SuperB Accelerator & ILC SuperB Accelerator & ILC M. E. Biagini, LNF-INFN for the SuperB Team ILC GDE visit, LNF, Jan. 22 th 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 is an international enterprise aiming at the construction of a very high luminosity (10 36 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: [hep-ex]) SuperB: a cm -2 s -1 accelerator

3 B-Factories (PEP-II and KEKB) have reached high luminosity (>10 34 cm -2 s -1 ) but, to increase L of ~ 2 orders of magnitude, bordeline parameters are needed such as:  Very high currents HOM in beam pipe overheating, instabilities, power costs detector backgrounds increase  Very short bunches RF voltage increases costs, instabilities  Smaller damping times Wiggler magnets costs, instabilities  Crab cavities for head-on collision KEKB experience Accelerator basic concepts (1) Difficult and costly operation

4 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 (  = tg(  z /  x ) interaction region geometry  Currents comparable to present Factories lower backgrounds, less HOM and instabilities Basic concepts (2) Requires a lot of fine machine tuning Small collision area:  x /  Accelerator basic concepts (2)

5 Ultra-low emittance Very small    at IP Large crossing angle “Crab Waist” transformation Small collision area Lower    is  possible NO parasitic crossings NO x-y-betatron resonances 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 DA  NE A new idea for collisions 1. P.Raimondi, 2° SuperB Workshop, March P.Raimondi, D.Shatilov, M.Zobov, physics/

6 Relatively easier to make small  x with respect to short  z Problem of parasitic collisions automatically 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 consumptionand...

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

8 Typical case (KEKB, DA  NE): 1. low Piwinski angle  < 1 2.  y comparable with  z Crab Waist On: 1. large Piwinski angle  >> 1 2.  y comparable with  x /  Much higher luminosity! D.Shatilov’s (BINP), ICFA08 Workshop Example of x-y resonance suppression

9 Comparison of SuperB to Super-KEKB ParameterUnitsSuperBSuper-KEKB EnergyGeV4x73.5x8 Luminosity / cm 2 /s 1.0 to to 0.8 Beam currents A1.9x1.99.4x4.1 y*y* mm x*x* cm3.5x Crossing angle (full) mrad to 0. RF power (AC line) MW20 to 2580 to 90 Tune shifts(x/y)0.0004/ /0.3 IP beam distributions for KEKB IP beam distributions for SuperB

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 DA  NE 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  *  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 1x10 36 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  HER  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  y is 7 and 4 pm Contributions to  y 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  y 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 E (GeV)C (m)Gamma  x (nm)  x (  m)  y (pm)  y (nm) Spring ILC-DR Diamond* ATF* SLS* SuperB LER SuperB HER Comparison of rings with similar beam energy and ATF, SLS (* achieved)

17Polarization 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:  Solenoids look 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 IP Half IR with spin rotator (Wienands, Wittmer)

18 Total length 1800 m 280 m 20 m L mag (m) PEP HER-194 PEP LER194- SBF HER-130 SBF LER22418 SBF Total Needed300 Dipoles L mag (m) PEP HER PEP LER SBF HER SBF LER SBF Total Needed51* Quads Available Needed All PEP-II magnets can be used, dimensions and fields are in range RF requirements are met by the present PEP-II RF system L mag (m) PEP HER/LER188- SBF Total3724 Needed1844 Sexts Lattice layout: PEP-II magnets reuse

19 IR layout, siam twins QD0 (R&D) 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 M.Sullivan (SLAC) 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 SuperB LERSuperB HERILC-DR Beam energy4 GeV7 GeV5 GeV Circumference1800 m 6695 m Particles per bunch 5.5   Number of bunches Average current1.85 A 0.40 A Horizontal emittance2.7 nm1.6 nm0.8 nm Vertical emittance7 pm4 pm2 pm Bunch length5 mm 6 mm Energy spread0.08%0.058%0.13% Momentum compaction factor 3.2    Transverse damping time40 ms 25 ms RF voltage5 MV8 MV24 MV RF frequency476 MHz 650 MHz

23 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 Synergy with the ILC (2)

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 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 Synergy with the ILC (3)

26 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 , 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 communitiesConclusions