Analysis Meeting,November 9-11, 2003
Manuel Calderón de la Barca Sánchez
Heavy Flavor Working Group
Heavy Flavor in ‘04:
Prospects for J/.
Heavy Flavor in ‘04:
Prospects for J/.
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Status of Studies for 2004 Run
Full document on the web http://www.star.bnl.gov/protected/heavy/www/proposals/oni
um.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
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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/: Requiring Eelectron>1.2 reduces the signal
Minbias Top 5% Top 10% Top 20%
J/ 1.35 x 10-4 6.21 x 10-4 5.54 x 10-4 4.46 x 10-4
’ 4.96 x 10-6 2.28 x 10-5 2.03 x 10-5 1.64 x 10-5
1.18 x 10-7 5.43 x 10-7 4.84 x 10-7 3.89 x 10-7
’+’’ 4.31 x 10-8 1.98 x 10-7 1.77 x 10-7 1.42 x 10-7
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Production Rates IIJ/ Yield:24 J/ e+e-, p>1.2 GeV per 1M min-bias events
98 J/ e+e-, p>1.2 GeV per 1M 10% central events
Yield:0.046 e+e-, p>3 GeV per 1M min-bias events
0.19 e+e-, p>3 GeV per 1M 10% central events(Triggered event ~ central)
Include:- fAB (hard fraction)- 1 unit 4- Acceptance (3/4 Barrel)- momentum cut
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Simulations for Au+Au @ 200 GeV Background
Hijing Minbias Signal
Pythia; settings tuned for J/, modifications for
Processed Background and signal in GSTAR Mixed 1 quarkonium event with 1 Hijing
eventDone at ZEBRA bank level (M. Potekhin)
Run algorithmsHijing dataset : Background Rejection PowerHijing + quarkonium : Trigger Efficiency
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EMC Topology Trigger Divide into 6
sections Find a tower above
a threshold Look in the 3
opposite sections in
If another tower above threshold, trigger.
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J/ Trigger: L0 Efficiency and Rejection
Eff
icie
ncy
Rej
ectio
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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
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J/ 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.
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Trigger: L0 Efficiency and Rejection
Compare 2 approaches at L0, the topology trigger and the single High-Tower trigger.
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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.
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J/: L0 & L2 Efficiency and Rejection
Most of the work is done by the topology trigger.Again, high rejection only for peripheral events.
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J/: L0 & L2 Efficiency and Rejection
For central collisions, every event fires
Trigger works for low multiplicity, where yield is small.Not much to gain…
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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%.
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Trigger Performance
R Cuts
L0 L2
High-Tower ADC
ClusterEnergy
Cos Mass
Efficiency 0.95 300 10 4.5 0 7
Balanced 0.90 833 10 5.0 -0.2 6
Rejection 0.85 2174 10 5.0 0 8
Trigger works beautifully. Large rejection power and goodEfficiency.The problem is that there is not much signal!Need Luminosity!!
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Putting it all together: J/ 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.
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Rates
Trigger enhances yield by more than a factor of 10.Trigger works!
Even at the highest L,L0 Rate is ~100 HzL2 Rate is ~ 3 HzLow rate.
L2 Rate can be reduced by ~3 keeping efficiency highRoom to move.
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Heavy Quarks in Run IV: Charm J/ 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/ Analysis will rely on large minbias and central
data sets.50 x 106 minbas + 50 x 106 central
3 signal + 5 signal in central Based on very conservative estimates on
background rejection (significance ~ e/h)
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Heavy Quarks in Run IV: Beauty
Trigger looks promisingEfficiency 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
has never been measured in heavy ions before
Next step, implementation and testing online. (Hank, Falk, Tonko, Chris)
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Effect of Cos Cut
Topology trigger, limit by /3,Limits J/ p to ~ 5 GeV/c.
L2 cut on cos < -0.2 is still quite safe for .