SLAC Accelerator Department The PEP-II Accelerator Status and General Plans John T. Seeman Assistant Director of the Technical Division Head of the Accelerator

SLAC Accelerator Department

The PEP-II AcceleratorStatus and General Plans

John T. SeemanAssistant Director of the Technical Division

Head of the Accelerator DepartmentSLAC SPC MeetingDecember 3, 2004


Topics

• Highlights of Run 4 of PEP-II

• Summer 2004 down

• General future plans


Contributors to PEP-II• SLAC• LBNL• LLNL• With help from:

– IHEP, Beijing, China– BINP, Novosibirsk, Russia– INFN, Frascati, Italy– CEA, Saclay, France– IN2P3, Paris, France– Caltech– BNL– Many people from the BaBar Collaboration– Visitors from CERN, DESY, Cornell, FNAL, KEK, …


PEP-II e+e- Collider• Use the SLAC linac as

upgraded for the SLC for the injector.

BaBar Detector

FeedbacksDiagnostics

LERRF476 MHz

HERRF476 MHz

3.1 GeV positrons x 9 GeV electronsC = 2200 m


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


Improvements in FY2004

– Peak luminosity: 6.6 9.21033

– 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)– Icurrent 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


Daily Integration Record with Trickle Injection

710/pb

LER I

HER I

Luminosity


Peak luminosity of 9.21 x 1033

RecordPeakLuminosity


Trickle injection at the B FactoriesBest shift, no trickle

PEP-II: ~5 Hz continuousKEKB: at ~5-10 min intervals

Best shift, LER only trickleNov 2003

Best shift, double trickleMar 2004

PEP-II LumiHER currentLER current


Trickle Charge: Length of Fill

. ..

0 100 200 3000.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

t fill

(h)

Time since 1-Sep-04, 00:00 (days)

PEP Run 4 Average Length of Fill

0.60.8

2.3

Sep

Oct

Dec

Nov

Jan

Feb

Mar

Ap

r

May

Jun

Au

g

Jly


PEP-II Run Time Dist. FY 04M. Stanek

Pre-trickle LER-trickle Double-trickle


•


PEP-II Performance Measure: Peak Luminosity


Run 1

Run 2

Run 3

Run 4

CD4

Design Performance



•

Total >240 fb-1!


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


New IR2 Shield Wall for BaBar IFR


LER NEG Test chamber


Lab test data of NEG outgassing as a function of temperature

LER NEG Pump Temperatures

Upstream LER side

NEG Pressure vs NEG Temperature

0

1

10

100

1000

10000

0 100 200 300 400 500 600 700

NEG temperature deg F

NE

G p

ress

ure

(n

To

rr) 350 °F


Existing 3082 chamber

BPM

BPM

Chamber support

Cooling bar

NEG plenum

NEG heater

Quad extrusion


Chamber showninverted and plenum not shown for clarity

SiC HOM absorber


New bellows design with HOM absorber

• KuritaNovokhatskiWeathersby


IR Vacuum Chambers

Vertex Bellows

Q1/Q2 Bellows


VTX Bellows Cooling Installation


Forward VTX BLWS Cooling


Thermo Model

(May 2001) for 100

Watts Power input behind

fingers.


New Be bellows design

•

SiC

Cooling


HER Single-Bunch Synchroscan Data at 16 MV


Comparing Single-Shot and Synchroscan Data

LER e+


New LER Synchrotron Light Monitor

Improved resolution

Single bunch capabilities



Luminosity versus Crossing Angle

• Normalized Lsp vs. e- angle

0.75

0.80

0.85

0.90

0.95

1.00

1.05

-1000 -500 0 500 1000

XP[e-] (murad)

Lsp

/ L

sp(X

P=

0)

by-4, msrd

by-4, fit

sp. by-2, msrd

sp. by-2, fit

Without parasitic crossing

Withparasitic crossing


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

Parasitic x 3.22 mm 3.80 mm 1.08 B1 magnet change (?)

Total x 2.52


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* cm 15-20 11 8.5

y 0.03 0.045, 0.07 0.055-0.08

Luminosity x1033 3.0 9.2 23

Integrated lumi / day

pb-1 130 710 1600

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 47 1.80 1720 4500 115 3.8 23.0 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 66 1.60 1720 2200 136 3.6 23.0 0.063 0.055


Expected PEP-II Delivered Integrated Luminosity

Delivered as of end of fiscal year PEP-II Projection “Delta”

FY2004 256/fb 117/fb

FY2005 387 131

FY2006 528 141

FY2007 821 293

FY2008 1156 335

FY2009 1501 345

FY2010 1847 346


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 and add an IR BPM

• Upgrade several high-power IR vacuum chambers (Be bellows, 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


Conclusions

• PEP-II has reached a luminosity of 9.21033/cm2/s.

• PEP-II has delivered 710 pb-1 in one day.

• PEP-II has delivered over 117 fb-1 in Run 4!

• PEP-II has delivered over 256 fb-1 since May 1999.

• Trickle injection in both rings all of the time.

• Near term upgrades are going well.

• Planned upgrades toward 2.31034 are on track.

• Progress on studying a Super-B-Factory.

Documents

SLAC Accelerator Department The PEP-II Accelerator Status and General Plans John T. Seeman Assistant Director of the Technical Division Head of the Accelerator