Diapositive 1

1
EMScale studies with events
Smaïn Kermiche Aurélien Mendès
CPPM IN2P3/CNRS Université de la méditerranée
Aix-Marseille II

• Method description
• MC and data samples
• Calibrations constants crate, phi and eta
  based
• The new geometrical corrections effects on MC
• Z mass resolutions crate, phi, eta
• Time variation of Z mass resolution

2
Method description
? MC Determination of an analytical shape of
the ee- invariant mass
Fitted as a convolution of a Breit-Wigner (fixed
Gz) and a Gaussian
? Data Determination of calibration constants
The calorimeter is divided in zones (limited by
statistics !). For each event i, with one
electron in zone k and the other electron in zone
l the invariant mass is given by
The calibration constants (e) are obtained by
adjusting this invariant mass with the analytical
function obtained with MC (maximization of a
likelihood)
3
MC sample and fit
PYTHIA MC Drell-Yan/Z-gtee- reprocessed with
d0correct v00-00-06 (TMBTree Files provided by NP
group )
New geometrical corrections included (01/28/2004)
4
Data sample and fit
2EMhighpt CS skim reprocessed with
d0correct_v00-00-06
Without any corrections
The calibration constants are obtained after
applying energy corrections for geometry effects
for electrons.
5
Crate based constants
ltNem-objgt/Zone EC north 450 CC
2017 EC south 565
5
-5
6
Eta based constants
2 zones in EC north (1,2) 4 zones for the CC
(3,4,5,6) 2 zones in EC south (7,8)
Zone 1 -2.5 lt h lt -2.0 Zone 2 -2.0 lt h
lt -1.5 Zone 3 -1.2 lt h lt -0.6 Zone 4
-0.6 lt h lt 0.0 Zone 5 0.0 lt h lt 0.6
Zone 6 0.6 lt h lt 1.2 Zone 7 1.5 lt h
lt 2.0 Zone 8 2.0 lt h lt 2.5
5
Nem-obj/Zone 509 1196 1449 2354 2504 1775 1465 656
-5
7
Phi based constants
Each of EC north, CC and EC south is divided in 8
phi zones
ltNem-objgt/Zone EC north 213 CC
1010 EC south 265
6
-6
8
MC ee- invariant mass versus h distribution
Before any correction
90 GeV
86.5 GeV
92.5 GeV
After geometrical corrections
90 GeV
9
data ee- invariant mass versus h distribution
after geometrical corrections
94 GeV
88 GeV
93 GeV
after Crate based corrections
89 GeV
10
Z resolution Crate, eta and Phi
Crate based corrections
Without any corrections
Eta based corrections
Phi based corrections
11
Z resolution with time (Run number)
Taking the crate based calibration constants, and
trying to see the variation of the Z partial
width (s) over time (run number)