2. J/Y Simulations for Trigger
Dataset
Pythia J/y mixed into AuAu Hijing
~40K events
Mixing takes into account some acceptance filtering
Have sample of Hijing unmixed and U mixed (see next talk)
Studies:
Energy at L2: bias, resolution
Mass at L2: cluster size dependence, centrality dependence
Preliminary numbers on Efficiency

3. How well do we get the e Energy in L2?
1 < E < 5 GeV
Peripheral, %
Single Tower Cluster
1 < E < 5 GeV
Peripheral, %
3-Tower Cluster
Tower energy obtained from reconstructed towers (after slow
simulator). Electron energy from original MC track.

4. Tower Energy at L2: Energy Bias
Here, Tower energy obtained from MC Towers in GEANT.
Electron energy from original MC track.

5. Using the reconstructed Energy

6. Not too much difference?
Check the MC Energy of the tower, the reco energy (seen at L2) and the MC energy of the electron.
L2 can be larger
Than original energy
MC ene.
L2 ene.
Ene. electron e+
0.9
1.5
1.37 e-
2.46
2.12
2.6
1.36
1.42
1.44
2.04 ?
2.06
0.749
1.72
1.95
1.99
2.24
2.05
2.34
3.36
3.76
More worrysome,
Calorimeter reco misses two high towers in the same event!

7. Bias at E=M/2
MC Energy
Rec Energy

8. Slope of Energy Bias
MC Energy
Rec Energy

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

10. Energy Resolution, with reco energy

11. J/y Mass at L2, Mean

12. J/y Mass at L2, Width

13. Isolation Cuts, 1-Tower Cluster

14. Isolation Cuts, 2-Tower Cluster

15. Isolation Cuts, 3-Tower Cluster

16. Isolation Cuts, 4-Tower Cluster

17. Isolation Cuts, 5-Tower Cluster

18. Isolation Cuts, 6-Tower Cluster

19. Some numbers on efficiency
L0 Reco. Energy> 1.2, L2 Mass > 2.4, 3-Tower Cluster
100-80%
80-60%
60-40%
40-20%
20-0%
Events
7970
7436
7673
7676
7751
Accepted J/y
527
513
526
505
L0 Trigger
190
873
4068
7447
7748
L0 Trig. & Accepted
100
165
365
514
L0 & L2 Trigger
113
528
3527
7385
L0 & L2 & Acc 71
139
334
511
L0 Eff.
0.19
0.31
0.71
0.98 1
L2 Eff.
0.84
0.91
0.99
L0 Bg. Rej.
82.7
9.75
1.9
1.03
1.0004
L2 Bg. Rej.
21.14
1.8
1.15
1.01

20. Status & To do Finalize numbers on rejection factors
Multiplicity, how high does it make sense to run the trigger?
Currently estimate that %
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/y 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!!

21. Goal for next run… Catch ‘em and bottle ‘em! Yield w/o trigger:
50 J/y per
1M min-bias events
200 J/y per
1M 10% central events