SuperB: a 10 36 cm -2 s -1 accelerator

1. SuperB Accelerator& ILCM. E. Biagini, LNF-INFNfor the SuperBTeamILC GDE visit, LNF, Jan. 22th 2008 D. Alesini, M. E. Biagini, R. Boni, M. Boscolo, A. Drago, S. Guiducci, G. Mazzitelli, M. Preger, P. Raimondi, S. Tomassini, C. Vaccarezza, M. Zobov (INFN/LNF, Italy) K. Bertsche, Y. Cai, A. Fisher, S. Heifets, A. Novokhatski, M.T. Pivi, J. Seeman, M. Sullivan, U. Wienands, W. Wittmer (SLAC, US) T. Agoh, K. Ohmi, Y. Ohnishi (KEK, Japan) I. Koop, S. Nikitin, E. Levichev, P. Piminov, D. Shatilov (BINP, Russia) G. Bassi, A. Wolski (Cockcroft, UK) M. Venturini (LBNL, US) S. Bettoni (CERN, Switzerland) Variola (LAL, France) E. Paoloni, G. Marchiori (Pisa Univ., Italy)

2. SuperB: a 1036 cm-2 s-1 accelerator • SuperB is an international enterprise aiming at the construction of a very high luminosity (1036 cm-2 s-1) asymmetric e+e- Flavor Factory, with location at the campus of the University of Rome Tor Vergata, near the INFN Frascati National Laboratory • Aims: • Very high luminosity • Desire 1036: experimenters say 1035 will not get to the physics soon enough. • High reliability • The goal is integrated luminosity! • Polarized e- at IP • This is a relatively new addition by the users. • Ability to collide at Y4S and lower energy (~J/Psi) • For maximum number of experimenters. • A Conceptual Design Report, signed by 85 Institutions was published in March 2007 (arXiv:0709.0451 [hep-ex])

3. Accelerator basic concepts (1) • B-Factories (PEP-II and KEKB) have reached high luminosity (>1034 cm-2s-1) but, to increase L of ~ 2 ordersof magnitude, bordeline parameters are needed such as: • Very high currentsHOM in beam pipe • overheating, instabilities, power costs • detector backgrounds increase • Very short bunchesRF voltage increases • costs, instabilities • Smaller damping timesWiggler magnets • costs, instabilities • Crab cavities for head-on collision • KEKB experience Difficult and costly operation

4. Basic concepts (2) Accelerator basic concepts (2) • SuperB exploits an alternative approach, with a new IP scheme: • Small beams (ILC-DR like) • very low emittances, ILC-DR R&D • Large Piwinsky angle and “crab waist” with a pair of sextupoles/ring (F = tg(q)sz/sx) • interaction region geometry • Currents comparable to present Factories • lower backgrounds, less HOM and instabilities Requires a lot of fine machine tuning Small collision area: sx/q

5. Ultra-low emittance Very small b*at IP Large crossing angle “Crab Waist” transformation Small collision area Lower b*ispossible NO parasitic crossings NO x-y-betatron resonances A new idea for collisions Thigher focus on beams at IP and a “large” crossing angle (large Piwinski angle) + use a couple of sextupoles/ring to “twist” the beam waist at the IP Already proved at DAFNE 1. P.Raimondi, 2° SuperB Workshop, March 2006 2. P.Raimondi, D.Shatilov, M.Zobov, physics/0702033

6. Relatively easier to makesmall sxwith respect toshort sz Problem ofparasitic collisionsautomatically solved due to higher crossing angle and smaller horizontal beam size There is no need to increase excessively beam current and to decrease the bunch length: Beam instabilities are less severe Manageable HOM heating No coherent synchrotron radiation of short bunches No excessive power consumption and...

7. How it works Crab sextupoles OFF: Waist line is orthogonal to the axis of other beam All particles in both beams collide in the minimum by region, with a net luminosity gain Crab sextupoles ON: Waist moves parallel to the axis of other beam: maximum particle density in the overlap between bunches Plots by E. Paoloni

8. Example of x-y resonance suppression D.Shatilov’s (BINP), ICFA08 Workshop Much higher luminosity! Crab Waist On: 1. large Piwinski angleF >> 1 2.bycomparable withsx/q Typical case (KEKB, DAFNE): 1. low Piwinski angleF< 1 2.bycomparable withsz

9. Comparison of SuperB to Super-KEKB IP beam distributions for KEKB IP beam distributions forSuperB

10. SuperB main features • Goal: maximize luminosity while keeping wall power low • 2 rings (4x7 GeV) design: flexible but challenging • Ultra low emittance optics: 7x4 pm vertical emittance • Beam currents: comparable to present Factories • Crossing angle and “crab waist” used to maximize luminosity and minimize beam size blow-up • Presently under test at DAFNE • No “emittance” wigglers used in Phase 1 (save in power) • Design based on recycling PEP-II hardware (corresponds to a lot of money) • Longitudinal polarization for e- in the HER is included (unique feature)

11. Lattice overview (1) • The lattice for SuperB rings needs to comply with several issues: • small emittances • asymmetric energies • insertion of a Final Focus (similar to ILC), with very small b* • large dynamic aperture & long lifetimes • spin rotator section in HER • The new large crossing angle & small collision parameters scheme with “crab waist”has relaxed the requests on the bunch lengths and beam currents • Main objective is to design a lattice that can deliver 1x1036 luminosity while keeping wall power requirements as low as possible

12. Lattice overview (2) • First design was derived by ILC-DR OCS lattice with TME cells and ILC-like Final Focus, but shorter rings • Then a solution using the PEP-II hardware and smaller intrinsic emittance (higher x-phase advance in a cell) was designed • The present layout has small emittances (1.6 nm/4 pm (HER x/y) and 2.8 nm/7 pm (LER x/y)) and 20 msec longitudinal damping times without insertion of wiggler magnets • However space is provided for wiggler installations whenever needed (ex. luminosity upgrade option)

13. Ring optical functions LER Öb HER Öb No spin rotator here

14. SuperB design challenges • Beam beam • high tune shift • strong-strong simulations for large crossing angle • effect of tolerances and component errors • Low emittance • tolerances • achieving vertical emittance • tuning and preserving • vibrations • IR design • 50 nm IP vertical beam size • QD0 design • luminosity backgrounds • Polarization • impact on lattice • depolarization time • impact on beam-beam • continous injection • Lattice • dynamic aperture with crab sextupoles and spin rotator • choice of good working point All topics are being addressed in the TDR

15. Low emittance tuning • VERY important in SuperB, since design ey is 7 and 4 pm • Contributions to ey come mainly from: • tilts in quadrupoles • misaligned sextupoles • vertical dispersion • beam coupling • IBS • trickle injection • beam instabilities • Computer modeling as well as diagnostics will help in achieving and maintaining ey • This work has just started, luckily we can profit of work performed for, and experience at, ATF, SLS, CESR-TA and ILC-DR

16. Low emittance tuning Comparison of achieved beam emittances Comparison of rings with similar beam energy and ATF, SLS (* achieved)

17. Polarization IP • Polarization of one beam is included in SuperB • Either energy beam could be the polarized one • The LER would be less expensive, the HER easier • HER was chosen • Longitudinal polarization times and short beam lifetimes indicate a need to inject vertically polarized electrons. • The plan is to use a polarized e- source similar to the SLAC SLC source. • There are several possible IP spin rotators: • Solenoidslook better at present (vertical bends give unwanted vertical emittance growth) • Expected longitudinal polarization at IP ~ 87%(inj) x 97%(ring) =85%(effective) • Polarization section implementation in lattice is in progress Half IR with spin rotator (Wienands, Wittmer)

18. Lattice layout: PEP-II magnets reuse Total length 1800 m 20 m 280 m Dipoles Available Needed Quads Sexts All PEP-II magnets can be used, dimensions and fields are in range RF requirements are met by the present PEP-II RF system

19. IR layout, siam twins QD0 (R&D) M.Sullivan (SLAC) • QD0 is common to HER and LER, with axis displaced toward incoming beams to reduce synchrotron radiation fan on SVT • Dipolar component due to off-axis QD0 induces, as in all crossing angle geometries, an over-bending of low energy out coming particles eventually hitting the pipe or detector • New QD0 design based on SC “helical-type” windings S. Bettoni (CERN), E. Paoloni (Pisa) A pm QD0 design also in progress (SLAC)

20. SuperB footprint on Tor Vergata site SuperB rings

21. Synergy with the ILC (1) • ILC-DR and SuperB will face similar demands on beam quality and stability: SuperB for direct production of luminosity, and ILC-DR for reliable tuning and operation of the downstream systems, for luminosity production from the extracted beams • There are significant similarities between SuperB storage and ILC-DR parameters (see Table) • Beam energies and bunch lenghts are similar • ILC-DR have a circumference 3 times larger and smaller nominal bunch charge. Nevertheless, one may expect the beam dynamics to be in comparable regimes • Emittances are also similar (lower in ILC-DR), with similar problems for tuning

22. Comparison of parameters for SuperB and ILC-DR

23. Synergy with the ILC (2) • Significant issues common to both SuperB and ILC include: • Alignment of magnets, and orbit and coupling correction with the precision needed to produce vertical emittances of just a few pico-meters on a routine basis • Optimization of lattice design and tuning to ensure sufficient dynamic aperture for good injection efficiency (for both) and lifetime (particularly for SuperB LER), as well as control of emittances • Feedbacks (IP and rings) • Control of beam instabilities, including electron cloud, ion effects and CSR • Reduction of magnet vibration to a minimum, to ensure beam orbit stability at the level of a few microns

24. An example: proposed new 3 Km DR layout • Using the DCO lattice straights a shorter layout (half) has been designed • SuperB-like arc cells used (large x-phase advance/cell) instead of FODO • Lower emittance, same damping time, has been achieved • Emittance tunable with x-phase advance/cell#1 Momentum compaction also easily tunable from 1.4x10-4 to 2.7x10-4 LCWS08 Workshop, Fermilab, Dec. 2008

25. Synergy with the ILC (3) • All these issues are presently active areas of research and development for the ILC • Advantage could be taken whether the facilities are constructed and commissioned sequentially, or in parallel. • In general, the similarity of the proposed operating regimes for the ILC-DR and SuperB presents an opportunity for a well-coordinated program of activities that could yield much greater benefits than would be achieved by separate, independent research and development programs

26. Conclusions • A Conceptual Design Report has been published in May 2007 and positively reviewed by an International Review Committee,chaired by J. Dainton (UK) • A Machine Advisory Committee, chaired by J. Dorfan (SLAC), has scrutinized the machine design in July 2008 endorsing the design approach • The next step will be to complete the Technical Design Report by 2010 (SuperB Workshop in Paris, Feb. 15-18, will be the starting time) • Synergy with the ILC accelerator R&D are many. Collaboration started already on personal basis, it would be good to strenghten it with official commitments from both communities