Etude et impact du bruit de fond corrélé pour la mesure de l'angle ...

5.6 Estimation of correlated background for ✓ 13 measurement 155
by the grey histogram. The solid red line represents the linear model adopted
for the correlated background shape, while the dashed red line represents
the shape normalisation uncertainty.
tel-00821629, version 1 - 11 May 2013
Entries/(0.25 MeV)
3
10
10 2
10
1
0 5 10 15 20 25 30
Energy (MeV)
Figure 5.33: The final correlated background shape obtained upon OVV.
The signal selection performed in [0.7, 30] MeV is shown by the white histogram
and compared to the tagged correlated background shown by the
grey histogram. The solid red line represents the linear model adopted for
the correlated background shape, while the dashed red line represents the
shape normalisation uncertainty.
Since the OVV introduces a small change in the shape obtained without
OVV, a spectral shape uncertainty is introduced to account for such variation.
The spectral shape uncertainty is shown by the blue solid area in
Fig. 5.34 in [0.7, 12] MeV.
Spectral shape and its uncertainty parameters are summarised in Tab. 5.19.
The spectral shape parameters have been rescaled to the 0.25 MeV binning
used in the final fit. The uncertainties are propagated to the final fit in a
mixed approach. The normalisation uncertainty is accounted with a pull
parameter added to the
2 function of Eq. 4.5, in order to vary the spectrum
normalisation as a part of the fit. The shape uncertainty, which do
not a↵ect the spectra normalisation, is taken into account by a covariance
matrix.