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Status of Studies for 2004 Run

Status of Studies for 2004 Run. Full document on the web http://www.star.bnl.gov/protected/heavy/www/proposals/onium.pdf Estimated Production Rates Trigger Implementation, Efficiency and Rejection Power Simulations and Tests in d+Au and p+p Prospects for Measurements in Au+Au

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Status of Studies for 2004 Run

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  1. Status of Studies for 2004 Run • Full document on the web • http://www.star.bnl.gov/protected/heavy/www/proposals/onium.pdf • Estimated Production Rates • Trigger • Implementation, Efficiency and Rejection Power • Simulations and Tests in d+Au and p+p • Prospects for Measurements in Au+Au • Plans and Beam Use

  2. Production Rates • Rates are • per event, into e+e-, per unit rapidity at y=0 • Ok, how many do we see? • Acceptance, centrality selection, offline cuts… • J/Y: Requiring Eelectron>1.2 reduces the signal

  3. Production Rates II U Yield: 0.046 U e+e-, p>3 GeV per 1M min-bias events 0.19 U e+e-, p>3 GeV per 1M 10% central events (Triggered event ~ central) J/y Yield: 24 J/y e+e-, p>1.2 GeV per 1M min-bias events 98 J/y e+e-, p>1.2 GeV per 1M 10% central events Include: - fAB (hard fraction) - 1 unit  4p - Acceptance (3/4 Barrel) - momentum cut

  4. Simulations for Au+Au @ 200 GeV • Background • Hijing Minbias • Signal • Pythia; settings tuned for J/Y, modifications for U • Processed Background and signal in GSTAR • Mixed 1 quarkonium event with 1 Hijing event • Done at ZEBRA bank level (M. Potekhin) • Run algorithms • Hijing dataset : Background Rejection Power • Hijing + quarkonium : Trigger Efficiency

  5. EMC Topology Trigger • Divide f into 6 sections • Find a tower above a threshold • Look in the 3 opposite sections in f • If another tower above threshold, trigger.

  6. J/y Trigger: L0 Efficiency and Rejection Rejection Efficiency • Cutting at E=1.2-1.4 GeV is the region where we can work. • Less than that: • Tower calibration • No rejection power • More than that: • Little signal left. Efficiency is 10% at 1.6 GeV

  7. J/y Trigger: L0 Efficiency and Rejection No free lunch: High rejection only for peripheral events. Most signal in central events. 98% of the yield is in top 60% central.

  8. U Trigger: L0 Efficiency and Rejection Compare 2 approaches at L0, the topology trigger and the single High-Tower trigger.

  9. U Trigger: 1/Rejection vs Efficiency High-Tower trigger at L0 gives better efficiency for the same rejection power. Decision: use High-Tower at L0 for the upsilon trigger.

  10. J/y: L0 & L2 Efficiency and Rejection Most of the work is done by the topology trigger. Again, high rejection only for peripheral events.

  11. J/y: L0 & L2 Efficiency and Rejection For central collisions, every event fires Trigger works for low multiplicity, where yield is small. Not much to gain…

  12. U Trigger: L2 Efficiency and Rejection Using High-Tower at level 0 and L2 fast invariant mass: Sample the parameter space of the triggers in tandem. Minimum Bias Central Can achieve rejections of 103 keeping the efficiency above 80%.

  13. U Trigger Performance Trigger works beautifully. Large rejection power and good Efficiency. The problem is that there is not much signal! Need Luminosity!!

  14. Putting it all together: J/Y Rates Rejection is good only in peripheral trigger. Yield is small in peripheral. Trigger enhances by only a factor ~2 there. Killer: Would require 14% of STAR’s bandwidth Simply take minbias and central triggers, obtain a good sample. }

  15. U Rates U Trigger enhances yield by more than a factor of 10. Trigger works! Even at the highest L, L0 Rate is ~100 Hz L2 Rate is ~ 3 Hz Low rate. L2 Rate can be reduced by ~3 keeping efficiency high Room to move.

  16. Heavy Quarks in Run IV: Charm • J/Y Trigger works only in peripheral • Very well suited for UPC (F. Meissner) • Yield is small (2% in 100-60% bin) • Background rate is high • Would require 14% of STAR’s bandwidth • Given this, enhancement of only a factor of 2. • We will not request a dedicated trigger. • J/Y Analysis will rely on large minbias and central data sets. • 50 x 106 minbas + 50 x 106 central • 3 s signal + 5 s signal in central • Based on very conservative estimates on background rejection (significance ~ e/h)

  17. Heavy Quarks in Run IV: Beauty • Trigger looks promising • Efficiency can be kept above 85% • Rates are low!! • Take advantage of full luminosity • Same applies to ALL rare triggers (High-Tower) • Shift crews need to be FAST. • Will rely on L3 Express stream for quick turnaround • Conservative estimate: ~100 Upsilons in 2004 • U has never been measured in heavy ions before • Next step, implementation and testing online. (Hank, Falk, Tonko, Chris)

  18. Effect of Cos q Cut L2 cut on cos q < -0.2 is still quite safe for U. Topology trigger, limit by p/3, Limits J/Y p^ to ~ 5 GeV/c.

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