SLAC Accelerator Department PEP-II Future Plans and Parameters John T. Seeman PEP-II MAC Meeting December 13, 2004

SLAC Accelerator Department Contributors to PEP-II SLAC LBNL LLNL With help from: –IHEP, Beijing, China –BINP, Novosibirsk, Russia –INFN, Frascati, Italy –KEK, Tsukuba, Japan –CEA, Saclay, France –IN2P3, Paris, France –Caltech –BNL –Many people from the BaBar Collaboration –Visitors from CERN, DESY, Cornell, FNAL, …

SLAC Accelerator Department The PEP-II Team August 2004

SLAC Accelerator Department Beam Lines

SLAC Accelerator Department PEP-II arc section

SLAC Accelerator Department PEP-II HER RF cavities

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

SLAC Accelerator Department Other reviews since the last PEP-II MAC DOE Operations Review in June 2004 (Next DOE Operations Review May 2005) PEP-II End of Run Review August 2004

SLAC Accelerator Department Operational Improvements in FY2004 –Peak luminosity: 6.6  9.2  –Number of bunches: 1050  1588 bunches by-2 pattern (24 long mini-trains) with 2% ion gap –Parasitic collision effects seen but small(<5%) –Electron Cloud (ECI) effects are small (<2%) –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

SLAC Accelerator Department PEP-II Performance Measure: Peak Luminosity

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

SLAC Accelerator Department Run 1 Run 2 Run 3 Run 4 CD4 Design Performance

SLAC Accelerator Department

SLAC Accelerator Department

Luminosity versus Crossing Angle Without parasitic crossing With parasitic crossing Kozanecki Sullivan Cai

SLAC Accelerator Department Beam-Beam Observed and Simulated Kozanecki Sullivan Cai Narsky Dynamic beta effects Beam-beam limit effects

SLAC Accelerator Department Response to April 2004 PEP-II MAC Questions Aborts per day: Down to 5 to 6 per day in July (McIntosh) IR upgrade reduced  y *: Designing for 7 mm, hope to get 8.5 mm (Sullivan, Biagini) IR vacuum work: Ongoing (Kurita, Langton, Pope, Sheng, Kharakh, Metcalfe, DeBarger, Sullivan) IR vacuum model: Some progress (Sullivan, Student, Gierman) Q1/Q2 bellows design: Nearly designed (Kurita, Langton, Novokhatski) Radial ion pump: Designed (Kurita, Wright) B1 magnet upgrade: Some studies done. No decision yet. Likely we will make no changes. (Ecklund, Sullivan) LER arc HOM TSP heating: Sources now known (collimators). Extra absorber to be installed (Novokhatski, Kulikov, Langton) “IR outgassing storms”: NEGs are heated by e+ beam (Sullivan, Ecklund, Metcalfe) RF engineering positions: Hired two new people. Tried to hire a third person. He turned us down. Now most hires are frozen due to 2005 budget.

SLAC Accelerator 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

SLAC Accelerator Department New IR2 Shield Wall for BaBar IFR

SLAC Accelerator Department Windings finished for ECI reduction

SLAC Accelerator Department LER NEG Test chamber

SLAC Accelerator Department Existing 3082 chamber BPM Chamber support Cooling bar NEG plenum NEG heater Quad extrusion

SLAC Accelerator Department Chamber shown inverted and plenum not shown for clarity SiC HOM absorber

SLAC Accelerator Department New Longitudinal Feedback Kicker Assembly

SLAC Accelerator Department New transverse kicker electrodes

SLAC Accelerator 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 )

SLAC Accelerator Department Overall Parameters and Goals ParameterUnitsDesign Best in collision Future 2007 goal I+mA I-mA Number bunches y*y* mm yy , Bunch length mm Luminosityx Integrated lumi / day pb Over five times design! Over three times design Twice design

SLAC Accelerator 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 0.06 L H L H 1.17Tune plane, coupling, & IR work, vertical emittance Parasitic  x 3.22 mm3.80 mm 1.08B1 magnet change (?) Total x 2.52

SLAC Accelerator 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 LER HER now HER

SLAC Accelerator Department HER Single-Bunch Synchroscan Data at 16 MV Holtzapple Fisher Novokhatski

SLAC Accelerator Department Comparing Single-Shot and Synchroscan Data LER e+

SLAC Accelerator Department How to shorten the HER-LER bunch lengths Summer 2004  2007: –LER current: 2450 mA  4500 mA –HER current: 1550 mA  2200 mA –LER RF: 3 stations  5 stations –LER RF: 6  10 cavities –HER RF: 8 stations  10 stations –LER total RF voltage: 3.8 MV  7.7 MV –HER total RF voltage: 15.8  18.7 MV –HER Je 2.0  2.2 –HER Momentum compaction:  LER bunch length: 11.8 mm  8.7 mm HER bunch length: 11.4 mm  8.4 mm

SLAC Accelerator Department PEP-II Future Downs Nominal plan: –Down July-December 2005 BaBar IFR, PEP-II support tube, many PEP-II vacuum chambers –Down Aug-Sept 2006 Last RF station LER-5 + last upgraded chambers –Down Aug-Sept 2007 maintenance and PPS –Down Aug-Sept 2008 maintenance and PPS –Down Aug-Sept 2009 maintenance and PPS Option 1: –Run through except for three week down for PPS certification (When: December 2005?) (+maybe PEP-II HER-10 RF Station) –Down August-December 2006 BaBar IFR and PEP-II support tube –Downs in same as above Option 2: –Run through except for three week down for PPS certification (When: December 2005?) (+maybe PEP-II HER-10 RF Station) –Down May-September 2006 BaBar IFR and PEP-II support tube –Downs in same as above

SLAC Accelerator Department VTX Bellows Cooling Installation: Key issue in the future!

SLAC Accelerator Department New Be bellows design SiC Cooling Langton

SLAC Accelerator Department Expected PEP-II Delivered Integrated Luminosity Delivered as of end of fiscal yearPEP-II Projection“Delta” FY /fb117/fb FY FY FY FY FY FY Five month down

SLAC Accelerator Department Future Maintenance Down Activities Install LER-5 RF station Install HER-10 RF station Remove support tube for SVT work to fix radial ion pump, add an IR BPM, new Be bellows Upgrade several high-power IR vacuum chambers (Q4, Q5, high power dump, Q2 bellows, LER abort window, straight section bellows …) HER lattice upgrade for lower momentum compaction and shorter bunches New RF comb filters New klystron linearizer New transverse digital feedback processors

SLAC Accelerator Department Detailed PEP-II upgrade list IR2 new Q2 chamberApr-05 Transverse digital feedbackApr-05 RF woofer linkMay-05 IR2 Q2 bellowsJul-05 ST Be bellowsJul-05 ST radial ion pumpJul-05 ST new BPMJul-05 IR2 HER Q4LJul-05 IR2 HER Q4RJul-05 IR2 HER Q5LJul-05 IR2 HER Q5RJul-05 IR2 HER Q4-5 bellowsJul-05 IR2 LER Q4-5LJul-05 IR2 LER Q4-5RJul-05 LER Abort spoilerJul-05 LER new high power bellowsJul-05 PEP-II tunnel network upgradeJul-05 RF station HER 10Aug-05 HER tune power supply upgradeAug-05 RF comb-2 projectDec-05 RF klystron linearizerJan-06 RF station LER 5May-06 IR HER HOM absorbersMay-06 IR LER HOM absorbersMay-06 IR HER new high power dumpMay-06 IR New HER frangible linksMay-06 IR new LER frangible linksMay-06 IR new HER 12 m transition May-06 IR new NEG chamber upgradesMay-06 New longitudinal feedback systemMay-06 ProjectTime early to install

SLAC Accelerator Department Conclusions PEP-II has reached a luminosity of 9.2  /cm 2 /s. PEP-II has delivered 710 pb -1 in one day. PEP-II has delivered 117 fb -1 in Run 4! PEP-II has delivered 256 fb -1 since May Trickle injection in both rings all of the time. Near term upgrades are going well. Planned upgrades toward 2.3  are on track. SLAC to decide on down schedule in the next few months.