1. Accelerator R&D Results from the B-factory
M. Sullivan
PEP-II run coordinator 1

2. Outline PEP-II Parameters High-current running IR design Summary
Vacuum designs
RF systems
Bunch by bunch feedbacks
High-current running
Synchrotron radiation power
HOM power
IR design
SuperB IR design
Summary 2

3. PEP-II Rings
BaBar Detector 3

4. PEP-II tunnel 4

5. PEP-II parameters Circumference (m) 2200 RF frequency (MHz) 456
Number of RF buckets
Number of bunches
Bunch spacing (m)
LER HER
Beam current (A) 2.9 (2.99) 1.85 (1.9)
Particles per bunch 8 1010
Beam energy (GeV)
Collision beam sizes (m) 100x5
Collision Head-on
Luminosity (cm-2 sec-1) 1034
Highest beam currents and more positrons than anyone else 5

6. Vacuum Systems HER LER Base pressures are less than a nTorr
Long (5.4 m) PEP-I dipoles led to distributed ion pumps (DIPS)
Copper system
LER
Short (0.45 m) dipoles to decrease the damping time led to ante-chambers with photon stops and massive titanium sublimation pumps (TSPs)
Aluminum system (TiN)
Base pressures are less than a nTorr
Dynamic pressures are a few nTorr
More Amp-hours than any other accelerator
Over 50,000 Amp-hrs for the LER
Over 30,000 Amp-hrs for the HER 6

7. RF System and Feedbacks
RF systems
Minimal stored energy
Power efficient
Beam loading is high
State of the art low-level feedback system to control klystron power and phase
Fast feedback systems to control multi-bunch instabilities in the transverse and longitudinal dimensions
Longitudinal system has been installed in several other storage rings 7

8. High Beam Currents Synchrotron Radiation power HOM power Ion gap
6.4 MW for the HER at 1.8 A
2.3 MW for the LER at 3 A
HOM power
Absorbing elements
Pump screens
Bellows screens
Ion gap
Gap is now 1% -- ions have only seen when the vacuum is high
Electron cloud
Successfully controlled by solenoid windings 8

9. HOM power damage
RF seal between two flanges in the HER 9

10. Absorber designs
S. Weathersby
A. Novokhatski 10

11. Design for a HOM Absorber Module11

12. Bellows Design with Exposed Tiles12

13. New Absorber Design
Absorber tiles are now behind the bellows fingers and the spacing between the fingers is quite large to allow high frequency RF to pass through 13

14. IR Design
Uses permanent magnets for accelerator components inside the detector magnetic field
Require no power
Are always on – reduces the probability that an uncontrolled beam will crash into the detector
Maintenance free
Self-shielding 14

15. PEP-II Interaction Region
BaBar Detector 15

16. IR Layout 16

17. Super B Factory
Worked on an interaction region design for a Super B Factory
The design incorporates super-conducting elements as well as permanent magnet elements for the final focus optics
Similar beam currents and storage ring sizes as PEP-II
Ring optics, HOM issues, beam stability…
Trickle injection – pioneered at PEP-II and KEKB is a crucial ingredient for any future high-current collider
About one FTE at SLAC works on the SuperB to support the world wide effort . Not directed to any one particular site yet… 17

18. Super B Interaction Region18

19. SuperB IR Closeup 19

20. Summary PEP-II is a working accelerator with high-current rings
Many of the issues for the ILC damping rings have been or can be studied at PEP-II
Over 100 accelerator papers have been written about PEP-II with regard to the high-current performance
As we increase beam currents, PEP-II will move further into the frontier of high-current storage rings 20