SLAC Accelerator Department

PEP-II Status and Future Plans

Nadine Kurita
February 22, 2005

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Table of Contents• Performance Summary• 2004 Run• 2005 Run• Long Term Goals

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PEP-II arc section

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PEP-II HER RF cavities

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PEP-II Interaction Region Components near BaBar
LER
HER

BaBar

Collision point

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PEP-II Performance Measure: Peak Luminosity

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Run 4

Run 3
Run 2Run 1Design PerformanceCD4

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Luminosity versus Crossing Angle•-Normalized Lsp vs. e angle
1.05

Kozanecki
SullivanCai

Without
parasitic
crossing

Lsp / Lsp(XP=0)

1.00
0.95

0.90

0.85

With
parasitic
crossing

by-4, msrd
by-4, fit

0.80

sp. by-2, msrd
sp. by-2, fit

0.75
-1000

-500

0XP[e-] (murad)

500

1000

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Operational Improvements in FY2004– Peak luminosity: 6.6 9.2×1033– 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)- βy* of 12 10.5 mm– All data now taken in trickle charge mode
• Both beams: LER in November, HER in MarchSLAC Accelerator Department

PEP-II Run Time Dist. FY 04• Average delivery: 65%

M. Stanek• Average tuning+injection: 17%
Pre-trickle

LER-trickle

Double-trickle

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Major Contributors to Performance•Trickle Charge raised the average luminosity– with little doubt the single biggest success…

•Rf/LFB Improvements raised current & pk lum– 6-station -> 8 station running in HER– Increased HER current to 1550 mA– Increased LER current to 2450 mA– Shorten HER bunch length by raising HER RF voltage (14.6 to 16.8 MV)– Shorten LER bunch length by raising LER RF voltage (HOM heating)– Commissioned LGD Woofer in HER•

By-2 Pattern Commissioning: more bunches•

Lattice Improvement– HER steering: lower y dispersion– ßy* reduction from 12 mm to 10 mm in both rings– Improve online tools and lattice corrections (orbit, dispersion …)

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Run 4 Major Issues• IR 2 vacuum-related problems/HOM
heating– VAT vacuum gate valve failed, replacedby spool– NEG heating

SiC HOM absorber• Limited LER beam current• Limited LER bunch length• HER longitudinal instabilities– fixed with LGD Woofer• Beam currents limited by RF stability– Mostly in the HER– Also in the LER because we were not able
to raise the RF voltage

plenum not shown forclarity

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LER upstream NEG work
• This summer:– We took out the nine NEGs with “c type” screens andinstalled a small HOM absorber in each cavity– The total length of NEG pumping that was removed is
5.5 m out of a total of 40.4 m– We removed the two movable collimators– We removed the Q4 NEG and have replaced it with a
HOM absorber (another 1.6 m of pumping)– We have added extra pumping at the port between theupstream LER Q4 and Q5 chambers– In addition, we have added extra screening to the ionpumps in this region

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Summer 2004 PEP-II Improvements• IR2 south forward shield wall: Backgrounds• Added 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

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Windings finished for ECI reduction

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New Longitudinal Feedback Kicker

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New transverse kicker electrodes

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Run 5 Status• PEP was within 5 days of final lockup whenwork at SLAC was halted by our Director.
• SLAC has been working hard on re-evaluating
and adapting our safety procedures.
• PEP-II Validation complete by February 24.
• Turn on in March.
• Run through the summer with a 1 month down.
– Goal: Double our total integrated luminosity.

SLAC Accelerator DepartmentValidation Process• A serious electrical accident occurred on October 11, 2004
(arc-flash).
• Time period October 2004 through February 2005 used foremployee training and safety procedure upgrades.
• Type A Investigation Report completed December 2004.
• Corrective Action Plan produced (draft in January andfinal in February).
• Linac and PEP-II Proposed Restart Plan produced for theRestart Validation Team January 20, 2005.
• Validation process started January 24, 2005.
• Validation process closeout February 24, 2005.
• There will be some additional hardware and procedure
rework needed following the closeout taking a few weeks.

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Validation Team Sub-Topics in Review••••••••••••••••“Safety Comes First” Training
Implementation of New Electrical Bulletins
BaBar User Safety
Radiation Safety
Electrical Safety
Detector Operation Procedures
Hoisting and Rigging
Accelerator Operations and MaintenanceIntegrated Safety Management System (ISMS) Implementation
Other Departments Management
Training Accelerator Personnel
OSHA Audit Issues
1999 Linac Safety Review
2000 PEP-II Accelerator Audit
2004 BaBar Operations Review
2004 Linac Safety Review

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Run 5 Strategy• Most luminosity will come from higher currents– 3.3 A on 1.8 A by summer 2005 in 1720 bunches• We will be pushing the rf voltages both rings– Reduce bunch length but also increase stability margins• We will further reduce ßy* in both rings– Presently we have 10.5 mm,– Would like to go towards 9 mm
– Worthwhile even at present bunch length• We will raise the bunch currents– Only way to increase beam current after filling by-2pattern– This may well require us to turn on the LER wiggler

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PEP-II Long Range Beam Parameters Goals• April 2004: 2.3A x 1.4 A βy*=11 mm 1555 bunches L=8.4E33• July 2004: 2.5A x 1.6 A βy*=10 mm 1600 bunches L=9.2E33• June 2005: 3.3A x 1.8 A βy*=9 mm 1700 bunches L=15E33• July 2006: 3.9A x 2.0 A βy*=8 mm 1720 bunches L=20E33• July 2007: 4.5A x 2.2 A βy*=8 mm 1720 bunches L=24E33• With good integration reliability and trickle injection:• 117 fb-1 more integrated from Summer 2003 to Summer 2004.
• 530 fb-1 total integrated by Fall 2006.
• 1000 fb-1 total integrated by Fall 2008

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Projected PEP-II Integrated Luminosity (fb-1)
2000…and again

1600
1400

Doubled again

1200
1000

Data
doubled800
600

Limits of PEP-II
improvements

400

Searching for evidence of New Physics inCP Violation and Rare Decays

200Jul-10Jan-10Jul-09

Jan-09Jul-08Jan-08

Jul-07

Jan-07

Jul-06

Jan-06

Jul-050Jan-05

Integrated Luminosity [fb -1]

1800

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Overall Parameters and GoalsParameter

Units

DesignBest incollision

Future2007 goal

I+mA

2140

2450

4500

INumberbunches
βy*

mA

750

1550

2200

1658

1588

1720

15-20

118.5mm0.03

ξy0.045, 0.06 0.055-0.07

Bunch lengthmm

1210-12

8.5

Luminosity

x1033

3.0

9.2

23

Integrated
lumi / day

pb-1

1307101600

Over three times design

TwicedesignOver five times design!

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Future luminosity increase factors
Parameter

Present

FutureLER current

2450 mA

4500 mA

HER current

1550 mA

2200 mA

1.61

Two RF stations, new IR
vacuum chambers

βy*10.5 mm

8.5 mm

1.24

HER higher tunes, RF &power supplies work

ξy0.06 L
0.045 H

0.070 L0.055 H

1.17

Tune plane, coupling, & IR
work, vertical emittanceParasitic Δx

3.22 mm3.80 mm

1.08

B1 magnet change (?)

Total

Luminosity gain Hardware and work
ratio
neededTwo RF stations, new IR
vacuum chambers

x 2.52SLAC Accelerator Department

Expected PEP-II Delivered Integrated Luminosity
Delivered as of end of fiscal year

PEP-II Projection“Delta”

FY2004

256/fb117/fb

FY2005387131

FY2006528141

FY2007821

293

FY20081156335

FY20091501

345

FY20101847346

Fivemonthdown

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Major 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 (TBD)• Upgrade several high-power vacuum chambers (Q4, Q5,Q2 bellows, LER abort window, absorber bellows)• HER lattice upgrade for lower momentum compaction andshorter bunches• New RF comb filters• New klystron linearizer• New transverse digital feedback processors

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Conclusions• PEP-II has reached a luminosity of 9.2×1033/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 2.3×1034 are on track.

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End of Presentation