Collaboration Meeting,August 12, 2003

Manuel Calderón de la Barca Sánchez

Heavy Flavor Working Group

L0 & L2 Trigger:

Status in our hunt for J/

L0 & L2 Trigger:

Status in our hunt for J/

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J/ Simulations for Trigger

DatasetPythia J/ mixed into AuAu Hijing~40K eventsMixing takes into account some acceptance

filteringHave sample of Hijing unmixed and mixed

(see next talk) Studies:

Energy at L2: bias, resolutionMass at L2: cluster size dependence, centrality

dependencePreliminary numbers on Efficiency

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How well do we get the e Energy in L2?

1 < E < 5 GeVPeripheral, 100-80%Single Tower Cluster

1 < E < 5 GeVPeripheral, 100-80%3-Tower Cluster

Tower energy obtained from reconstructed towers (after slowsimulator). Electron energy from original MC track.

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Tower Energy at L2: Energy Bias

Here, Tower energy obtained from MC Towers in GEANT.Electron energy from original MC track.

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Using the reconstructed Energy

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Not too much difference? Check the MC Energy of the tower, the reco

energy (seen at L2) and the MC energy of the electron.

MC ene. L2 ene. Ene. electron

e+ 0.9 1.5 1.37

e- 2.46 2.12 2.6

e+ 1.36 1.42 1.44

e- 2.04 ? 2.06

e+ 0.749 ? 1.72

e- 1.95 1.99 2.24

e+ 2.05 ? 2.34

e- 3.36 ? 3.76

L2 can be largerThan original energy

More worrysome,Calorimeter reco misses two high towers in the same event!

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Bias at E=M/2

MC Energy Rec Energy

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Slope of Energy Bias

MC Energy Rec Energy

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Energy Resolution

Not the best statistics here! Can improve by looking at the files, reach to ~8 GeV. (And if the disks at RCF don’t die!)

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Energy Resolution, with reco energy

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J/ Mass at L2, Mean

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J/ Mass at L2, Width

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Isolation Cuts, 1-Tower Cluster

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Isolation Cuts, 2-Tower Cluster

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Isolation Cuts, 3-Tower Cluster

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Isolation Cuts, 4-Tower Cluster

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Isolation Cuts, 5-Tower Cluster

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Isolation Cuts, 6-Tower Cluster

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Some numbers on efficiency

100-80% 80-60% 60-40% 40-20% 20-0%

Events 7970 7436 7673 7676 7751

Accepted J/

527 527 513 526 505

L0 Trigger

190 873 4068 7447 7748

L0 Trig. & Accepted

100 165 365 514 505

L0 & L2 Trigger

113 528 3527 7385 7748

L0 & L2 & Acc

71 139 334 511 505

L0 Eff. 0.19 0.31 0.71 0.98 1

L2 Eff. 0.71 0.84 0.91 0.99 1

L0 Bg. Rej.

82.7 9.75 1.9 1.03 1.0004

L2 Bg. Rej.

21.14 1.8 1.15 1.01 1

L0 Reco. Energy> 1.2, L2 Mass > 2.4, 3-Tower Cluster

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Status & To do Finalize numbers on rejection factors Multiplicity, how high does it make sense to run

the trigger?Currently estimate that 100-50%

Resolution is still good Efficiency is high, and background rejection is

probably manageable Explore the efficiency using isolation cuts Combine the information and figure out how

many J/ per triggered event… Does it make sense to run the trigger without

TPC? Resolution is worse… but might boost statistics by

factors of 10-50!!

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Goal for next run… Catch ‘em and bottle ‘em!

Yield w/o trigger:50 J/ per1M min-bias events

200 J/ per1M 10% central events