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Near-term machine performance— The next 5 years, before e-cooling —

Wolfram FischerRun Coordinator for RHIC Run-4

Open Meeting on RHIC PlanningBerkner Hall

3 December 2003

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Enhanced luminosity

• Enhanced Luminosity Goals (before e-cooling)

– For Au-Au, average per store (4 design)

L = 81026cm-2s-1 at 100GeV/u

– For p-p average per store, 2 IRs (16 design)

L = 61031cm-2s-1 at 100GeV

L = 1.51032cm-2s-1 at 250GeV

with 70% polarization

Wolfram Fischer 3

Contents

1. Assumptions for projections

2. Limitations and improvements• Injectors• Luminosity and background• Time at store

3. Run-4

4. 5-year projections

5. Summary

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RHIC Collider Projections

[annual updates based on experience gained in the previous run]

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Assumptions for projections

• 2 weeks for cool-down, 1 week for warm-up• For each mode (Au-Au, p-p, d-Au, etc.)

– 2 weeks of set-up [only machine operation]

– 3 weeks of ramp-up [machine operation with experimental set-up during owl shift]

– Continuous luminosity development in production[over 14 weeks during the day]

• Minimum and maximum projections– Minimum repeats demonstrated performance– Maximum requires completion of improvement projects– Maxima ambitious, likely outcome between min and max

• For 5-year luminosity projections– 5+14 weeks of operation in each mode– Only 2 collisions in p-p operation

Large penalty for frequent mode switches

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Collider performance comparisons

14 wks

14 wks

M. Lamont

14 wks

Common features - long runs (>14 wks/yr)- non-linear increase after shut-downs- many years for substantial increases

RHIC is of comparable complexity!

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Limitations (1) – injectors

• Bunch intensity and polarization– Achieved: Au 0.7109/bunch 10m 0.3eV·s

• Booster low level rf upgrade

• Additional bunch merge 1.3 109/bunch

– Achieved: p 0.81011/bunch 10m 0.3eV·s 40% pol.

– Achieved: p 2.01011/bunch 20m 0.5eV·s 20% pol. ?

• AGS warm helical snake in Run-4 40% pol. in RHIC

• AGS cold helical snake in Run-5 70% pol. in RHIC

• Later– New solenoid for polarized source

– 2nd AGS cold helical snake?

• EBIS (Electron Beam Ion Source)

– Earliest 2008, see presentation by J. Alessi

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Limitations (2) – luminosity and background

• Vacuum problems with high intensities Test of NEG coated beam pipes (low SEY, pumping) Solenoids

• Losses during ramp Better orbit, tune, coupling, chromaticity control PLL tune meter, tune feedback

• Experimental background Secondary collimators (½ this year, ½ next) Shielding (PHENIX, BRAHMS this year)

• Instabilities Improved chromaticity control, coherence monitor Transverse damper

• Intra-beam scattering (Au-Au) Stochastic cooling development e-cooling for RHIC II

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Limitations (3) – time in store

• Reduction of quench occurrences Reduce abort kicker pre-fires Avoid excessive beam losses

• Improve operational efficiency Faster down ramps (gain about 2 days/run) More automation at beginning of store (steering, collimation, gap cleaning) Better software tools for ramp tuning Faster injection set-up

• Reduce system downtime Eliminate ice ball maintenance at current leads Improve corrector power supply reliability Improve AtR reliability

• …

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Run-4 goals

• President’s budget allows for 27 weeks of cryogenic operation (need 3 weeks for cool-down and warm-up)

• Run-4 modes:

1. 5+14 weeks Au-Au at 100GeV/u beam energy,target luminosity of 300(b)-1 delivered

2. 5 weeks p development(partial warm AGS snake, gas jet, working point)

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Run-4 goals

experimental target

[after 5 weeks of start-up and ramp-up]

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Current status RHIC Run-4

• 5-week start-up/ramp-up period started on Monday 12/1/03

• Reached 0.8·109/bunch in Blue on Monday

• Blue: Injected 111 bunches with 0.5·109/bunch (pressure rise in bi8 and bo2, up to 10-6 Torr)

• Yellow: Injected 111 bunches with 0.1·109/bunch (no pressure rise observed)

• First ramps this morning– 6 bunches each

– 50% Blue transmission

– 40% Yellow transmission

Today at noon

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Projected 5-year Au-Au luminosity evolution

Assume- 14 weeks production in every year- linear luminosity increase during run- 4 experiments- completion of improvements

achieved projectedmaximum

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Projected 5-year p-p luminosity evolution

Assume- 14 weeks production in every year- linear luminosity increase during run- only 2 experiments- completion of improvements

achieved projectedmaximum

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Major RHIC improvements

Injectors

Luminosity and background

Time in store

New things to be filled in as we understand the machine better

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Summary

• Enhanced Luminosity Goals (before e-cooling)

– For Au-Au, average per store (4 design)

L = 81026cm-2s-1 at 100GeV/u

– For p-p average per store, 2 IRs (16 design)

L = 61031cm-2s-1 at 100GeV

L = 1.51032cm-2s-1 at 250GeV

with 70% polarization

• Required– Sufficient running time in each mode [many weeks/year]

– Resources to carry out improvement projects