pep-ii now, long range, and parameter goals for 2003-2009

PEP-II Now, Long Range, and Parameter Goals for 2003-2009

John T. Seeman

For the PEP-II Team

PEP-II MAC Meeting

October 9, 2003

PEP-II MAC October 9, 2003 2

PEP-II e+e- Collider

•


PEP-II is a two ring e+e- asymmetric collider


Luminosity Equation

y is the beam-beam parameter (~0.06)

• Ib is the bunch current (1 ma x 2 ma)

• n is the number of bunches (~1050)y

* is the IP vertical beta (~12 mm)

• E is the beam energy (3.1 and 9 GeV)

*341017.2

y

byEInxL


Overall Parameters and Goals

Parameter Units DesignTypical in collision

BestFuture in 2007

I+ mA 2140 1550 2415 3600-4500

I- mA 750 1130 1150 2000

Number bunches

1658 1039 1700 1700

y* cm 15-20 12 11 6

0.03 0.06-0.09 0.10 0.11

Luminosity x1E33 3.0 6.2 6.58 20-30

Integrated lumi / day

pb-1 130 310 3951200 to 1800


PEP-II Monthly Peak Luminosity

Peak PEP-II Luminosity (x1E33) per Month

0

1

2

3

4

5

6

7

Jun-

99

Dec

-99

Jun-

00

Dec

-00

Jun-

01

Dec

-01

Jun-

02

Dec

-02

Jun-

03


PEP-II Summer 2003 Projects

• New HER # 8 RF station (+200 mA).

• New HER collimator (30 m upstream).

• Improved low level RF feedback circuits (higher I).

• More x-y BPMs in IR2 region.

• LER straight section and Arc 11 solenoid upgrade.

• Octupoles for tune shift with amplitude studies.

• Bellows fans on all LER bellows (~240)

• IR4 HOM damper


Raise HER and LER currents

• HER has seven RF stations with six in use. One missing a klystron. We will add one more station this summer.

• LER has 3 RF stations, all in use. We will add a LER station in Summer 2004.

• New low level RF controls and feedback now coming on line.

• Still too many trips of RF stations. Trip rate is the same as last year but the beam currents are 15% higher.

• Two new klystrons and two repaired klystrons should arrive in the next six months.


Lower BaBar backgrounds

• BaBar backgrounds are often good.• Backgrounds can be poor during

injection (mostly HER) and at high currents and luminosity.

• Muon IFR outer layers are often swamped.

• A new HER upstream collimator will be installed this summer.

• In LER Pb shielding will be installed upstream to reduce IFR beam spray.

• Injection studies are being planned to improve reliability.

HER horizontal collimator


Reduce the Electron Cloud Instability (ECI)

Low energy electrons in the vacuum chamber are attracted to the positron beam and cause “head-tail” instabilities. This is called ECI.

Solenoids have been shown to strongly reduce this effect in PEP-II by keeping the electrons near the chamber walls. This summer we plan to strengthen the solenoids in the straight sections (x 3 in field) so that bunches can be placed every 2 RF buckets (every 3 now). A chamber distance of about 1 km is to be wound.

ECI in the By-2 bunch pattern


Octupole Magnets (from CERN)


Future Run Plan (Highlights)

• Collide 9-10 months per year to 2009.• Five month down in Summer 2005 to install BaBar IFR

upgrades, upgrade silicon tracker and PEP-II IR.• Possible 4 month down in Summer 2007 to “rotate” the

Silicon tracker (radiation).• Aggressive hardware upgrade to PEP-II to get to a luminosity

of 2 to 3 x 1034 by FY2006-2007.• Deliver 100 fb-1 more by Summer 2004.• Record a total of 500 fb-1 by Fall 2006.


Overview plans to improve the PEP-II program

• “Post Run Summary” in July.• Restart the PEP-II Machine Advisory Committee.• Perform a Mid-Project Evaluation with PEP-II people

and outside-the-project people to refine our tasks.• Welcomed further participation of BaBar collaborators.• Develop a firm technical upgrade plan.


PEP-II and KEKB Possible Luminosity Gains (estimated by J. Seeman October 2003)

Effect PEP-II PEP-II Gain KEKB KEKB Gain

Lower y* 12 6 mm 1.5 6 6 mm 1.0

Move x tune to 0.52 In progress 1.1 Done 1.0

Move x tune to 0.505 Later 1.1 In progress 1.1

Increase currents In progress 1.8 In progress 1.3

Stronger LER solenoids In progress 1.4 In progress 1.2

X-angle or Crab cavities Not needed 1.1 2005-2006 2.0

Increased injection rate 30 60/120 1.2 Done (50 Hz) 1.0

Or Continuous injection Needs study 1.1 (1.3) Needs study 1.1

Or two bunch injection Needs study 1.1 Done 1.0

Total factor 75% of gain 4.0(5.0) 75% of gain 2.9


PEP-II Integrated Luminosity Goals

• DatePEP-II delivered goal

Loss to other programs

Net delivered

BaBar losses

Net recorded

Total recorded

(fb-1) (fb-1) (fb-1) (fb-1) (fb-1) (fb-1)

July 2003 -- -- 140 8 132 132

July 2004 116 12 104 6 98 230

July 2006 343 35 308 20 288 518


Beam Parameters

• June 2003: 1.45A x 1.1 A y*=12 mm 1034 bunches L=6.6E33• July 2004: 2.7A x 1.6 A y*=9 mm 1450 bunches L=12.1E33• June 2005: 3.6A x 1.8 A y*=8.5 mm 1500 bunches L=18.2E33• July 2006: 3.6A x 2.0 A y*=6.5 mm 1700 bunches L=23.0E33• July 2007: 4.5A x 2.2 A y*=6 mm 1700 bunches L=33.E33

• With good integration reliability:• 100 fb-1 more integrated by Summer 2004.• 500 fb-1 total integrated by Fall 2006.• About 1 to 1.4 ab-1 integrated by Fall 2009.


RF Parameters and Bunch Lengths


Major Goals for Mid-Project Evaluation Focus Groups

• Parameters:– Check for consistent parameter sets for future goals.– Can we get the luminosity in other ways? (Low emittance gets

1x1033.)– Check for instability thresholds with 1700 bunches.– How bad are the parasitic collisions?– Check beam-beam effect at low y

* and short bunches?– How do we make low alpha lattices?– ECI in by-2 bunch pattern?– Do we need an IP crossing angle in 2006?


Major Goals for Focus Groups

• Lattice/Model:

– Fix all beta-beats

– Lower y* in both rings from 12 mm to 6.5 mm.

– Raise LER x from 38.5 to 48.5 to reduce . More sextupoles?

– Raise HER x from 24.5 to 34.5 to reduce . More sextupoles?

– Can we get low y’s without changing the IR (like KEKB)?

– Would a super-conducting IR be better to low betay?


Group goals (Cont.)

• RF system:– Install HER-8 station in 2003– Install LER-4 station in 2004– Install HER-9 station in 2004– Install HER-10 station in 2005.– Total LER current = 3600 mA.– Total HER current = 2000 mA.– Reduce RF aborts from 10 per day to 0.5 per day.

• Feedback systems:– Make LLRF feedback capable of 3.6 x 2 A.– Make LFB system capable for 3.6 x 2 A with 1700 bunches.– Make TFB system capable for 3.6 x 2 A with 1700 bunches.


Group goals (cont.)

• Diagnostics: – Make all BPMs with x-y readout– Improve LER synchrotron light monitor.

• Vacuum systems:– New Q5 chambers– New Q4 chambers– New Abort windows– New Q1 chambers– New B1 chambers– New LER bellows – New LER transition chambers– New IR radial ion pumps– New HER Luminosity chamber

• :


Group goals (cont.)

• Reliability/Uptime:

– Increase peak to average luminosity from 45% to 60%.

– Reduce aborts from 10 per day to 1 per day.

– Reduce chronic event failures.

– Reduce single event failures.

• Injection:

– Increase injection rate by trickling, 60 Hz, or multi-bunches per shot.

– Reduce injection losses.

– Reduce BaBar backgrounds from injection.


Group goals (cont.)

• Machine/Detector Interface:– HER current increases by 2x.– LER current increases by 2.5x.– Luminosity increases by 4x.– Is the new IR design acceptable?

• New IR Design:– Lower y

* to 8.5 mm in 2005.– Lower y

* to 6.5 mm in 2006.– Add IP crossing angle of 4 mrad in 2006? (Beam-beam says no!)– Beam stay clear issues?– Permanent magnets or Superconducting?


Accelerator Improvement Projects

• Likely Near Term AIP Projects• PEP-II HER9 RF Station FY2004• PEP-II RF new windows FY2004• PEP-II New Sextupoles for Higher Tunes FY2004• PEP-II Quad Power Supply Upgrade for Higher Tunes FY2004• PEP-II Longitudinal Feedback Power Amp Upgrade FY2004• PEP-II X-Y BPM Upgrade FY200-2005• PEP-II New LER Synchrotron Light Monitor FY2004• PEP-II IR Low Beta Quad Upgrade FY2004-2005• PEP-II IR2 New Shield Wall for IFR FY2004• PEP-II Support Tube Removal Hardware Upgrade FY2004• PEP-II Faster LER Abort kicker FY2004• PEP-II IR2 New Q1L and Q1R Chambers FY2004-2005• PEP-II IR2 New B1L and B1R Chambers FY2004-2005• PEP-II IR2 New Radial Ion Pumps FY2004-2005• PEP-II IR2 New Q2L and Q2R Chambers FY2004-2005


AIP Project (Cont)

• PEP-II IR2 New Q4L and Q4R Chambers FY2004-2005• PEP-II IR2 New Q5L and Q5R Chambers FY2004-2005• PEP-II IR2 New Luminosity Chamber FY2004-2005• PEP-II LER photon stop temperature monitoring FY2004• PEP-II IR2 New High Power Dump FY2005• PEP-II Upgrade of Bong Collimator FY2005• PEP-II LER New Abort Window FY2005• PEP-II New Transverse feedback chambers FY2005• PEP-II New LER High Power Bellows FY2005-2006• PEP-II New Longitudinal Feedback System FY2006• PEP-II LLRF Upgrade FY2006• PEP-II New Transverse Feedback System FY2006• PEP-II LER5 RF Station FY2005-2006• PEP-II HER10 RF Station FY2006-2007• PEP-II Controls and Diagnostics for Better Injection FY2006-2007• PEP-II Better LER IR vacuum for backgrounds FY2006-2007


Top Eight List of Issues

• Improve the longitudinal beam and RF system stability.• Reduce injection time and injection backgrounds.• Lower y* from 12 to 9 to 6 mm.• Increase beam currents and number of bunches (x1.7).• Understand and reduce parasitic collisions.• Develop low “alpha” lattices for both rings.• Reduce unscheduled outages (now about 10%)• Strengthen our support groups.


Conclusions

• PEP-II has exceeded twice its design luminosity and three times its design integrated luminosity per day.

• PEP-II must continue to show strong improvements to keep up with the competition.

• A parameter set and integration plan has been developed to reach our goals. Several issues remain to be resolved.

• An aggressive construction and installation plan covering three to four years has started.

pep-ii now, long range, and parameter goals for 2003-2009

Documents

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