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Status and Perspectives of High Luminosity Flavour Factories

Status and Perspectives of High Luminosity Flavour Factories. M. E. Biagini, INFN/LNF EPS-HEP, Stockholm July 20 th 2013. Flavour Factories. Past: PEP - II @ SLAC, USA KEKB @ KEK, Japan Present: DA F NE @ INFN-LNF, Italy Vepp2000 @ BINP, Russia BEPCII @ IHEP, China Future :

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Status and Perspectives of High Luminosity Flavour Factories

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  1. Status and Perspectives of High Luminosity FlavourFactories M. E. Biagini, INFN/LNF EPS-HEP, Stockholm July 20th 2013

  2. Flavour Factories • Past: • PEP-II @ SLAC, USA • KEKB @ KEK, Japan • Present: • DAFNE @ INFN-LNF, Italy • Vepp2000 @ BINP, Russia • BEPCII @ IHEP, China • Future: • SuperKEKB @ KEK • Proposals: • Tau-Charm @ BINP, INFN, IHEP, TAC (Turkey)

  3. e+e- colliders Luminosity vsEnergy Super BF Linear CircularXbeam Super TC

  4. The past…

  5. PEP-II B-Factory 1999-2008

  6. KEKB B-Factory 1999-2010

  7. Integrated Luminosity

  8. KEKB tried “crab cavities” • Crab cavities installed in Feb. 2007 at KEKB and worked very well until the end of the KEKB operation • Highest luminosity with the crab cavities was about 23% higher than that before crab (prediction by bb simulation: ~100% increase) • Tuning with skew-sextupole magnets was effective to increase the luminosity with the crab cavity (~15% gain) • Found that skew-sextupoles are also effective to increase the luminosity when the crab cavities were switched off

  9. Recipes for success • Efficient injection system  Trickle injection • Tuning knobs  beam control • Strenuous instabilities fight  e-cloud mitigation, bunch-by-bunch feedbacks • Higher currents than design  see a) • New ideas (crab cavities, skew sextupoles) • Stable RF system • Powerful diagnostics  see b) • Skilled and expert staff

  10. Standard CollisionSchemeLimitations 1. Hourglass effect limits minimum IP b:by* ≤ sz 2. Bunch length reduction not advisable bunch lengthening, microwave instability, CSR 3. Further multibunch current increase would result in coupled bunch instabilities, HOM heating, higher wall-plug power 4. Higher emittances conflict with beamstay-clear and dynamics aperture limitations 5. Tune shifts saturate, beam lifetime drops due to beam-beam interactions

  11. Changing the approach… • Less than 10 years ago the “brute force” (increasing currents) was the only approach to higher luminosity • P. Raimondi (LNF) studied a new collision scheme with larger crossing angle and lower IP beam sizes (Large Piwinski Angle) PLUS a couple of sextupoles to twist the IP waist and cure x-y and synchro-betatron resonances raising from the angle (Crab Waist). Test at DAFNE • Adopted by all Factory projects after 2008 Oide, Progress of Theoretical Physics, Vol. 122, No. 1, July 2009

  12. CrabWaistAdvantages • Luminosity gain with N • Verylowhorizontaltuneshift • Vertical tuneshiftdecreases with oscillationamplitude • Large Piwinski’s angle • F = tg(q/2)sz/sx • 2. Vertical beta comparable • with overlap area • by 2sx/q 3. Crabwaisttransformation • y = xy’/q • Geometricluminosity gain • Lower verticaltuneshift • Suppression of verticalsynchro-betatronresonances • Geometricluminosity gain • Suppression of X-Y betatron and synchro-betatronresonances

  13. ....and besides… • No need to increaseexcessivelybeamcurrent and to decrease the bunchlength: • Beaminstabilities are less severe • Manageable HOM heating • No coherentsynchrotronradiation of short bunches • No excessivepowerconsumption • Problem of parasiticcollisionsautomaticallysolved due to highercrossing angle and smallerhorizontalbeamsize • Lesshourglassby* can be decreased

  14. Crab sextupoles effect • Crab sextupoles are strong and introduce large non-linearity, optics between them has to be linear as much as possible • Dynamic Aperture is greatly reduced. Solutions: • Design IP doublet so to compensate the kynematic (octupole) and fringing field effects • Locally compensate the chromaticity (Y and X separately) • Add octupoles and additional sextupoles to compensate for the aberrations induced by the off-phase sextupoles • Adjust b and phase advance between crab sextupoles • Done for SuperB and Italian Tau/Charm: effect is reduced (not cancelled)

  15. Design & operation challenges • Ultra low emittances (H, V)  Coupling compensation • Interaction Region and Final Focus design (Low b*, IP quadrupoles) • Dynamic aperture (with fringing fields in IP quads and crab sextupoles) • Tolerances to machine errors and vibrations  Low Emittance Tuning • Impedance budget • Lifetimes (bb bremsstrahlung, Touschek)  trickle charge injection • High backgrounds  detector protection • High beam currents  injection system • Extreme vacuum with high currents • Short bunch distance  kickers, feedbacks • Instabilities control (collective effects, b-by-b feedbacks) • Adequate diagnostics (SLM, BPM, BLM, b-by-b luminosity monitor…) • On-line tuning knobs  orbit, IP waist, dispersion, coupling, IP b, tunes, IP angles • ….

  16. Synergies • Most of the above topics (except for high beam currents and beam-beam issues) apply to modern design of 4th generation Synchrotron Light Sources • Low emittance tuning techniques (LOCO, LET, …) successfully applied • Record emittances measured at Diamond, SLS, ASLS (ey < 2 pm) • Dynamic Aperture optimization techniques (MOGA, FMA, …) give larger momentum and transverse acceptances • The two communities actively collaborate (see for example 3rdLOWeRING Workshop at Oxford, EuCARD2) http://www.physics.ox.ac.uk/lowemittance13/index.asp

  17. The present…

  18. DAFNE @ INFN-Frascati • First F-Factory with Large Piwinski Angle and Crab Waist collision scheme (adapted to previous IR design) • 3xLuminosity boost with non magnetic detector SIDDHARTA • Proven effectiveness of crab sextupoles (very good agreement with numerical predictions and simulations) • New Interaction Region for KLOE2 magnetic detector • Limited in beam currents (e-cloud, damaged bellows, short lifetime), but… • …e-cloud clearing electrodes successful in increasing threshold, and… • ..lot of work in 2013 for replacement/upgrade of old hardware in progress  resume operation by this Summer

  19. Effect of crab waist scheme Design Goal CRAB ON CRAB OFF

  20. Comparison of best runs with and without Crab-Waist Luminosity [1028 cm-2 s-1] Luminosity [1028 cm-2 s-1]

  21. VEPP-2000, BINP, Round Beams

  22. Round Beams Collisions • Round beams experiment: • geometrical factor gain • beam-beam limit enhancement • 2 pairs of superconducting focusing solenoids in the 2 Interaction Regions symmetrically with respect to IPs • Several combinations of solenoid polarities satisfy Round Beams condition: • “Normal Round” (++ --) • “Möbius” (++ -+) • “Double Möbius” (++ ++) • Two “Flat” combinations (+- +- or +- - +) more simple and also satisfy RBC if the betatron tunes lie on the coupling resonance • n1- n2 = 2 • Small Dynamic Aperture

  23. Luminosity vs Energy Lack of e+ DA and IBS lifetime Flip-flop Simulations VEPP-2M data 2010-2011 run,2011-2012 run,2012-2013 run

  24. BEPC-II, IHEP • Major upgrade of BEPC in 2004 • Presently only existing t/charm

  25. Luminosity tuning • Luminosity increased nx 0.5 • Low ap lattice  lower e and sz

  26. The near Future…

  27. Upgrade to Belle II detector Colliding bunches New superconducting final focusing magnets near the IP e+ 3.6A e- 2.6A KEKB to SuperKEKB Redesign the lattice to squeeze the emittance (replace short dipoles with longer ones, increase wiggler cycles) • Nano-Beam scheme • extremely small by* • low emittance • Beam current double Reinforce RF systems for higher beam currents Replace beam pipes with TiN-coated beam pipes with antechambers 40 times higher luminosity 2.1x1034 --> 8x1035 cm-2s-1 Improve monitors and control system Injector Linac upgrade Upgrade positron capture section DR tunnel Low emittance RF electron gun New e+ Damping Ring K. AKAI, Progress in Super B-Factories, IPAC13

  28. Parameters of KEKB and SuperKEKB Intra-beam scattering is included. K. AKAI, Progress in Super B-Factories, IPAC13

  29. Final focus SC quads (QCS) • Eight final focus QCS with 40 corrector coils are to be used. • Fabrication of QCS-L started in July 2012, and will be completed in JFY2013. • Fabrication of QCS-R is scheduled in JFY2013 and 2014. • Prototype magnet was made at KEK. Test results show sufficient margin for operation. • Corrector coils are being wound at BNL under BNL/KEK collaboration. QC1LE prototype magnet Successfully tested without any quench up to 2157A, well over the design current (1560A) for nominal operation. I4S/Ic@4.7K = 62.8% I12GeV/Ic@4.7K = 87.0% Sufficient margin for operation K. AKAI, Progress in Super B-Factories, IPAC13

  30. Commissioning Scenario Commissioning Scenario Baseline Scenario Phase 1 Jan. 2015 - ~5 months Phase 2 ~4 months Phase 3 First target luminosity 1 x 1034 cm-2s-1 TOP CDC PXD/SVD ready installation [Phase 1] No QCS, No Belle II • Basic machine tuning, Low emittance tuning • Vacuum scrubbing ( 0.5 ~ 1.0 A, >1 month) • DR commissioning start (~Apr. - ) [Phase 2] With QCS, With Belle II (without Vertex Detector) • Small x-y coupling tuning, Collision tuning • by* will be gradually squeezed • Background study [Phase 3] With Full Belle II • Increase beam current with adding more RF • Increase luminosity K. AKAI, Progress in Super B-Factories, IPAC13

  31. The possible Future…

  32. Super t/charm proposals

  33. Italian t/Charm Factory • Evolution after cancellation of SuperB • Energy tunable in the range Ecm = 1-4.6 GeV • 1035cm-2 s-1luminosity at the t/charm threshold and upper • Symmetric beam energies • Longitudinal polarization in the electron beam (60-70%) • Possibility of e-e- collisions (to be studied) • Design based on “Large Piwinski angle & crab waist sextupoles” collision scheme • Low beam emittance (about 2 nm natural) • Wigglers needed at lower beam energy • Injection system scaled from the SuperB one • Possibility to use injection Linac + additional C-band Linac for a 6 GeV SASE-FEL facility

  34. t/charm parameters vs E

  35. t/charm @Tor Vergata (former SuperB site) Tau/Charm Accelerator Report just written (150 pp, not public yet)

  36. Summary • Higher luminosity colliders can still be built, profiting from: • experience from past successes • new ideas • new technologies • synergy with other communities • A Super Factory is being built at KEK  very important to keep alive this kind of Accelerators and Physics ! • Several proposal for lower energy High Luminosity Flavour Factories on the market at different laboratories with experience of successful accelerators

  37. Aknowledgments • For the material presented here I’m indebted with: • K. Akai, Y. Funakhoshi, KEK • Q. Qing, Y. Zhang, IHEP • M. Zobov, INFN-LNF • A. Bogomiagkov, I. Koop, D. Schwartz, BINP THANK YOU FOR YOUR ATTENTION

  38. Spare slides

  39. Beam energy from 0.5 to 2.1 GeV • Peak luminosity 1035 cm-2s-1 at 2 GeV and within as wide as possible energy range • Circumference 366 m to fit in the existent tunnel of VEPP4-M (previous design 800m) • Conform as much as possible to existent infrastructure • Longitudinal polarization at some energy points BINP Super cTau (2nd design)

  40. Parameters Old C-Tau, 800m 2 cm / 0.76 mm 10 nm 10 mm 7·1010 1.7 A

  41. IHEP Super Tau-Charm Factory • Dual ring, factory like • 2.5-3 GeV, parasitic 3rd generation SR source • Crab Waist collision scheme • Small IP b functions • Small emittance using wigglers • High beam current • Electron beam polarization (e- source, 5 Siberian Snakes) • Top-up injection at 3 GeV, 50 Hz

  42. IHEP Super Tau-Charm Factory

  43. Turkish Accelerator Complex (TAC) SCF • TAC SCF presented to ECFA 2011 • Linac (e-) + ring (e+) charm factory with L= 1.41035 cm-2 s-1 • Synchrotron light source based on positron ring • Free electron laser based on electron linac • TDR SCF@TAC will be completed in 2013

  44. TAC Super Charm Factory parameters

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