized e-/e- beams and intense lasers becoming more realistic • SAPPHIRE design paper is a good reference • S. Bogacz, et. al., arXiv:1208.2827[physics.acc-ph] (2012). • Advances in tapered FELs makes laser sources more reasonable Higgs Factory Workshop, 11/14/12

  5. Gamma-gamma collider • Lack of beamstrahlung allows different optimization of LC parameters  focus on high charge, round beams Relaxes location of conversion point, jitter tolerances, etc From an rfgun emittance tends to scale as less than N  gain by going to higher charge Higgs Factory Workshop, 11/14/12

  6. Inverse Compton Scattering • Inverse Compton Physics • x = 4.8 to avoid pair production llaser ~ 350 nm and wm ~ 0.8 E0 implying 80 GeV e- beams for 130 GeVcmsg-g • Need 1.2 J per laser pulse in 1-ps and a 1 um spot 4 mm from IP to get 80% conversion Higgs Factory Workshop, 11/14/12

  7. Laser Beam Source • Significant progress in optical cavities but UV is more difficult • Seeded FEL’s have demonstrated strong tapering G.Klemz, et al (2005), arXiv:physics/0507078 • Recent seeding studies in hard x-ray regime • support simulation studies • J-class pulses are thought possiblewith ~10% extraction efficiency SASE + Taperingat 10cm wavelength • T. Orzechowski et al. PRL (1986) Higgs Factory Workshop, 11/14/12

  8. Polarized Rf Gun • Have to get rid of the damping rings because they are expensive and have very poor longitudinal emittance causing expensive bunch compression system • DR’s plus BC’s are ~20% of ILC cost! • SCRF gun development has made great progress. Options at frequencies from 112 MHz up to 1.3 GHz • 704 MHz gun is designed for 5 nCat 5 mm-mrad • Lower frequency would likely be better for high bunch charges • Simulations of 5 mm-mradat 10 nC with 112 MHz gun 112 MHz QWT SCRF gun

  9. Acceleration Limitations • Sapphire assumes a 4x recirculation in two 11 GeV CW linacs an average current of 0.32 mA and an average gradient of 10 MeV/m and a 200 kHz bunch rate • Jlab model for the linacs 25 MW per beam! • Another option is the ILC SCRF scheme using KEK-style couplers, 10 mA beam current at the IP (40 mA in the linac), a 45 GeVlinac with 2x recirculation (some issues here) and a 10Hz rep. rate or a single pass in an 85 GeVlinac with 20 mA • ILC model for the linacs 7 MW per beam and recover luminosity with collision format Higgs Factory Workshop, 11/14/12

  10. High Power Coupler Design • Linac current limited by couplers. KEK large aperture coupler design has higher power capability. TRISTAN type ceramic window Monitor Port Beam Pipe 82.4 mm 5K Low loss 0.2W to 5K Higher Static loss 1W to5K No Tuning Warm Window Cold Window 80K Vacuum Port Qext = 2.0 x 106 Prf = 350 kW Higgs Factory Workshop, 11/14/12

  11. Arcs Considerations • Strongly limited by synchrotron radiation • Biggest impact is on beam emittance • Could consider high brightness lattices like light sources • TME lattice has minimum emittance of:but one problem is poor lattice packing • Requires ~600 cells with 11 kG bends and Fm ~ 25% tokeep Dge ~ 10% Higgs Factory Workshop, 11/14/12

  12. Arc Considerations (2) • Another option is a combined function lattice similar to SLC • 1 km average bending radius with Dge ~ 5e-7 • 4.5 meter cell with 2 meter bends  roughly 700 cells • B’ ~ 14 kG/cm; B0 ~ 3.2 kG • Not clear if this wouldbe cheaper and simpler than TME-style lattice Higgs Factory Workshop, 11/14/12

  13. SLC-ILC-Style (SILC) Higgs Factor • Some challenges with 2-pass design! 45 GeV, 1.5 kmor 85 GeV, 3 km 250 m 1 km radius Final focii ~ 300 meters in length Laser beam from fiber laser or FEL Upgrade with plasma afterburners (what cms energy is possible?) Higgs Factory Workshop, 11/14/12

  14. Primary Parameters Higgs Factory Workshop, 11/14/12

  15. Upgrade with Plasma Afterburner • The goal is to upgrade the Higgs machine in energy using PWFA afterburner to double beam energy. • Could also increase electron beam energy 80  100 GeV from the arcs. Would require a more complex arc cell like a TME optics. Alternately would be to develop a shaped bunch for higher transformer ratio! • Challenging to achieve desire luminosity. Simple idea would be divide bunch 2/3 = drive, 1/3 = production but luminosity drops by 4.5. Looking at other approaches to boost energy. Higgs Factory Workshop, 11/14/12

  16. Plasma Wakefield Afterburner Erik Adli Higgs Factory Workshop, 11/14/12

  17. Cost Guestimate • Assumptions: • Laser system is donated by LLNL! • Linac costs scaled from ILC costs • Arc costs scaled from ILC and SLC • 45 GeVlinac versus 490 GeV(rf power increases by 4x but small % of linac costs)  20%or 0.8 B$ value • BDS reduced in half  0.2 B$ • DR, RTML, and e+ = 0 • Rf gun = 0.05 B$ value • Arc = 2km C&C tunnel and8 km of arc magnets & vacuum(100 k$ / meter beamline or 40 k$ / meter in value units) • 0.4 B$ value • Other costs ~ 0.15 B$ •  1.6 B$ value ~25% ILC 500 GeV ILC RDR Cost Distribution 10% 5% 8% Higgs Factory Workshop, 11/14/12

  18. Summary – SLC-style linear collider • SLC-style option (arcs) is very limited by synchrotron rad. • Options include 80 GeV beams with 1 km radius, 120 GeV beams with 3.5 km radius, … • A combination of the SLC LC concept with ILC technology, gamma-gamma and high power lasers/FELs may provide a cost effective and politically acceptable path to a Higgs factory. • It would engages almost all partners with: • Challenging beam dynamics (everybody), • High power SCRF (Cornell and FNAL), • SCRF guns (BNL), • Lasers (LLNL, LANL and SLAC), • Recirculatinglinacs (Jlab), • and physics (the world)! Higgs Factory Workshop, 11/14/12

  19. NCRF versus SCRF? • NCRF is believed (at least be me) to be cheaper per GeV • Costs are not fully developed and industrialization scaling is guess • Fabrication infrastructure can be developed quickly as demonstrated by Fermilab in early 2000’s • SCRF is cheaper per MW • Solid cost basis from XFEL • Major investments in fabrication infrastructure in US (200 M$), Asia and Europe • SCRF LC has large zero energy cost due to large injector complex • PWFA concept is still attractive but do not yet understand infrastructure costs  comparable to NCRF Higgs Factory Workshop, 11/14/12

  20. Simplified Layout of NLC/GLC RF System (Efficiencies & Powers in Parentheses) Beam / Wall Plug = 6.5%

  21. 1 3 2 X-Band Pulse Compression Revisited! 526 kV, 1.08 kA, 600 ns 485 MW600 ns Dual-moded transmissive delay line. →No tuning needed (use LLRF phase). → Intrinsic efficiency is 100%. CP TE12 (340 MW) Cr = 3 hi = 1 1 unit delay (200 ns) TE01 (680 MW) ~30 m 3340 MW200 ns • Four klystrons are combined through a cross potent superhybrid. • During the 1st time bin, power combines through path 1 into the delay line. • Upon returning through the second pipe of the delay line, the power is combined with that of the 2nd time bin, coming along path 2, and sent through the delay line again in a different mode. • The returning power is then split and feeds the accelerator simultaneously with the 3rd time bin power directed along path 3. C. Nantista ’08

  22. Delay Line Packing If the efficiency of the PC/PDS is 90%, we have ~918 MW / RF system. If the accelerating structure power requirement is 100 MW/m and the packing fraction is 90%, we can then feed ~10 m* of the linac physical length per RF system. Delay lines from 3 RF stations will overlap, for a cross-sectional footprint of 6 pipes. * fifteen 60cm structures. Comparison With Dual-Moded SLED-II 6.7% more klystrons (@ 113% peak power & 75% pulse width) 47% fewer modulators (@ 105% voltage, 216% current & ~173% pulse energy) 6.7% more delay line (with no moving tuners!) Intrinsic compression efficiency: 1 vs. 0.86 Higgs Factory Workshop, 11/14/12

  23. NCRF versus SCRF layouts and costs ILC RDR Costs 31 km for 500 GeV

  24. Simplified/Unified ILC and NLC Linac Costs NLC damping rings and sources significantly less expensive than ILC 300 meter versus 3000 meter circumference; 2 GeV versus 5 GeV, etc. Higgs Factory Workshop, 11/14/12

  25. 1 TeV PWFA • Concept for PWFA-based on LC developed in 2009 • Options for NCRF or SCRF drive linac • No optimization; cost dominated by turn-around arcs • Re-optimize to lower turn-around energy or co-linear layout

  26. Summary – NCRF Options • NCRF may be more cost effective than SCRF for a low energy (Higgs Factory) LC • In general SCRF has greater capability than NCRF but the higher power capability may not be necessary for LC • World (HEP) accelerator community is developing SCRF as next generation accelerator technology • Light source community is more driven by cost limitations • Topic may be re-examined if a project is formed but hard to make progress at this time Higgs Factory Workshop, 11/14/12

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