1. PEP- II Linac Accelerator Systems Department The PEP-II B-Factory Accelerator John T. Seeman Assistant Director Particle and Particle-Astrophysics Division SLAC DOE HEP Review June 14, 2005

2. PEP- II Linac Accelerator Systems Department Topics Highlights of Run 5 of PEP-II Run plan through 2008 How to increase the luminosity to 2.1 x 10 34 Future down work

3. PEP- II Linac Accelerator Systems Department The PEP-II Team August 2004

4. PEP- II Linac Accelerator Systems Department Beam Lines

5. PEP- II Linac Accelerator Systems Department PEP-II arc section

6. PEP- II Linac Accelerator Systems Department PEP-II HER RF cavities

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

8. PEP- II Linac Accelerator Systems Department PEP-II Machine Advisory Committee Reviews PEP-II Machine Advisory Committee –1) Jan 4-6, 1995 –2) August 24-25, 1995 –3) April 11-13, 1996 –4) January 6-8, 1997 –5) November 10-13, 1997 –6) December 14-16, 1998 –7) October 9-11, 2003 –8) April 15-17, 2004 –9) December 13-15, 2004 –10) October 5-7, 2005

9. PEP- II Linac Accelerator Systems Department Other Program Reviews DOE Operations Review in June 2004 PEP-II End of Run Review August 2004 PEP-II Restart Validation Review February- March 2005 SPC May 2005 DOE Operations Review in late Summer- early Fall 2005

10. PEP- II Linac Accelerator Systems Department PEP-II Safety Planning and Restart Plan Electrical accident at SLAC on October 11, 2004. All running of accelerators stopped. Safety training with new procedures October 2004 – March 2005. Type A Investigation October-December, 2004. Corrective Action team: December 2004-January 2005. Restart Validation Review: February 2005. “Pre-restart” conditions completed March 2005. Linac and PEP-II operations start up April 15, 2005. Power outage: May 18-20. Beams returned about May 25. FFTB beam line revalidated June 2, 2005. FFTB beam started June 3, 2005.

11. PEP- II Linac Accelerator Systems Department 230 kV Lines

12. PEP- II Linac Accelerator Systems Department The cable break area 230 kV lines

13. PEP- II Linac Accelerator Systems Department The tree that fell (100 ft tall) Neighbor’s tree Stanford tree

14. PEP- II Linac Accelerator Systems Department Power line loose cables

15. PEP- II Linac Accelerator Systems Department

16. PEP- II Linac Accelerator Systems Department String new wires by crane

17. PEP- II Linac Accelerator Systems Department Summer 2004 PEP-II Improvements IR2 south forward shield wall: Backgrounds Add another new LER RF station: Higher current Add a HER RF station by splitting up a current 4 cavity station into two 2 cavity stations: Higher current Two new “Frascati” longitudinal kickers in LER: More stability New electrodes for transverse kickers: More stability Add fans to all HER bellows: Cool Higher Order Modes (HOMs) Alignment work (quadrupole rolls): Smaller vertical emittance New LER synchrotron light monitor: Smaller vertical emittance IR NEG pump HOM reduction: Better lifetime and backgrounds New Support Tube Chiller: Higher currents

18. PEP- II Linac Accelerator Systems Department PEP-II Run Schedule PEP-II Run 5 started April 15, 2005. Will collide steadily from April 2005 through July 2006 with a one month break in October 2005. Next ROD (repair day) about August 3, 2005. Down in 2006 August through November for BaBar, PEP-II, and LCLS upgrade work. Three month down in Summer-Fall 2007 for LCLS work. Collide through September 2008.

19. PEP- II Linac Accelerator Systems Department October Down Tasks Safety –PPS recertification –PEP-II NIT lighting –Linac switch gear work –New K1A/B and K10B substations Routine maintenance PEP-II Upgrades –New x-y BPMs –RF work –IR vacuum chambers LCLS installation –Beam pipe through Sector 20 wall –Beam stoppers –Waveguide work –Accelerating section work –Sector 24 stairs installation

20. PEP- II Linac Accelerator Systems Department Daily Integration Record with Trickle Injection 710/pb LER I HER I Luminosity

21. PEP- II Linac Accelerator Systems Department PEP-II Monthly Peak Luminosity

22. PEP- II Linac Accelerator Systems Department

23. PEP- II Linac Accelerator Systems Department

24. PEP- II Linac Accelerator Systems Department Prediction July 2003 Actual

25. PEP- II Linac Accelerator Systems Department Prediction April 2005 Actual Power outage

26. PEP- II Linac Accelerator Systems Department PEP-II Issues Recent issues: –Positron source coil short –Positron source vacuum leak –PEP-II HER arc vacuum chamber water plugs –PEP-II LER trouble with orbit steering –PEP-II klystron failure (collector damage) –Power outage changed conditions Present issues: –Changing machine conditions over hours (orbits?) –Luminosity droop along mini-trains: (wakefields, parasitic collisions, electron cloud, RF loading?)

27. PEP- II Linac Accelerator Systems Department Change of specific luminosity over mini-trains Mini-trains Specific luminosity Luminosity

28. PEP- II Linac Accelerator Systems Department Luminosity Equation  y is the beam-beam parameter (~0.065)  I b is the bunch current (1 to 3 mA)  n is the number of bunches (~1600)  y * is the IP lattice optics function (vertical beta) (10 mm)  E is the beam energy (3.1 and 9 GeV)  Luminosity (10 33 cm -2 s -1 )

29. PEP- II Linac Accelerator Systems Department Future luminosity increase factors ParameterPresentFutureLuminosity gain ratio Hardware and work needed LER current2450 mA4500 mATwo RF stations, new IR vacuum chambers HER current1550 mA2200 mA 1.61Two RF stations, new IR vacuum chambers y*y* 10.5 mm8.5 mm 1.24HER higher tunes, RF & power supplies work yy 0.065 L 0.043 H 0.070 L 0.055 H 1.17Tune plane, coupling, & IR work Total x 2.3

30. PEP- II Linac Accelerator Systems Department Overall Parameters and Goals ParameterUnitsDesign Best in collision Future 2007 goal I+mA214024504500 I-mA75015502200 Number bunches 165815881715 y*y* mm15-20118.5 Bunch length mm1511-129 yy 0.030.043-0.0650.055-0.07 Luminosityx10 33 3.09.221 Int lumi / day pb -1 1307101300 Over five times design!Over three times design Twice design

31. PEP- II Linac Accelerator Systems Department PEP-II Future Luminosity Parameters xx yy xx yy nI x*x* y*y* Lumi xx yy Unitscmmmnm mA mm mm x1E33 LER now 3210.5331.55161624501034.09.210.0530.065 LER 2007 288.5471.80172045001153.921.00.0650.070 HER now 3310.5601.30161615501393.79.210.0520.043 HER 2007 288.5661.60172022001363.721.00.0630.055

32. PEP- II Linac Accelerator Systems Department Future PEP-II Improvement Activities New transverse digital feedback processors (Summer 2005) New RF comb filters (Fall 2005) New klystron linearizer (Spring 2006) Install LER-5 RF station (Fall 2006) Install HER-10 RF station (Fall 2006) Upgrade several high-power IR vacuum chambers (Q2, Q4, Q5, Q2 bellows, LER abort spoiler, straight section bellows …) (Fall 2006) HER lattice upgrade for lower momentum compaction and shorter bunches (Fall 2006)

33. PEP- II Linac Accelerator Systems Department

34. Local Chamber Area Dots show new chamber locations.

35. PEP- II Linac Accelerator Systems Department New IP Be bellows design SiC Cooling

36. PEP- II Linac Accelerator Systems Department New Q2 Chamber Forward

37. PEP- II Linac Accelerator Systems Department Forward Q2 Chamber (HER/LER) LER leg HER leg

38. PEP- II Linac Accelerator Systems Department Straight HOM Bellows -Design Details GlidCop Stub Inconel Spring Finger GlidCop RF Shield Finger Welded Bellows Absorbing Tile 2.75” long by.24” wide HOM Trapping Slots Modes in the chamber propagate through the slots & are absorbed by the AlNiSiC. Bellows Cavity Modes that leak past the RF shield finger and are trapped in this area still see the absorber Beam Direction

39. PEP- II Linac Accelerator Systems Department New Q5 HER Chamber

40. PEP- II Linac Accelerator Systems Department Q5 HER details

41. PEP- II Linac Accelerator Systems Department HER Q4 Chambers Q5R BPM Q4R BPM 27.5 inches 14 inches e- Looking upbeam BPM Timing BPMs Electron BPMs

42. PEP- II Linac Accelerator Systems Department Q4/Q5 Bellows Layout Q4 side, 10” flange Q5 side 12” flange GlidCop Stub Inconel Spring Finger GlidCop RF Shield Finger Welded Bellows Cooling – not shown Absorbing Tile

43. PEP- II Linac Accelerator Systems Department IR Q4-Q5 bellows with HOM Absorbers

44. PEP- II Linac Accelerator Systems Department Accelerator Physics Studies Needed for 2x10 34 Better understanding of beam-beam effects –Parasitic crossings –Small crossing angles –Higher tune shifts Reduce beam aborts –RF trips –Longitudinal instabilities –Transverse instabilities –Better backgrounds Better magnetic lattice optics –Lower  y* –Reduce  beats –Improve luminosity tuning knobs Increase LER emittance with wigglers Continue to improve HOM damping at higher currents Determine instability growth rates in LER/HER at high currents –Transverse –Longitudinal –Electron cloud Machine-detector interface –Reduce backgrounds in trickle charge –Reduce IP pressure with current

45. PEP- II Linac Accelerator Systems Department Expected PEP-II Delivered Integrated Luminosity End of fiscal year Total PEP-II Projection Delivered “Yearly change” Peak Luminosity x 10 33 FY2004256/fb117/fb9.2 FY20053388210.5 FY200651617813 FY200772220620 FY2008109737521 Projection May 2005

46. PEP- II Linac Accelerator Systems Department Integrated Luminosity Goals Now

47. PEP- II Linac Accelerator Systems Department Conclusions Restart Validation Process for PEP-II has been completed. Run 5 plan has started. PEP-II turn on in Run 5 is going well (in spite of the power outage). PEP-II has delivered over 14 fb -1 in Run 5 and over 270 fb -1 since May 1999. Trickle injection in both rings all of the time. Planned upgrades towards 2.1  10 34 are on track. Goal is more than 1 ab -1 in 2008. Run and down schedules have been mapped until 2008.