1. SLAC Accelerator Department PEP-II Super-B-Factory Collider John T. Seeman Assistant Director of the Technical Division Head of the Accelerator Department DESY Meeting November 9, 2004

2. SLAC Accelerator Department Abstract: B Physics at a Super B Factory Part I: The Detector and Physics Capability [David MacFarlane] Part II: The Collider [John Seeman] Abstract: The present generation of B Factories at SLAC and KEK have now accumulated between them more than 0.5 ab -1 of e+e- to Upsilon(4S) events or about 500 million B-anti-B meson pairs. These samples have been used to establish CP violation in the B meson system and to study rare B decays with unprecedented sensitivity, both within the context of the Standard Model and as a window for new physics. There may even be hints for new physics in b to s penguin modes in present data, which is, in any event, an important example for the future. Building on the successful foundation of KEKB and PEP-II, including an understanding of the capabilities for both the colliders and detectors, the B Factory community is now looking at the physics case and technical requirements for extrapolating present day luminosities another factor of 20-50 at so-called Super B Factories. These talks will examine the physics case for the Super B Factory, the technical requirements and parameters for the collider, and the implications for an upgraded detector that have emerged at SLAC and KEK.

3. SLAC Accelerator Department Topics Brief status: PEP-II and short range plans Super-B-Factory Collider parameters Super-B-Factory Plans

4. SLAC Accelerator Department SLAC Beam Lines

5. SLAC Accelerator Department PEP-II e + e - Collider Use the SLAC linac as upgraded for the SLC for the injector. BaBar Detector Feedbacks Diagnostics LER RF 476 MHz HER RF 476 MHz 3.1 GeV positrons x 9 GeV electrons C = 2200 m

6. SLAC Accelerator Department PEP-II arc section

7. SLAC Accelerator Department PEP-II Interaction Region Components near BaBar HER LER Collision point BaBar

8. SLAC Accelerator Department

9. Improvements last year –Peak luminosity (L): 6.6  9.2  10 33 –Number of bunches: 1050  1588 bunches by-2 pattern (24 long mini-trains) with 2% ion gap –Parasitic collision effects seen but small(<5% on L) –Electron Cloud (ECI) effects are small (<2% on L) –I  current 1500  2450 mA (3 RF stations) –I  current 1050  1550 mA (8 RF stations)  y * of 12  11 mm –All data now taken in trickle charge mode Both beams: LER in November, HER in March

10. SLAC Accelerator Department Peak luminosity of 9.21 x 10 33 PEP-II Record Peak Luminosity

11. SLAC Accelerator Department Daily Integration Record with Trickle Injection 710/pb LER I HER I Luminosity

12. SLAC Accelerator Department Trickle injection at the B Factories Best shift, no trickle PEP-II: ~5 Hz continuous KEKB: at ~5-10 min intervals Best shift, LER only trickle Nov 2003 Best shift, double trickle Mar 2004 PEP-II Lumi HER current LER current

13. SLAC Accelerator Department PEP-II Performance Measure: Peak Luminosity

14. SLAC Accelerator Department

15. Total >240 fb -1 !

16. SLAC Accelerator Department Overall Parameters and Goals ParameterUnitsDesign Best in collision Future 2007 goal I+mA214024504500 I-mA75015502200 Number bunches 165815881715 y*y* cm15-20118 yy 0.030.045, 0.070.055-0.08 Luminosityx10 33 3.09.224 Integrated lumi / day pb -1 1307101800 Over five times design! Over three times design Twice design

17. SLAC Accelerator Department New transverse kicker electrodes

18. SLAC Accelerator Department New Longitudinal Feedback Kicker Assembly

19. SLAC Accelerator Department New LER Synchrotron Light Monitor Improved resolution Single bunch capabilities

20. SLAC Accelerator Department Near Term PEP-II Goals 530 fb -1 total integrated by Fall 2006. About 1.5 to 1.8 ab -1 integrated by Fall 2010.

21. SLAC Accelerator Department PEP-II/BaBar Roadmap: Super B-Factory Study The Roadmap Committee is studying the long range future of PEP-II and BaBar with a possible large upgrade at the end of the decade. A Super-PEP-II could produce 10 ab -1 per year with a peak luminosity of 7 x 10 35 /cm 2 /s. Accelerator parameter goals have been set and work towards a solid design has started. The long range time goal is to have a new upgraded accelerator running in 2011 or 2012.

22. SLAC Accelerator Department Achieving Super B Luminosities Higher Currents: oMore rf power, cooling, injector oMore HOM heating (more bunches) oBeam instabilities oElectron clouds, fast ions Smaller  y *: oSmaller physical/dynamic aperture oShorter lifetime, more background Shorter  z : oMore HOM heating oCoherent synchrotron radiation oShorter lifetime, more background Higher tune shifts: oHead-on collisions replaced by angled crossing oDegrades maximum tune shift unless crabbing cavities used

23. SLAC Accelerator Department Parameters for High-Luminosity B Factory Luminosity (x10 34 ) 0.92.4152570Units e+e+ 3.1 3.58.0GeV e-e- 9.0 8.03.5GeV I+I+ 2.454.58.711.06.8A I-I- 1.552.23.04.815.5A  (y*) 1183.63.01.5mm  (x*) 30 2515cm Bunch length107.543.41.7mm # bunches15881700 34506900 Crossing angle000  11  15 mrad Tune shifts (x/y) 4.5/78/811/11 x100 rf frequency476 952MHz Site power40 7585100MW J.Seeman Jul 04Jul 07 LER vacuum +IR+HER vacuum, 952MHz rf

24. SLAC Accelerator Department Lessons learned from PEP-II & KEKB Asymmetric beam energies work well. Energy transparency conditions are relatively weak. Asymmetric interaction regions can be operated. IR backgrounds can be handled though are not easy. High current RF can be operated (1 A x 2 A). Bunch-by-bunch feedbacks work (4 ns spacing). Beam-beam tune shifts reach 0.08 (v) to 0.10 (h). Injection rates good; continuous injection feasible. Electron Cloud Instability (ECI) ameliorated for now!

25. SLAC Accelerator Department New techniques for Super B-Factory Beam lifetimes will be low  continuous injection. Very low  y * (6 to 10 mm  1.5 to 3 mm). Higher beam-beam parameters (trade beam-beam lifetimes for tune shifts) Higher beam currents (x 5 or so). Higher frequency RF (more bunches). Bunch-by-bunch feedbacks at the 1 ns scale. Very short bunch lengths (<2 mm). High power vacuum chambers with antechambers and improved or no bellows. Reduce energy asymmetry to save wall power.

26. SLAC Accelerator Department LER aluminum vacuum system: limit at 4.5A Total LER SR power = 2 MW High power photon stops Antechambers Reduce Electron- Cloud-Instability 4.5 A at 3.1 GeV Photon Stop limits

27. SLAC Accelerator Department Vacuum system for Super B Factory (S-KEKB) Antechamber and solenoid coils in both rings. Absorb intense synchrotron radiation. Reduce effects of electron clouds. Circular-chamber Ante-chamber with solenoid field Build-up of electron clouds

28. SLAC Accelerator Department Electron Cloud Instability & multipacting

29. SLAC Accelerator Department Windings added for ECI reduction

30. SLAC Accelerator Department PEP-II HER RF cavities

31. SLAC Accelerator Department HOM calculations: 476 MHz cavity 476 MHz cavity with a larger beam opening S.Novokhotski R beam = 95.25 mm Total loss = 0.538 V/pC Loss integral above cutoff = 0.397 V/pC HOM Power = 203 kW @ 15.5A

32. SLAC Accelerator Department HOM calculations: 952 MHz cavity 952 MHz cavity with a larger beam opening S.Novokhotski R beam = 47.6 mm Total loss = 0.748 V/pC Loss integral above cutoff = 0.472 V/pC HOM Power = 121 kW @ 15.5A

33. SLAC Accelerator Department IR concept for a Super B-Factory M.Sullivan ±12 mr crossing angle oNo background calculations yet Can luminosity component be reduced?

34. SLAC Accelerator Department New IR magnet design (Parker)

35. SLAC Accelerator Department New IR magnet design Quadrupole, anti- solenoid, skew quadrupole, dipole and trims located in one magnet. All coils numerically wound on a bobbin.

36. SLAC Accelerator Department Luminosity-dependent backgrounds oSR in bend & quadrupole magnets oCurrent dependent terms due to residual vacuum oBhabha scattering at IP PEP-II Head-On IR Layout

37. SLAC Accelerator Department Activities towards luminosity upgrade crossing angle 22 mrad Head-on(crab) ◊ ◊ ◊ ◊ ◊ yy (Strong-weak simulation) (Strong-strong simulation) Crab crossing may boost the beam-beam parameter up to 0.2! Superconducting crab cavities are under development, will be installed in KEKB in 2006. K. Ohmi K. Hosoyama, et al

38. SLAC Accelerator Department Power scaling equations Synch rad ~ I E 4 /  Resistive wall ~ I 2 total /r 1 /f rf /  z 3/2 Cavity HOM ~ I 2 total /f rf /  z 1/2 Cavity wall power = 50 kW Klystron gives 0.5 MW to each cavity Magnet power ~ gap ~ r 1

39. SLAC Accelerator Department Site power limits 476 MHz 952 MHz (Linac, PEP-II magnets and campus power = 40 MW) 1.5x10 34 2.5x10 34 7x10 34

40. SLAC Accelerator Department Recommended scenario: 7 x 10 35 Replace present RF with 952 MHz frequency over period of time. Use 8 x 3.5 GeV with up to 15.5 A x 6.8 A. New LER and HER vacuum chambers with antechambers for higher power (x 4). Replace LER magnets to soften radiation and resistive wall losses; rework HER magnets as well. New bunch-by-bunch feedback for 6900 bunches (every bucket) at 1 nsec spacing. (Presently designing feedback system being 0.6-0.8 nsec spacing.) Push  y * to 1.5 mm: need new IR (SC quadrupoles) with 15 mrad crossing angle and crab cavities

41. SLAC Accelerator Department Possible Timeline for Super B Program LOI Construction of upgrades to L = 5-7x10 35 Super-B Program CDR Installation R&D, Design, Proposals and Approvals P5 Construction 2001 20032010200820062005 Planned PEP-II Program (June 30, 2003)(End 2006) (PEP-II ultimate) Commission 2012 Super B Operation 2011

42. SLAC Accelerator Department Conclusions PEP-II has reached a luminosity of 9.2  10 33 /cm 2 /s in May 2004. PEP-II has delivered 710 pb -1 in one day and over 256 fb -1 since May 1999. Trickle injection is used in both rings all of the time. Planned upgrades toward 2.4  10 34 are on track. We will finalize technical specifications over the next few months for the 2005 and 2006 downs. The parameters of a Super-B-Factory were studied with RF frequencies of 476 MHz and 952 MHz. At the present, for 90 to 120 MW of total power, linac and campus included, 476 MHz provides a luminosity of about 2 to 4 x 10 35 and 952 MHz provides about 0.7 to 1.0 x 10 36. Vertical beam-beam parameters are 0.107. Studies are continuing with a technical document coming about January.

43. SLAC Accelerator Department PEP-II upgrades schemes Luminosity (x 10 35 ) 1.52.57 5757 RF frequency (MHz) 476 952 476  95 2 Site power (MW) 7585100 70  100 Crossing angleNoYes Crab cavitiesNoYes Replace LERYes Replace HERNoYes UpgradeableNo Yes (to 952MHz) Yes Detector requirements depend on projecting backgrounds for luminosities that are >20 times larger than at present Recommended

44. SLAC Accelerator Department

46. Important Factors in Upgrade Direction Project is “tunable” –Can react to physics developments –Can react to changing geopolitical situation Project anti-commutes with linear collider Will emerge from BABAR and Belle, but could be attractive to wider community in context of other opportunities –As we learn more about machine and detector requirements and design, can fine tune goals and plans within this framework Project has headroom –Major upgrades to detector and machine, but none contingent upon completing fundamental R&D –Headroom for detector up to 5 x 10 35 ; with thin pixels beyond –Headroom for machine up to 8.5 x 10 35 ; requires additional rf, which can be staged into machine over time

47. SLAC Accelerator Department Timeline for a Super-B-Factory at PEP-II The key is the approval date by DOE’s P5 and to enter the DOE Budget cycle for FY2008 which is about July of 2006! Thus, the plan as needed: SBF LOI to the SLAC EPAC/SPC in late 2004. SBF LOI to the NAS in January 2004. SBF CDR to SLAC EPAC/SPC in Fall 2005. CDR endorsed by SLAC EPAC/SPC in January 2006. CDR endorsed by NAS in Spring 2006. P5 approves SBF proposal in June 2006. DOE enters SBF into FY2008 Budget in Fall 2006. SBF receives construction funds about January 2008. Construct SBF parts for 1.5 years while running present PEP-II. Run PEP-II to July of FY2009. Install for two years. Start SBF data taking in July 2011with 3x10 35 collider. Upgrade to 7 x 10 35 in two years (by fall 2013).

48. SLAC Accelerator Department Super KEKB machine parameters Beam-beam parameter is obtained from simulations: strong-strong (weak-strong)

49. SLAC Accelerator Department Coherent synchrotron radiation Numerical simulations with mesh (T.Agoh and K.Yokoya) –Analytic formula is not reliable due to strong shielding. Loss factor estimation : –No synchrotron oscillation and no interference between bends. –1 V/pC for 6 mm bunch length (LER) –10 V/pC for 3 mm bunch length (LER) ⇔ 30~40 V/pC in the ring Energy change as a function of z/  z KEKB LER/ 2.6A (5120) bunch length dependence chamber height dependence