DATA ANALYSIS FROM THE CERN TEST EXPERIMENT ABOUT THE HADES ELECTROMAGNETIC CALORIMETER By : Tazio Torrieri Supervisor : Vladimir Wagner
Jan 01, 2016
DATA ANALYSIS FROM THE CERN TEST EXPERIMENT ABOUT THE HADES ELECTROMAGNETIC CALORIMETER
By : Tazio Torrieri
Supervisor : Vladimir Wagner
PLAN
HADES experiment
The HADES electromagnetic calorimeter
The CERN test experiment
Data analysis and results
HADESHigh Acceptance Di-Electron Spectrometer
HADES
Study of nuclear matter properties at high density : Modification of hadron properties
HADES
Detection of electron-positron pair Extract the invariant mass of light vector mesons (ω, ρ, Φ)
HADES ELECTROMAGNETIC CALORIMETER
HADES ELECTROMAGNETIC CALORIMETER
Aim : Improvement of the signal from light vector mesons by removing the background.
Two main sources of background :
π0 → γ + e− + e+ η → γ + e− + e+ Dalitz decay≈ 1.2
%Charged pions
HADES ELECTROMAGNETIC CALORIMETER
Detection of gamma pair : π0 → γ + γ η → γ + γ
Better π− / e− supression for large momenta
HADES ELECTROMAGNETIC CALORIMETER
Replace the HADES pre-shower detector Placed at 2.40 m from the target 8m² required Angle covering : 18° < θ < 45°
≈ 840 lead glass modules from OPAL experiment
Module dimensions : 42 x 9.2 x 9.2 cm
CERN TEST EXPERIMENT
CERN TEST EXPERIMENT
DATA ANALYSIS AND RESULTS
Distribution of the energy deposited in the first detector
Electron peakfitting for the first detector
Energy calibration
Energy resolution
Expected resolution :5% / √E (GeV)
Gaussian + Exponential fitting
Gaussian + Parabole fitting
Distribution of the energy deposited in the first detectorafter energy calibration
200 400 600 800 10001200140016001800200022000.700
0.750
0.800
0.850
0.900
0.950
1.000
1.050
e− / π− separation
Series1Series5Series9
Energy (MeV)
π−
se
p /
all
π−
QUESTIONS ?