PEP- II Linac Accelerator Systems Department The PEP-II B-Factory Accelerator John T. Seeman...

PEP- II Linac Accelerator Systems Department

The PEP-II B-Factory Accelerator

John T. SeemanAssistant Director

Particle and Particle-Astrophysics DivisionSLAC

DOE HEP ReviewJune 14, 2005


Topics

• Highlights of Run 5 of PEP-II

• Run plan through 2008

• How to increase the luminosity to 2.1 x 1034

• Future down work


The PEP-II Team

•

August 2004


Beam Lines


PEP-II arc section


PEP-II HER RF cavities


PEP-II Interaction Region Components near BaBar

HER

LER

Collision point

BaBar


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


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


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.


230 kV Lines

•


The cable break area

•

230 kV lines


The tree that fell (100 ft tall)

• Neighbor’s tree

Stanford tree


•

Power lineloose cables


•


String new wires by crane

•


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


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.


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


Daily Integration Record with Trickle Injection

710/pb

LER I

HER I

Luminosity


PEP-II Monthly Peak Luminosity

•


•


•

Prediction July 2003

Actual


•

Prediction April 2005

Actual

Power outage


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?)


Change of specific luminosity over mini-trains

•

Mini-trainsSpecificluminosity

Luminosity


Luminosity Equation y is the beam-beam parameter (~0.065)

Ib 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 (1033 cm-2 s-1)

*341017.2

y

byEInxL


Future luminosity increase factors

Parameter Present Future Luminosity gain ratio

Hardware and work needed

LER current 2450 mA 4500 mA Two RF stations, new IR vacuum chambers

HER current 1550 mA 2200 mA 1.61 Two RF stations, new IR vacuum chambers

y* 10.5 mm 8.5 mm 1.24 HER higher tunes, RF & power supplies work

y 0.065 L 0.043 H

0.070 L 0.055 H

1.17 Tune plane, coupling, & IR work

Total x 2.3


Overall Parameters and Goals

Parameter Units DesignBest in collision

Future 2007 goal

I+ mA 2140 2450 4500

I- mA 750 1550 2200

Number bunches

1658 1588 1715

y* mm 15-20 11 8.5

Bunch length mm 15 11-12 9

y 0.03 0.043-0.065 0.055-0.07

Luminosity x1033 3.0 9.2 21

Int lumi / day

pb-1 130 710 1300

Over five times design!Over three times design

Twice design


PEP-II Future Luminosity Parameters

x y x y n I x* y* Lumi x y

Units cm mm nm nm mA m m x1E33

LER now

32 10.5 33 1.55 1616 2450 103 4.0 9.21 0.053 0.065

LER 2007

28 8.5 47 1.80 1720 4500 115 3.9 21.0 0.065 0.070

HER now

33 10.5 60 1.30 1616 1550 139 3.7 9.21 0.052 0.043

HER 2007

28 8.5 66 1.60 1720 2200 136 3.7 21.0 0.063 0.055


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)


•

Local Chamber Area

Dots show new chamber locations.


New IP Be bellows design

•

SiC

Cooling


New Q2 Chamber Forward

•


Forward Q2 Chamber (HER/LER)

LER leg

HER leg


•

Straight HOM Bellows -Design Details

GlidCop GlidCop StubStub

Inconel Spring Inconel Spring FingerFinger

GlidCop RF GlidCop RF Shield FingerShield Finger

Welded Welded BellowsBellows

Absorbing TileAbsorbing Tile

2.75” long by .24” wide 2.75” long by .24” wide HOM Trapping SlotsHOM Trapping SlotsModes in the chamber propagate through the slots & are absorbed by the AlNiSiC.

Bellows CavityBellows CavityModes that leak past the RF shield finger and are trapped in this area still see the absorberBeam DirectionBeam Direction


New Q5 HER Chamber

•


Q5 HER details

•


HER Q4 Chambers

Q5R BPMQ4R BPM

27.5 inches14 inches

e-e-

Looking upbeam

BPM Timing BPMs

Electron BPMs

Electron BPMs

Electron BPMs

Electron BPMs


•

Q4/Q5 Bellows LayoutQ4/Q5 Bellows Layout

Q4 side, 10” Q4 side, 10” flangeflange

Q5 side 12” flangeQ5 side 12” flange

GlidCop GlidCop StubStub

Inconel Spring Inconel Spring FingerFinger

GlidCop RF GlidCop RF Shield FingerShield Finger

Welded Welded BellowsBellows

Cooling – not shownCooling – not shown

Absorbing TileAbsorbing Tile


IR Q4-Q5 bellows with HOM Absorbers


Accelerator Physics Studies Needed for 2x1034

• 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


Expected PEP-II Delivered Integrated Luminosity

End of fiscal yearTotal PEP-II Projection

Delivered

“Yearly change”

Peak

Luminosity

x 1033

FY2004 256/fb 117/fb 9.2

FY2005 338 82 10.5

FY2006 516 178 13

FY2007 722 206 20

FY2008 1097 375 21

Projection May 2005


Integrated Luminosity Goals

Now


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 2.11034 are on track.

• Goal is more than 1 ab-1 in 2008.

• Run and down schedules have been mapped until 2008.

PEP- II Linac Accelerator Systems Department The PEP-II B-Factory Accelerator John T. Seeman...

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