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LEP3 Machine Design Options

c ern.ch/ accnet. LEP3 Machine Design Options. Frank Zimmermann LEP3 Day, 18 June 2012. w ork supported by the European Commission under the FP7 Research Infrastructures project EuCARD, grant agreement no. 227579. LEP3 history in a nutshell.

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LEP3 Machine Design Options

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  1. cern.ch/accnet LEP3 Machine Design Options Frank Zimmermann LEP3 Day, 18 June 2012 work supported by the European Commission under the FP7 Research Infrastructures project EuCARD, grant agreement no. 227579

  2. LEP3 history in a nutshell • “LEP3” idea raised by Alain Blondel at Grenoble EPS-HEP ECFA session in July 2011 • LEP3 paper with beam parameters submitted to arXiv on Christmas’ Eve 2011 • “SuperTRISTAN” proposals by KatsunobuOide in January/February 2012 • LEP3 was a parenthesis at Chamonix’12 • Lots of interest in LEP3 poster at IPAC’12 • 18 June 2012: first LEP3 day

  3. LEP3 at IPAC’12

  4. LEP3 circular Higgs factory (ee-> ZH) key parameters beam energy: ≥120 GeV luminosity in each of two experiments: ≥ 1034 cm-2s-1 at the ‘Higgs energy’ (~240 GeV c.m.) ≥ 1035 cm-2s-1 at 2xMW (~160 GeV c.m.) ≥ 5x1035 cm-2s-1 at the Z pole (~90 GeV c.m.)

  5. two options • installation in the LHC tunnel “LEP3” + inexpensive (<0.1xLC) + tunnel exists + reusing ATLAS and CMS detectors + reusing LHC cryoplants - interference with LHC and HL-LHC • new larger tunnel “DLEP” or “TLEP” + higher energy reach + decoupled from LHC and HL-LHC operation and construction + tunnel can later serve for HE-LHC (factor 2-3 in energy from tunnel alone) with LHC remaining as injector - 3-4x more expensive (new tunnel, cryoplants, detectors?)

  6. LEP3 double ring A. Blondel Sketch of LEP3 double ring [1]: a first ring accelerates electrons and positrons up to operating energy (120 GeV) and injects them at a few minutes interval into the low-emittance collider ring, which includes high luminosity 1034 cm-2 s-1 interaction points.

  7. LHC tunnel cross section with space reserved for a future lepton machine like LEP3 [blue box above the LHC magnet] and with the presently proposed location of the LHeC ring [red]

  8. LEP3 key parameters • arc optics • same as for LHeC:ex,LHeC<1/3 ex,LEP1.5 at equal beam energy, • optical structure compatible with present LHC machine • small momentum compaction (short bunch length) • assume ey/ex ~5x10-3 similar to LEP (ultimate limit ey ~ 1 fm from opening angle) • RF • RF freqeuncy 1.3 GHz • ILC-type RF cavities high gradient (20 MV/m assumed, 2.5 times LEP gradient) • total RF length for LEP3 at 120 GeV similar to LEP at 104.5 GeV • short bunch length (small b*y) • cryo power <1/2 LHC • synchrotron radiation • energy loss / turn: Eloss[GeV]=88.5×10−6 (Eb[GeV])4 /ρ[m]. • higher energy loss than necessary • arc dipole field =0.153 T • compact magnet • critical photon energy = 1.4 MeV • 50 MW per beam (total wall plug power ~200 MW ~ LHC complex)→4x1012 e±/beam

  9. LHeC Conceptual Design Report M. Klein

  10. LEP3/DLEP parameters in comparison -1

  11. LEP3/DLEP parameters in comparison -2

  12. IR design large aspect ratio sx/sy ~200 to limit beamstrahlung • b*y ~ 1 mm: • close to the value giving the maximum geometric luminosity for sz ~ 2-3 mm (hourglass effect); • realized by • short free length from the IP, l* ~ 4 m • quadrupolelength ~ 4 m • quadrupole gradient ~17 T/m • and aperture (radius) ~5 cm (>20σy)

  13. J. Nash CARE-HHH IR’07 quadrupoles inside CMS? Had Barrel: HB Had Endcaps:HE Had Forward: HF The important regions for forward jet tagging are in HE/HF HO HB HE HF z=4.0-10.0 m Rmax≥40 cm 14.3 m 10.8m 6.5 m 3.0 m

  14. M. Nessi CARE-HHH IR’07 quadrupoles inside ATLAS? z=3.49-4.58 m rmax=18 cm z=6.8-8.66 m rmax=43 cm z=8.69-12.870 m rmax=87 cm z=12.95-18.60 m rmax=150 cm

  15. bunch intensity limits beam-beam tune shift up to ~0.1 OK (see talk by R. Assmann) TMCI LEP2: limit of 5x1011 at 22 GeV injection LEP3: gain factor 5.5 from higher energy; lose factor (1.3/0.7)3 from wake field (different RF frequency); gain factor >2 from larger Qs [other: b functions at RF, bunch length?] => Nb~1012OK; 4 bunches per beam

  16. beam lifetime • LEP2: • beam lifetime ~ 6 h • dominated by radiativeBhahba scattering with cross section s~0.215 barn [11] • LEP3: • with L~1034 cm−2s−1 at each of two IPs: • tbeam,LEP3~16 minutes • additional beam lifetime limit due to beamstrahlung > 30 minutes if dmax,RF ≥ 4% • (see talk by Marco Zanetti)

  17. beamstrahlung formulae Upsilon parameter P. Chen, K. Yokoya [7] photons emitted per collision average energy loss per collision rms energy spread per collision K. Yokoya [8] for LEP3 the longitudinal damping time is 17 turns and the number of collisions per damping time 34

  18. RF momentum acceptance synchronous phase overvoltage momentum acceptance

  19. e+ production rate top-up interval << beam lifetime → average luminosity ≈ peak luminosity! for the top-up to work: we need about 4×1012e+ every few minutes, or of order 2×1010e+per second for comparison: LEP injector complex delivered of order 1011e+ per second [12]

  20. ramping speed of accelerator ring nominal ramp rate of LEP: 500 MeV/s [13] at the same speed acceleration to 120 GeV would take less than 4 minutes this would be sufficient, but faster ramp rate would be even better for maintaining a constant luminosity

  21. two ambitious time schedules

  22. LEP3 robustness & novelties • storage-ring colliders: well-established, robust technology • novel features of LEP3: • 15% more energy than LEP2 • top-up injection • ultralow vertical b* (but still 3-4 x SuperB) • significant beamstrahlung

  23. LEP3 R&D • 3-D integration in LHC tunnel & cohabitation with HL-LHC and LHeC; RF integration; • beam dynamics studies and optics design for the collider ring; HOM heating w. large bunch currents and short bunch lengths; vertical emittance tuning, single-bunch charge limits, longitudinal effects for Qs~ 0.35, low beta insertion with large momentum acceptance, parameter optimization, beam-beam effects, including beamstrahlung, and top-up scheme • optics & beam dynamics for accelerator ring • magnets: collider-ring dipole magnet, acc.-ring dipole, and low-beta quad.; • 100 MW SR effects • SRF & cryogenics; optimum RF gradient & RF frequency; • engineering study of new larger tunnel for DLEP or TLEP • cost and performance comparison double vs single ring; • injector complex, including e+ source • dual use LEP3 and LHeC • MDI; integration of warm low-beta quadrupolesinside ATLAS & CMS • detector performance and upgrade studies • LEP3 physics studies • Synergies: LHeC, HP-SPL, XFEL, HE-LHC

  24. conclusions& questions circular Higgs factory with 240 GeV c.m. and L~1034 cm-2s-1 appears possible in the LHC tunnel or in a larger tunnel both LEP3 and/or DLEP/TLEP look feasible is such machine important for particle physics? - going much beyond 120 GeV looks challenging, in particular in the LHC tunnel - how critical are H-H-Z production & t-t studies? which of the two options is more realistic/preferred? can LEP3/DLEP wait until after the HL-LHC (~2035)?

  25. LEP3 2011 LEP3 on LI, 2012 SuperTristan 2012 LEP3 in Texas, 2012 circular Higgs factories become popular around the world

  26. References: [1] A. Blondel, F. Zimmermann, ‘A High Luminosity e+e- Collider in the LHC tunnel to study the Higgs Boson,’ V2.1-V2.7, arXiv:1112.2518v1, 24.12.2011 [2] C. Adolphsen et al, ‘LHeC, A Large Hadron Electron Collider at CERN,’ LHeC working group, LHeC-Note-2011-001 GEN. [3] H. Schopper, The Lord of the Collider Rings at CERN 1980- 2000, Springer-Verlag Berlin Heidelberg 2009 [4] K. Oide, ‘SuperTRISTAN - A possibility of ring collider for Higgs factory,’ KEK Seminar, 13 February 2012 [5] R.W. Assmann, ‘LEP Operation and Performance with Electron-Positron Collisions at 209 GeV,’ presented at 11th Workshop of the LHC, Chamonix, France, 15 - 19 January 2001 [6] A. Butterworth et al, ‘The LEP2 superconducting RF system,’ NIMA Vol. 587, Issues 2-3, 2008, pp. 151 [7] K. Yokoya, P. Chen, CERN US PAS 1990, Lect.Notes Phys. 400 (1992) 415-445 [8] K. Yokoya, Nucl.Instrum.Meth. A251 (1986) 1 [9] K. Yokoya, ‘Scaling of High-Energy e+e- Ring Colliders,’ KEK Accelerator Seminar, 15.03.2012 [10] V. Telnov, ‘Restriction on the energy and luminosity of e+e- storage rings due to beamstrahlung,’ arXiv:1203.6563v, 29 March 2012 [11] H. Burkhardt, ‘Beam Lifetime and Beam Tails in LEP,’ CERN-SL-99-061-AP (1999) [12] R. Bossart et al, ‘The LEP Injector Linac,’ CERN-PS-90-56-LP (1990) [13] P. Collier and G. Roy, `Removal of the LEP Ramp Rate Limitation,’ SL-MD Note 195 (1995).

  27. thanks to: • Alain Blondel for getting me involved in this exciting project and for organizing a LEP3 BBQ tonight! • Katsunobu Oide for his interest and excellent ideas • Mike Koratzinos for many stimulating discussions • Kaoru Yokoya and Valery Telnov for pointing out the • importance of beamstrahlung • Marco Zanetti for addressing the beamstrahlung issue • all speakers and participants of the LEP3 day • Andrzej Siemko for lending us a piece of LEP2 beam pipe • Steve Myers and Jean-Pierre Koutchouk for supporting • the initiative

  28. recruiting an SRF expert for LEP3? thank you for your attention!

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