PEP-II Overall Plans

Accelerator Systems Division

PEP-II Overall Plans

John Seeman for the PEP-II TeamParticle and Particle-Astrophysics Directorate

Stanford Linear Accelerator Center

PEP-II MAC MeetingNovember 15, 2007


Topics

• PEP-II MAC meeting information

• Charge to the MAC Committee

• MAC agenda and talks:http://www.slac.stanford.edu/grp/ad/pep-ii/MAC-Review/MAC-Nov2007/

• Highlights of Run 6.

• Main activities for Fall 2007 down

• Plan for Run 7 in FY2008

• Shut down planning


PEP-II MAC Information

• In an emergency:– Fire: Leave the building by the nearest safe exit– Earthquake: Duck, cover, then leave the

building– Others: Best to leave the building; meet outside

• Meeting Rooms: – Thursday am: Kavli Auditorium (Kavli)– All the rest: Redwood Room (ROB)

• Dinner Thursday evening (7 pm)– Logan Davis or Regina Matter will have maps.


Charge• The combined team of PEP-II and BaBar has amassed a

large data set in the past nine years, reaching a total of 500 fb-1. To keep the experiment viable, this team needs to reach a total of about 750 fb-1 in the next 10 months (50% more). This requires increasing the performance in a commensurate way.

• With regard to the PEP-II facility, the Laboratory is requesting the Machine Advisory Committee (MAC) to:– a) Critique the plans for maximizing the integrated luminosity in

Run 7 which goes from December 2007 through September 2008.– b) Appraise the luminosity improvement plans to reach the peak

luminosity goal in the spring of 2008. – c) Review the near-term focus and schedule for accelerator physics

studies as they contribute to maximizing the integral for Run 7.


The PEP-II Team

• Accelerator Systems DivisionSLAC Support GroupsBaBarMachine Advisory Committee

1x1034


The PEP-II Team• Run Coordinator: M. Sullivan• Beam dynamics: F-J. Decker, S. Heifets, A. Kulikov, U. Wienands• IR: S. Ecklund, W. Wittmer, M. Weaver• Lattice: Y. Cai, Y. Yan, G. Yocky, M. H. Wang• RF: A. Hill, H. Schwarz, D. Van Winkle, V. Pacak, K. Bertsche• HOM: A. Novokhatski, S. Weathersby, K. Ng• Feedback: J. Fox, A. Young, R. Akre• Instrumentation: A. Fisher, M. Petree, W. Cheng, M. Browne, R.

Chestnut• Vacuum: S. DeBarger, M. Dormiani, D. Kharakh, N. Kurita, S.

Metcalfe, R. Pope, N. Reeck• Systems: M. Zurawel, P. Smith, K. Burrows, T. Graul, T. Galetto, A.

Baker• Operations: Operators, R. Erickson, M. Stanek, P. Schuh, W. Colocho,

B. Allen• Much appreciated help from: Power Conversion, Software, Controls,

CEF, Metrology, Klystron, Radiation Physics, Beam Physics, BaBar


Run 6 New Advances for PEP-II

• Two new HER RF stations in, working and are ready for higher currents.

• New skew quad fix for IR2 LER x-y coupling found and implemented. Specific luminosity is higher. More luminosity gain is expected in the future. (Decker, …)

• Fast dither IP feedback in and working with supervision (Sullivan, Fisher, …).

• Vertical vibration in IR support tube damped with BaBar’s help. Thanks.


Run 6 January-September 2007 Major Problems

• Late start from the Fall 2006 down• Vacuum leak in HER IR Q4 chamber• Damaged coils on IR Quadrupole Q2 • Bunch Injection Controller problems occurred .

New system was installed.• VAT seal near luminosity chamber leaked.• HER flex-flange seals show discharges• More PG&E AC power dips than normal.


HER arc 5 RF seal at 6122




New month and 30 day records

August 2007 was our Best month


PEP-II Parameter Goals have not changed!

Parameter Units Design Present best 2008 goal

I+ mA 2140 2940 4000

I- mA 750 1940 2200

Number bunches

1658 1722 1740

y* mm 15-20 10 8-8.5

Bunch length mm 15 11-12 8.5-9

y 0.03 0.047-0.065 0.054-0.07

Luminosity x1033 3 12 20

Int lumi / day

pb-1 130 911 1300

7 times design4 times design


Fall 2007 Down Activities (September 4-December 3)

• Finish LER BPM replacement. (Done)

• Add 5 HER Arc HOM bellows. (To start soon)

• Add 12 LER IR2 HOM bellows. (To start soon)

• Replace about 192 HER Arc flex-flange RF “Omega Seals”. (5/6 done)

• Install two new LER Q5 chambers in IR2. (Done)

• Install repaired HER Q4L chamber. (Done)


New HOM absorbers work and more are being built.

Absorbing tiles

NovokhatskiWeathersbyKuritaReeck


General Overall Plan for Run 7 (Dec 2007-Sept 2008)

• Start the linac and PEP-II in December.• Run through the holidays.• Do more machine studies (MD) early to increase

luminosity at the beginning of the run.• Keep in any new accelerator configuration with a

luminosity improvement and then keep running!• Find the optimum luminosity condition by early

spring.• Run through September with best steady state

conditions.


Proposed Run Plan December-March

• In general collide for BaBar as much as possible!• December goals:

– Scrub both rings while colliding.– Reestablish 0.8x1034 parameters.– Holiday running (minimal supervision)

• January-March goals:– Establish 1.7x1034 parameters.– Establish HER 90 degree lattice.– LER lower vertical emittance using IR skew quads– Increase HER/LER RF voltages.– Try lowering y*s in collision.– Increase beam currents


Proposed April-September Plan

• Goals: ~April 1 start a steady state run.– Collide for BaBar constantly.– Establish 1.7 to 2.0 x 1034 parameters gradually.– No MDs except for tuning during collisions or

for very good possibilities.


Luminosity Projection

• We make luminosity projections using:– Known running months– Past running efficiencies (~55% with many

MDs and ~68% with a few MDs)– Expected gains in peak luminosity (1.22.0x

1034)– Known downtimes


Sept 5, 2007

PEP-II projected luminosity spreadsheet


•

Now


PEP-II Shut Down

• PEP-II will stop producing data for BaBar on September 30, 2008, about ten months from now.

• PEP-II and BaBar will then transition rapidly into a “Minimal Maintenance State (MMS)” which takes just over a year.

• In the medium time frame, PEP-II will be at this MMS with some effort going into tunnel maintenance, safety lighting, electrical safety and mechanical safety. Valuable items will be preserved.

• For long term, D&D of PEP-II is being studied. A DOE review held in early August 6-7, 2007.


Conclusions

PEP-II accelerator in Run 6 was more difficult than planned but the run ended well.

The luminosity will be ramped as fast as possible in Run 7.

PEP-II will integrate as much luminosity as possible.

Execution of the Fall 2007 shut down is going well.

Upgrades towards ~21034 will soon be done with the aim of 257 fb-1 more to 757 fb-1.

PEP-II will turn off September 30, 2008.

Documents

PEP-II Overall Plans