1 Near-term machine performance — The next 5 years, before e-cooling — Wolfram Fischer Run Coordinator for RHIC Run-4 Open Meeting on RHIC Planning Berkner Hall 3 December 2003

Wolfram Fischer 2 Enhanced luminosity Enhanced Luminosity Goals (before e-cooling) –For Au-Au, average per store (4  design) L = 8  cm -2 s -1 at 100GeV/u –For p  -p  average per store, 2 IRs (16  design) L = 6  cm -2 s -1 at 100GeV L = 1.5  cm -2 s -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 year projections 5.Summary

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

Wolfram Fischer 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

Wolfram Fischer 6 Collider performance comparisons 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!

Wolfram Fischer 7 Limitations (1) – injectors Bunch intensity and polarization –Achieved: Au 0.7  10 9 /bunch 10  m0.3eV·s Booster low level rf upgrade Additional bunch merge  1.3  10 9 /bunch –Achieved: p 0.8  /bunch 10  m0.3eV·s 40% pol. –Achieved: p 2.0  /bunch 20  m0.5eV·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 –2 nd AGS cold helical snake? EBIS (Electron Beam Ion Source) –Earliest 2008, see presentation by J. Alessi

Wolfram Fischer 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

Wolfram Fischer 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 …

Wolfram Fischer 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: 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)

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

Wolfram Fischer 12 Current status RHIC Run-4 5-week start-up/ramp-up period started on Monday 12/1/03 Reached 0.8·10 9 /bunch in Blue on Monday Blue: Injected 111 bunches with 0.5·10 9 /bunch (pressure rise in bi8 and bo2, up to Torr) Yellow: Injected 111 bunches with 0.1·10 9 /bunch (no pressure rise observed) First ramps this morning –6 bunches each –50% Blue transmission –40% Yellow transmission Today at noon

Wolfram Fischer 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

Wolfram Fischer 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

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

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