13/12/2007

In-situ calibration with Zee In-situ calibration with Zee eventsevents

Nikola MakovecGroup meeting

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OutlinOutlinee CSC Note EG-6, section Intercalibration

Motivation Data sample and event selection Description of the method

The fitting method Reference distribution

Method testing Results with misaligned and distorted geometry Conclusion

8 pages

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MotivatioMotivationnIn situ calibration of the EM calorimeter with

Zee events:

Intercalibration Non-uniformities

Temperature Purity Extra-material in front of the calorimeter

Local constant term ~0.5% (=0.20.4) Goal : 0.7% (TDR) Intercalibrate these regions to a level of 0.4%

Absolute energy scale Physics atlas program : ~0.1% W mass measurement : ~0.02%

LRL CCC

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Data sample and event Data sample and event selectionselection Data sample :

Trig1_misal1_csc11_V1.005144.PythiaZee.recon.NTUP.v12000601 Studies at the generator level

Trig1_misal1_csc11_V1.005144.PythiaZee.recon.NTUP.v13003002 Used after simulation and reconstruction

Event selection at least electrons The 2 leading should satisfy

pT>20GeV ||<2.4 IsEM(Medium)=true

80<Mee<100

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Description of the method (1)Description of the method (1)

Notation:

The fitting method: 2 step : Measurement

Minimising the following log-likelihood :

generalized least squared method is applied leading to an analytical solution.

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Description of the method (2)Description of the method (2)

The reference distribution

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Method testing (1)Method testing (1)

Done at the generator level Injected bias drawn from a Gaussian(,) Gaussian(0,2%)

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Method testing (2)Method testing (2)

Gaussian(,2%)

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Method testing (3)Method testing (3)

Expected constant term as a function of the luminosity

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Results with misaligned and distorted geometry (1)Results with misaligned and distorted geometry (1)

Gaussian(0,0%)

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Results with misaligned and distorted geometry (2)Results with misaligned and distorted geometry (2)

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Results with misaligned and distorted geometry (3)Results with misaligned and distorted geometry (3)

Gaussian(0,2%)

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Results with misaligned and distorted geometry (4)Results with misaligned and distorted geometry (4)

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ConclusioConclusionn With~200pb-1:

Constant term ~ 0.7% Absolute scale known with a precision of few

percent

Care of extrapolation to other energy spectrum (linearity?)

Amount of material in front of the detector : E/p Conversion Energy flow

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To do listTo do list

Corrections de la note : Fond? Forme Style et orthographe

Si vous avez un peu de temps: /exp/atlas/makovec/Notes/CSC-EG-6.pdf

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Pot pour mon retour au LAL :Vendredi 21 décembre à

11h30 Salle 129