SLAC Accelerator Department PEP-II Future Plans and Parameters 2004-2010 John T. Seeman PEP-II MAC Meeting December 13, 2004

SLAC Accelerator Department

PEP-II Future Plans and

Parameters 2004-2010

John T. Seeman

PEP-II MAC Meeting

December 13, 2004


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, …


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


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


Operational 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


PEP-II Performance Measure: Peak Luminosity


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


Run 1

Run 2

Run 3

Run 4

CD4

Design Performance


•



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

KozaneckiSullivanCai


Beam-Beam Observed and Simulated

• Specific luminosity vs. LER bunch current

3.0

3.5

4.0

4.5

5.0

5.5

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

LER bunch current (mA/b)

Sp

ecif

ic lu

min

osi

ty (

1E30

mA

^-2

b^

-1)

msrd (16 Mar 04)

simulated

Data: by-4 pattern exc. highestL/H ratio = 1.6

KozaneckiSullivanCaiNarskyDynamic

beta effects

Beam-beam limit effects


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.


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


Windings finished for ECI reduction


LER NEG Test chamber


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 Longitudinal Feedback Kicker Assembly


New transverse kicker electrodes


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


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 1720

y* mm 15-20 11 8.5

y 0.03 0.045, 0.06 0.055-0.07

Bunch length mm 12 10-12 8.5

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


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 0.06 L 0.045 H

0.070 L 0.055 H

1.17 Tune plane, coupling, & IR work, vertical emittance

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

Total x 2.52


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


HER Single-Bunch Synchroscan Data at 16 MV

HoltzappleFisherNovokhatski


Comparing Single-Shot and Synchroscan Data

LER e+


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: 0.0024 0.0017

• LER bunch length: 11.8 mm 8.7 mm• HER bunch length: 11.4 mm 8.4 mm


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 2005-2006 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 2007-2009 same as above

• Option 2:– Run through 2005-2006 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 2007-2009 same as above


VTX Bellows Cooling Installation: Key issue in the future!


New Be bellows design

•

SiC

CoolingLangton


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

Fivemonthdown


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


Detailed PEP-II upgrade list

• IR2 new Q2 chamber Apr-05• Transverse digital feedback Apr-05• RF woofer link May-05• IR2 Q2 bellows Jul-05• ST Be bellows Jul-05• ST radial ion pump Jul-05• ST new BPM Jul-05• IR2 HER Q4L Jul-05• IR2 HER Q4R Jul-05• IR2 HER Q5L Jul-05• IR2 HER Q5R Jul-05• IR2 HER Q4-5 bellows Jul-05• IR2 LER Q4-5L Jul-05• IR2 LER Q4-5R Jul-05• LER Abort spoiler Jul-05• LER new high power bellows Jul-05• PEP-II tunnel network upgrade Jul-05• RF station HER 10 Aug-05• HER tune power supply upgrade Aug-05• RF comb-2 project Dec-05• RF klystron linearizer Jan-06• RF station LER 5 May-06• IR HER HOM absorbers May-06• IR LER HOM absorbers May-06• IR HER new high power dump May-06• IR New HER frangible links May-06• IR new LER frangible links May-06• IR new HER 12 m transition May-06• IR new NEG chamber upgrades May-06• New longitudinal feedback system May-06

Project Time early to install


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 117 fb-1 in Run 4!

• PEP-II has delivered 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.

• SLAC to decide on down schedule in the next few months.

Documents

SLAC Accelerator Department PEP-II Future Plans and Parameters 2004-2010 John T. Seeman PEP-II MAC Meeting December 13, 2004