Offline zero suppression

1
Offline zero suppression
Stephanie Beauceron LPNHE Paris Collaboration
Meeting 10/09/2002

• Aim
• Look at the effect from the coarse hadronic on
  Missing ET
• Missing ET from cells with negative energy
• Runs studied
• 163392 2.5? run online from 6th of September
• 162594 1.5? run online from 25th of August and
  2.5? offline

2
Met and Set at 1.5? and at 2.5? on zerominimum
bias events
Met
Set
162594 1.5? online 162594 2.5? offline 163392
2.5? online
Met is 3 times more importantin run 1.5?. In run
1.5?, there is 5 times more energy than in run
2.5?.
Mex
Mey
The run at 2.5? offline has values just on the
middle of the 2 others.
3
Met and Set with/without CH on 2.5? run
Zero and Minimum Bias events
Diminution of 1.2 GeV in Met and 10 GeV in Set
From CH Without CH With CH
? In the coarse we add 4 GeV ? The SET 43.4
GeV?94.6 GeV
QCD events
Diminution of 1.2 GeV in Met and 14 GeV in Set
From CH Without CH With CH
4
Met and Set with/without CH on 1.5? run
Zero and Minimum Bias events
Diminution of 3.2 GeV in Met and 68 GeV in Set
From CH Without CH With CH
? In the coarse we add 4 GeV ? The SET 235
GeV? 345 GeV
QCD events
Diminution of 2.4 GeV in Met and 72 GeV in Set
From CH Without CH With CH
5
Conclusion on Coarse Hadronic

• For zero and minimum bias events
• at 1.5? the CH energy represents 29 of total
  scalar ET
• at 2.5? the CH energy represents 22 of total
  scalar ET
• For QCD events
• at 1.5? the CH energy represents 21 of total
  scalar ET
• at 2.5? the CH energy represents 15 of total
  scalar ET
• Just adding more noise   

4 GeV
Coarse Hadronic
With Coarse Hadronic
WithoutCoarse Hadronic
MET
SET
6
Energy cells distribution in zero and minimum
bias events
162594 1.5? online Mean 0.019 RMS 0.241 163392
2.5? online Mean 0.065 RMS 0.297 162594 2.5?
offline Mean 0.042 RMS 0.234
The mean value is positive.
7
Met resolutions for QCD events
162594 1.5? online 162594 2.5? offline 163392
2.5? online
? Cells with positive energy
? Cells with negative energy
?Similar variation between Met from
negative/positive cells
8
Met resolutions for zerominimum events
162594 1.5? online 162594 2.5? offline
? Cells with positive energy
All Cells ?
?Same noise variation between negative/positive
energy cells
9
Conclusion

• Since some runs are not good ? We have just one
  run at 1.5? and one at 2.5? close to each other
  More runs will be studied.
• On Coarse Hadronic
• There is some amount of energy in CH but much
  smaller than the noise especially at 1.5?.
• ? We should remove it.
• From negative energy cells
• The noise from positive energy cells and the one
  from negative energy cells are varying in the
  same way.
• Others studies are in process.