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

This document discusses the enhanced luminosity goals and projections for the RHIC Collider in the next 5 years, before the implementation of e-cooling. It covers assumptions, limitations, and improvements for the injectors, luminosity and background, time in store, and overall run projections. The document also provides a summary of the major improvements for RHIC.

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

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  1. Near-term machine performance— The next 5 years, before e-cooling — Wolfram Fischer Run Coordinator for RHIC Run-4 Open Meeting on RHIC PlanningBerkner Hall3 December 2003

  2. Enhanced luminosity • Enhanced Luminosity Goals (before e-cooling) • For Au-Au, average per store (4 design)L = 81026cm-2s-1 at 100GeV/u • For p-p average per store, 2 IRs (16 design)L = 61031cm-2s-1 at 100GeVL = 1.51032cm-2s-1 at 250GeVwith 70% polarization

  3. Contents • Assumptions for projections • Limitations and improvements • Injectors • Luminosity and background • Time at store • Run-4 • 5-year projections • Summary

  4. RHIC Collider Projections [annual updates based on experience gained in the previous run]

  5. 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

  6. Collider performance comparisons 14 wks 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! 14 wks M. Lamont

  7. Limitations (1) – injectors • Bunch intensity and polarization • Achieved: Au 0.7109/bunch 10mm 0.3eV·s • Booster low level rf upgrade • Additional bunch merge  1.3 109/bunch • Achieved: p 0.81011/bunch 10mm 0.3eV·s 40% pol. • Achieved: p 2.01011/bunch 20mm 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

  8. 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

  9. 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 • …

  10. 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: • 5+14 weeks Au-Au at 100GeV/u beam energy,target luminosity of 300(mb)-1 delivered • 5 weeks p development(partial warm AGS snake, gas jet, working point)

  11. Run-4 goals experimental target [after 5 weeks of start-up and ramp-up]

  12. 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

  13. 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 projected maximum

  14. 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 projected maximum

  15. Major RHIC improvements Injectors Luminosity and background Time in store New things to be filled in as we understand the machine better

  16. Summary • Enhanced Luminosity Goals (before e-cooling) • For Au-Au, average per store (4 design)L = 81026cm-2s-1 at 100GeV/u • For p-p average per store, 2 IRs (16 design)L = 61031cm-2s-1 at 100GeVL = 1.51032cm-2s-1 at 250GeVwith 70% polarization • Required • Sufficient running time in each mode [many weeks/year] • Resources to carry out improvement projects

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